© Richard Barker

November 2001

The shoreline represents a natural boundary between sea and land; the last sight of home; the first sight of a distant land, perhaps of a new discovery. It was a major hazard for the seaman, despite the ancient practice of pilotage prior to celestial navigation.

The logic may however be partially inverted. For the ship, it was the first sight of its intended home: but for a ship of any significant size the limit of sea and land was also a most fundamental barrier to navigation. Ships are only built, and to some extent repaired, on dry land. That barrier presented great problems for shipbuilders and seamen alike, that had to be overcome before any navigation was possible. Cradle (berço, ber) is a good term for the structures created to tend the infant ship on that first short and perilous voyage.

Its significance for a conference on the Treaty of Tordesilhas and the limits of land and sea was obvious. That treaty was to divide the world; more precisely the oceans, as little was known of the lands in question. Without ever larger ships to master and exploit the oceans and new lands that division was meaningless¹.

This paper will explore some of the evidence for early methods of launching large ships about 1500, and in the subsequent period of exploitation of the new discoveries up to the early nineteenth century; and also for the even more difficult process of hauling large ships ashore for repair; all at the limit of sea and land, but also of technology. The records are sparse until about 1600, and even then difficult to interpret fully, even contradictory. Knowledge of many critical practical details has vanished, and has not yet emerged in archaeological contexts. It is however certain that the methods of launching large ships underwent a profound transition at the end of the seventeenth century, when cradles and slipways developed to allow the largest ships to slide freely to the water. Before that development, and in many places for long after, ships were laboriously dragged afloat in immense temporary structures, "worlds of timber", the cradles of the title. The process could take many days to complete. With skill and good luck momentum may have taken over in some launches, especially of smaller vessels, but that, as will be shown, was not the expectation in most recorded cases. Many of the sources used are necessarily much later material. This will be put in context to explore the general development of methods in Europe, and to illustrate the nature of the original problem. Significant differences emerge between northern and southern European methods. The methods of the industrial age such as patent slips and floating docks are essentially omitted here; and the use of dry-docks for shipbuilding in England from no later than the period of Tordesilhas is similarly only touched upon here².

The resources required to launch a large ship were vast: men, materials, and equipment probably more powerful than that required for any other contemporary application. They would vary in extent and detail with local conditions such as tides. The launching of Brunel's Great Eastern, at 12,000 tons launch weight stretched the technology of steam and iron as surely as any earlier large ships had done that of timber, rope and muscle. This ship was the great nau of its age, intended to steam non-stop to India and beyond. The launch was a national event, probably better recorded than any other launch. That launch was also protracted, begun in 1857 and completed in 1858; but the challenge faced by earlier shipbuilders was very similar. Indeed features of the cradle can be traced directly back to the cradles for India naus, and the records provide insight into much older problems. Only after the shipbuilders' triumph over brute forces at "the limit of land and sea" could navigation begin.

The paper is illustrated with drawings which should be regarded as simplified representations, not exact. Translations given are generally by this writer. Terminology is a problem, but as far as practicable later English terms are used for consistency (see also Fig.Hand-out). Brad Loewen and Éric Rieth in particular have kindly assisted this study with copies of some of the French and Spanish sources.
 
 

The North

Chronologically the present evidence starts in the North, and while the methods differ from those recorded from Iberia, they are probably more ancient, and provide points of interest. Two distinct sets of early records can be adduced for launching in northern Europe: late thirteenth century records for English galleys, and for the launch of a small vessel in Flanders in the fifteenth century; and seventeenth century Dutch texts. There is a comparable modern example too - listing, below.

Twenty galleys were ordered to be built around the coasts of England in 1295, and a number of basically similar summary accounts in Latin survive from their construction³. They seem to have averaged about 100 oars, but were still relatively small vessels. Typically the building site was set up specially, and perhaps surrounded with a fence for security. Purchases of scaffolding and alder spars for shores are recorded, and launching seems to have been carried out on rollers running on planks down a slipway dug for the purpose - a delf. At one site (Newcastle) eight labourers were employed for four days in wetting cables⁴. The published commentary suggests that this was to shorten the cable to start the vessel moving down the slipway, but if rollers⁵ were in use there is no obvious need for very large starting forces; wetting a cable will only move the hull a very short distance and cannot readily be repeated. The description is however reminiscent of later texts describing wetting the gammonings to help lift large vessels off their keel blocks prior to launching⁶.The hull weight has been estimated as not less than 50 tonnes. Considerable quantities of rope were bought, apparently for the operation of launching. Several similar fragmentary notices have survived for isolated launchings7.

The launch in Flanders in 1438-9 was of a pair of small carvels for the Duke of Burgundy, which were built (if not necessarily launched) by Portuguese shipwrights sent for the purpose. Their size is not stated but can be estimated from the work recorded as of 35-50 tons burthen: again, small vessels. The relevant items are⁸:

The greased planks onto which the hull was lowered are a possible link to the later methods of the Netherlands, and argue for some continuity between 1438-9 and the first available Dutch records, from the second half of the seventeenth century. For a vessel of this size, and bearing in mind the Dutch practices described below, the operation of lowering may well have consisted of first wedging and levering the hull over onto blocks under one bilge, to raise the keel off its building blocks, removing part of the keel blocks, and then reversing the tilt to lower the bilge blocks it had rested on, successively.

Dutch sources contribute further insights to the processes of building and launching¹⁰. Dutch methods became divided geographically into two traditions, with a boundary developing somewhere between Amsterdam and Rotterdam during the seventeenth century¹¹. Van Ijk described in 1691¹² (Fig.1a) the new procedures of the southern area centred on Rotterdam, in which the shipyard consisted of a floor of planks something over 3 metres wide and some 40 metres in length specifically to spread the load from the keel blocks. These were set up to a height of about one metre. This height was necessary because some of the frames were set up in advance of planking. The bottom planking had thus to be worked on from below. Witsen described the original method still centred on Amsterdam in 1671¹³, and although he has less to say about the structure of the slipway and stocks it is clear that the keel blocks were much lower - perhaps only 0.3 metres above the floor of the yard. This was because the bottom planking was built up before any framing, and was therefore completed while the hull remained much lighter for a given size of vessel. The whole assembly, which had the stiffness and strength of a shell at this early stage, was simply tilted to each side to provide better access to the underside of the planking. Witsen's keel blocks are restrained from movement during this process by posts driven against them. Apart from the fact that the northern Dutch method of building as a whole has obvious links to the methods of mediaeval northern Europe as seen in the remains of cogs, for example, the reasons for the different developments in this otherwise relatively small and homogeneous area are obscure. Historically there has been a much stronger boundary between Rotterdam and Flanders, than between Rotterdam and Amsterdam. Nonetheless it may be that Flanders' role as an entrepôt - for Portuguese trade for example - may have extended to shipbuilding methods in its closer neighbour (only certain aspects of southern European methods were transferred).

The final development of Dutch methods of launching for large ships, at least for the northern area, is recorded in engravings and models from the eighteenth century¹⁴. Chapman also records the details (for a relatively small vessel) for 1768¹⁵ (Fig.1b), where it contrasts sharply with the French and English methods. It is quite unlike the methods described elsewhere in this paper in many details. Firstly, there is no cradle. The bilge is supported directly on two inclined planks erected under the bilges: inclined both at the angle deemed necessary for the hull to slide, which might be steeper than the original line of keel blocks¹⁶, but also transversely to match the angle of the bilge, giving a dihedral effect. This would provide the primary means of securing the stability of the hull during launching, provided the sliding planks (supported on piles of transverse planking that formed the standing way) did not move under the loads applied, either vertically, or sideways under the inevitable wedging action. These ways have no need to extend inland beyond the point of maximum section of the hull. Typically this was forward of midships, and the Dutch continued to launch bow-first, so the launching ways were relatively short. The ways were built upon piles of planks set at close intervals, and they were heavily shored laterally to posts driven along the slipway. There were also means to reinforce the guidance of the hull, built around the keel: either a series of grooved blocks, or a channel formed of planks in place of the original keel blocks. If there had been any vertical load transferred back to these pieces, the hull would have tended to fall sideways: they can only have been intended to guide it in a straight line while its weight remained on the two standing ways. Interestingly these ways are markedly steeper beyond the end of the building area, but no indication is given of their extension beyond the water's edge. It is almost as though the whole ship is intended to pitch forward into deeper water as the bilge moves forward (indeed this appears to be happening in the frontispiece of Van Ijk's book, the bow of a small vessel plunging, and the stern rearing up from the ways), but at great risk that the stern would then ground heavily dynamically, as buoyancy lifted the bow (Fig.2). Witsen has a similar illustration, showing the point of rotation. It is difficult to see how it could work unless the bilge is firmly supported at least until the stern is clear of the end of the building slip, making the method suitable only for vessels with long flat floors. It also required deep water adjacent the slip; such a site would not serve for hauling ships ashore. Van Ijk himself remarked (the translation is by courtesy of Albert Hoving):

At about the same date as Van Yk, Rålamb in Sweden published his Skeps byggerij…. in 1691. The author had studied both English and Amsterdam shipbuilding, preferring some aspects of English methods, but in a well-known plate shows stages of construction in two Dutch methods, bow to water. The final stage has a ship ready for launch, with a very conspicuous dagger-shore from the hull planking (indeed Sutherland's drawing of 1711 is strangely reminiscent of this detail - see below). Judged solely on the lines in the plate as reproduced there appear to be longitudinal standing ways ending under the bilge, in the Dutch fashion, but real detail is not discernible. The text¹⁸ refers to bilgeways squared from old masts, and they thus seem to be sliding with the vessel, on transverse groundways alone: not the Dutch method. The hull is packed up off the bilgeways, and there is no support under the keel. The figure also shows single shores fore and aft (like the later English spurs) from the bilgeways to a wale, to prevent the ship falling over (in the apparent absence of poppets).

A model¹⁹ in the Royal Danish Naval Museum is of a large ship, Tre Lover, representing its launching in 1730. This appears from the photograph (p47) to be in the Dutch method, bow-first, with standing ways raised under the bilges, but no cradle. There are drivers placed at the stern, and heavy tackle between the water's edge and a cable suspended round the sternpost: clearly free-sliding was not to be relied on here.

Before turning to Mediterranean and Iberian methods, a few other primitive methods may be noted. One published text describes the preparations for the launch of a "galleon" of some 500 tons in Poland in 1571²⁰. The ship itself was built by Venetian shipwrights. It was launched with a cradle made from three specially purchased large tree-trunks (needing six horses to haul each one), and ten smaller "tree-trunks" which were only on loan - and were perhaps rollers, if they were not to be altered. This text contains two other intriguing references: to testing watertightness of the hull before launching by partly filling it with water; and for loading ballast in barrels - perhaps for convenience of handling, or for lack of suitable stone. It may also be noted that shipbuilders (like seamen) were itinerant, and must have taken their own local methods with them, but equally may have adopted the methods of others as they observed something different or better. In the case of Portugal, many aspects of shipbuilding can be traced to early employment of Genoese shipbuilders from the twelfth century²¹, and this must extend to methods of launching, as we shall indeed see below.

Three similar examples may be mentioned from other areas. One recent Greek method for small vessels was to place a pair of tree-trunks under the hull, one under each bilge, and large enough to extend below the level of the keel, and running on rollers. Another method of handling the great weight of the hull during operations such as lowering it, avoiding damage from levering on small areas, and reducing the risk of supports slipping, was to pack sand-bags under it, cut away the original supports, and then burst the sand-bags²². As described, this was to lower the hull sideways to rest on a standing way laid at one side of the keel, and reminiscent of the account of 1439 from Flanders. A method observed in Madras about 1850 used coils of rope packed with sand, which were slowly unwound to lower the hull²³. Such simple practical devices may have been widely used, unrecorded, within more complex operations on large ships - and most notably for the Flanders carvel which was explicitly lowered by otherwise unknown means.

Sometimes passing references testify to the use of brute force. Pyrard de Laval observes in 1610 "I have also seen an elephant draw ships and galleys ashore, or launch them afloat", and reports that for beaching in Cananor a century earlier (1501) "they put the side of the vessel foremost, and under the said ship they put three pieces of wood, and on the side next the sea I saw three elephants kneel down and with their heads push the ship on dry land". In the time of Akbar (1593) an unusually large ship was built that took 10 days to be launched by 1,000 men - capstans not being in use at that time; and while in 1501 it was customary to launch with an elephant on each side of a ship, this had been abandoned since the elephants sometimes caused the death of seamen²⁴.

One method noted by Ollivier in 1736 from France²⁵, though declining in use, was to actually launch the vessel "on its keel". This required the supporting grid to be built up to the keel, and a form of bilgeway which he terms coite (not unlike the coënte of later cradles' bilgeways), was actually fastened directly to the hull, so that the hull was supported in three places. This has some similarities with the Dutch method. The coite was only removed on first careening of the vessel. Ollivier clearly dislikes this method, which he states was prone to premature movement, and to overturning of the ship. It was also, he adds, damaging to the hull, for lack of adequate support, and much more difficult to restart the launch if movement stopped.

This method is what Bouguer describes in 1746²⁶, though with fewer reservations; and ostensibly only the vocabulary differs between Mediterranean and Atlantic France.

Something very similar was in use around St Malo in the early twentieth century, to launch Terre-neuviers of around 350 tonnes hull weight, which has been described in some detail, with the contemporary French terminology²⁷. The slipway here was extended on timber trusses into deep enough water.

There is even a record from the East coast of England from the first half of the twentieth century²⁸, which clearly indicates that early Northern methods survived for smaller vessels, in parallel with developments for larger ships. The account is for wooden fishing drifters of around 28 metres length, launched at a yard near Lowestoft, where the method was known as listing. A standing bilgeway was established under one bilge, consisting of long lengths of "hollows", baulks with the upper surface hollowed out. On this was placed a single long "round". The mating faces were smoothed and greased (with a mix of horse fat and Russian tallow, which was liable to seize in cold weather) as the sliding surface. The vessel was then jacked up on the other side, until it rested on the round, at its bilge, packed up as necessary. A similar arrangement was then constructed under the keel, in place of the stocks, and the hull lowered again. The hull was then winched to close to low water mark, shifting the hollows from the bow end as it passed, to extend the ways to the water. The ground surface steepened near the water, and a more conventional launching was arranged for the final descent on the next high tide.
 
 
 
 

Mediterranean methods

The most useful notices available from primitive Mediterranean methods for launching are Crescentio's in 1607, and a representation of the Venice Arsenal purportedly from 1517²⁹ showing galleys and larger vessels supported on piled blocks under the bilges - which if correctly drawn cannot be the original keel blocks for initial construction, though they may take the place of shores. The same methods had clearly also spread to Portugal, as revealed by the use of the Italian term vaso in Portugal no later than the first half of the fifteenth century, noted by Carbonell Pico³⁰, and presumably derived from the older Mediterranean galley tradition:

Crescentio had heard a garbled account of the tides of the Gulf of Camboia, which he describes as a great convenience for launching in comparison with the difficulties of the Mediterranean. He then describes the Italian techniques used for galleys and larger vessels, based on the use of articulated bilgeways, supported from the hull by ropes, and moved on rollers. While it is not a clear description (despite reference to hollow boxes, the vasi are drawn as simple planks on edge, for example), the elements for larger vessels are identifiable³² (Fig.3):

The Savona archives contain a record of the loan of eight beech vasi by a shipbuilder in 1575³³. These were some eight metres long, probably sufficient as a set for any local vessel, arranged as in Crescentio's drawing.

The drawing from Venice shows piles of baulks with alternate layers in different directions, just like those drawn by Lavanha for his keel-blocks, but placed at intervals under either bilge, apparently in addition to keel blocks as such. There is no indication of the relationship between these blocks and any vasi; but one vessel appears to have an isolated bow-cradle corresponding in part to later forms. Some of the hulls are ostensibly located broadside-on to the adjacent basin to which they would presumably be launched; and this may be related to a later account of launching galleys at Malta where the vessel was turned before launching (Teonge, below). It is perhaps unwise to place too much faith in this painting, as though the extant version is said to be a copy of an original of 1517, the hull forms at least have certainly been up-dated in the copy.

A painting of the Marseilles arsenal about 1670 by J-B de la Roze³⁴ shows a number of galleys being built behind walls that prevent their launch directly to the water. They must be moved more or less sideways a considerable distance before launching, though unfortunately the details of any arrangement for achieving this are not evident. This too may reflect what was described for Malta at the same period. These Mediterranean galley cradles were suitable only for longitudinal movement, and transverse movement on the narrow vasi must have required some form of standing way, not rollers.

The great timber cradle

The next major source chronologically (1616) is Fernandes³⁵ (Fig.4), who is of course describing the largest cradles of the whole era, for an India nau, an order of magnitude larger than Crescentio's vessels. He calls the cradle e(m)nvazadura (modernised as envasadura), clearly related to the original vasi. Fernandes was evidently a master shipwright, and approached his text from the point of view of a carpenter: the term great might well serve to describe a group of cradles. His drawing, although carefully to scale and containing two projections, is incomplete, and the vocabulary and syntax partly a mystery, but it is clear that he combines his vasos - in this case three lines of them under each bilge - with the piled baulks supported upon them to form cribs (casas - crib being a convenient rendering rather than an exact term). These are interlocked with multiple rows of dragas, which function as daggers, to hold the blocks carrying the hull's weight in their place. Pairs of daggers would in later methods be bolted either side of the poppets fore and aft, clamping them rigidly in line, and it may be supposed that Fernandes' dragas are their forerunners. The origin of the English term dagger for this context was apparently unknown in the early nineteenth century, and it may conceivably be a phonetic corruption from the dragas of these cradles.

In each case the problem is to support the weight of the hull upon the vasos, which form an articulated bilgeway, although the contact at the upper end of the support is steeply inclined at the ends of the hull, and will tend to be pushed sideways. Fernandes notes a difference in height of five palmos de goa (1.23 m) for his cribs across their width, matching the slope of the hull, which would be extremely difficult to fill with stable wedges: his text and drawing are incomplete and details are unclear. One major puzzle is that the layout of the vasos in plan follows the curve of the bilge: so do the cribs; and they appear to overhang the vasos by a considerable margin. By comparison with the later straight bilgeways and poppets and stoppings-up set upon them, this must have made it very difficult to fit the dragas. It does allow the height of the cribs to be minimised while providing maximum lateral and structural support at the bilge. The spread of the bilgeways appears over time to have become progressively less as a proportion of the ship's breadth, which helps to reduce the height of the cribs, stoppings-up and poppets, and the slope of the hull where they meet; but this also changed the nature of the support to the hull, and there may have been a relationship with developing systems of framing, for example, to permit it to happen. Such factors are far more significant in large vessels, but there is as yet no documentary or archaeological evidence to explore this further.

The tendency for the vasos and everything above them to separate is controlled by a heavy cable stretched across under the hull at every joint in the vasos. (The Great Eastern had the luxury of long North American timbers beneath the hull and of iron bars, but serving the same function). All the longitudinal strains of dragging the weight of the hull are carried through the vasos by the heavy pins, one palmo square linking all the vasos at every overlap. It is possible that this articulation is simply for ease of assembly of necessarily short components, but also that it was necessary to compensate for imperfect groundways. Interestingly, the vasos at the head of the cradle are turned up quite markedly, as though to prevent their digging into the ground: did the groundways not extend far enough, then ? That is certainly the implication of their stated length. It seems from this aspect that the hull was built with the bow towards the water, though it is not explicit (not least plan and elevation differ).

Items that are unclear are how the heads of the cribs are restrained, and how the complex of drag ropes are attached to the hull, and to the machinery - anchors and capstans - necessary to haul the hull and cradle. It is virtually certain that they are comparable to those described throughout the next two centuries in other sources.

Gaztañeta's manuscript of about 1688³⁶ (Fig.5) contains a similarly confused and incomplete account for a relatively large ship launched at Colindres in Cantabria. He too was a master shipwright. While the vocabulary is equally resistant to formal translation, it is clear that this method reflects an advance during the intervening 70 years. The cribs of Fernandes' cradle are now substantially replaced towards the end of the hull by individual inclined shores, probably in several rows across the width of the bilge, and all held in place by runs of daggers, bound across the shores by lashings at each intersection. (The upper dagger is drawn as single and is behind the poppets, unlike the later dagger plank. This may relate to the fact that in these earlier methods the poppets were actually restrained by the gammonings below the keel; though in this case they are not actually drawn). The bilge is supported through the central section of the hull on a solid mass of chocks and wedges, which also raised the hull clear of the keel blocks in the final preparations for launching. (What would later be called stoppings-up, longitudinal timbers directly under the bilge on which the chocks and wedges act, are apparently still absent - certainly from the drawing). The bilgeways (bassos, retaining the name though apparently not the form of the articulated cradles) are drawn as single timbers, almost as a convention. In practice these and all later bilgeways for large vessels would be made up from numerous lengths of very heavy timbers, all carefully jointed, and made smooth on the underside to ensure that they ran easily over the groundways. In this case the bilgeways seem to be joined by heavy timbers beneath the keel; though heavy ropes are in evidence in the text. There are already dog-shores acting between the groundways and the bilgeways to prevent the cradle moving prematurely; and some of the terminology indicates that driving shores, wedges and levers (palanculas) are all set up to start the cradle moving. These devices are an express statement that the first movement was vital: once moving the force needed was reduced (see below). The building slip appears to be relatively level, and then cambers away steeply to the water. Some considerable force would thus be necessary to move the cradle initially, and the effect of such uneven support to the hull cannot have been good, leading to severe hogging of the hull during launching (though there seems to be a reference to broad wedges required to support the stern "when the bow lowers"). This may be one reason why ships were almost immediately careened (or in England docked) after launching. There is no evidence here of launching ways extended beyond the immediate building area: see discussion under slipways.

An English account of 1636 refers to the cradles used to launch ships by the Portuguese, actually in Goa³⁷. The form of the cradle is not specified, but may be as that of Fernandes:

On the other hand, the term cradle was not unknown in England, even when launching from dry-dock. Butler has the following definition³⁸: "a framed piece of timber....brought up and raised all along the outside of a ship by the bilge when she is in dry-dock; and it serves to launch a ship with the more security out of this dry-dock. And in some parts these cradles are also used for the same cause, when any of their great ships are brought only to be trimmed; and they are trimmed in these cradles". This latter remark concerns the grounding of vessels for graving, re-caulking, etc.

Smith adds that it was a frame of timber much used in Turkey, Spain and Italy for more ease and safety in launching³⁹.

Albums

The next record to note represents a transition not so much of cradle construction (it is one or two decades earlier than Gaztañeta's), but of recording. Although unpublished at the time it is almost more readily classifiable as the first of the encyclopaedias than as a shipwright's record of carpentry. The Album de Colbert, anonymous and only datable to the period just before 1677, and reflecting the methods of Toulon, contains a drawing of a launching operation which places the emphasis on the tackle required to haul the ship to the water. It is a perspective view, and finely detailed by comparison with earlier records. It is the first to record the tackle (Fig.6), and the means of anchoring the hauling forces offshore (capstans on grounded "pontoons", drawn as cut-down hulks in this case). The heavy grillages of groundways are clearly drawn as forming a plane surface and to spread loads over the rough ground of the shipyard. The bilgeways are again drawn as single timbers, though this was a fiction. The cradle (Fig.7) has poppets fore and aft, but they are also continued along the bilge, interspaced between every second crib (though not yet as the later colombiers, as these spanned the bilgeway and stopping up). The cribs now show more clearly as alternate layers of baulks and wedges, built up to support longitudinal timbers called coutelas, literally cutlasses. One is under the bilge, effectively similar to the later stopping up; and the other is under the bottom, extending the whole length of the poppets fore and aft (and although it is not so drawn, almost certainly having the function of the English dagger-plank, nailed to the hull planking to act as a shole or sole-plate for the thrust of the poppets as the text implies). The function of the poppets is not just to shore up the hull, but to anchor the loops of the gammoning (three to each) which pass under the keel.

The main part of the hauling tackle is a set of very large multiple pulley blocks, fastened either to posts driven at the water's edge, or suspended from the transom on either side of the sternpost (it is a bow-first launch). A second set is similarly set up, but is lighter, and hauled directly by men, not a capstan: its function appears to be partly that of steering the cradle if it deviates, by pulling on one side, and slightly out of the line of launch. No guide ribbands have appeared yet. The text is not descriptive, but a catalogue referenced to numbered items on the drawing⁴⁰, headed:

The encyclopaedists: the carpentry cradle

The final group of sources to be described are eighteenth century, and may best be classified as a group as by encyclopaedists: they are the product of educated men, and were probably intended for publication, though not all reached that stage. These sources enable us to place the key date of transition in French methods between about 1677 and 1736. The cradles themselves have become less massive, more carpentry; but are not certain to slide freely.

Sutherland provides an early English example⁴¹. This is actually a limited account, but in the glossary to launch is "to lower or slide a ship off from the land into the water", and his "bulgeways" are simply "a piece of timber placed on each side of the bulge, to slide a ship". No other terms appear. The clearest feature is a massive dog-shore, which suggests a risk of premature sliding. Sutherland is concerned about the foundations of his slip, distinct from house foundations. If there is the slightest risk of settlement, he wants the ship to pass that point fast; but he prefers a gentler descent, to prevent her plunging too much and striking the ground. He makes a pretence of demonstrating that if the inclination of the slip is too great, the ship will accelerate disproportionately fast, but cannot quantify it. The keel is placed on splitting blocks, easily removed, above transverse groundways, which suggests that the hull is slid on the two bulgeways alone. The text mentions no sliding planks, but the plate, crudely drawn, could be interpreted as showing them, though the line could equally represent small ribbands to keep the bilgeways running in line. The bilgeways seem to be drawn out of scale, but with stoppings-up and poppets above them; they also have holes bored at both ends for ropes. The problem is compounded in that the plate shows a heavy longitudinal member between the bilgeways but above the transverse groundways, and running the whole length of the ways, and apparently below the keel, and not referred to in the text (Fig.16). Another curious feature is the very conspicuous dog-shore reminiscent of the 1691 drawing by Rålamb: not only is it very prominent, but it acts directly on the breadth of the hull: while there is a cradle interposed between the ship and ways in Sutherland's method, a short dog-shore between bilgeway and ground would be quite adequate.

Ollivier represents the full transition, with a treatise dated 1736⁴² that provides some of the best practical material of all, some of which has been noted above. He described bow- or stern-first launching as optional, and expects many but not all ships to slide freely, after initial resistance is overcome. He needs drag ropes to stop the ship drifting too far, for example. He does however say that vessels had not always been launched in such a simple manner with sliding cradles. The old method of capstans and tackle (caliornes) had been in use only a few years before, and was indeed still used by some. When ships had started to slide with this old method, the capstans could not keep up; in fact there were all sorts of hazards described for either method.

He has the following to say of the variant method noted above, where coites are secured to the bilges in lieu of a cradle - launching "on the keel":

Bouguer, in his Traité du navire of 1746, gives a description of what is clearly the same process as Ollivier's launching on the keel. He gives vocabulary, noting the differences between the Mediterranean and Atlantic areas of France, though perhaps not reliably, as will be discussed below. That is, he is apparently describing methods that we might expect to find in Toulon, in connection with the Royal Louis. He also has a longer passage describing the damage that arose on launching, and the hogging that followed as the vessel went afloat. While his information is interesting, it is also superficial.

The frontispiece of Duhamel du Monceau's Élémens de l'architecture navale of 1758, shows a ship arranged for stern-first launching, but the text does not describe launching.

Chapman in 1768⁴⁴ reproduced a formal drawing of launching arrangements ostensibly for Toulon in 1692 (Fig.8), with some descriptive text. The caption reads: "No.1 shows the arrangements for the launching of the 112-gun ship of the line Royal Louis, built in 1692 in Toulon with a length from stem to sternpost of 193 feet, a breadth of 52.5 feet, and a draught of 28.33 feet (Swedish feet). The figure shows how far construction had advanced by the time when she was launched. This method is still used by the royal yards".

It has to be noted that representations of the several Royal Louis have caused immense confusion in the past, summarised by Anderson⁴⁵. In essence, there is little doubt that Chapman's drawing is intended to represent the 1692 ship, and that he probably copied the original plans in Toulon, which he visited during his travels in the 1755-6⁴⁶. His plans agree broadly with the copy preserved in the Danish Archives⁴⁷, a slightly smaller ship than the vessel commenced at Brest in 1757 in the newly-completed dry-dock there.

However, the launch arrangements, while no great surprise for the 1750's, are anomalous for 1692. This is a full engineering arrangement drawing, albeit to a small scale; the contemporary original source has not been located, except that it has great similarity to Bigot de Morogues' work - see below. It differs from that of the Album de Colbert: the cribs have been replaced with stoppings-up in their final form, and there is far more precise detail. The method is still similar, though: a series of rope gammonings under the keel are used in conjunction with wedges within the stoppings-up to lift the hull clear of the keel blocks just prior to launch.

Details typical of Ollivier in 1736, Bouguer in 1746, and even the Album of Ozanne in 1765, are missing in Chapman's drawing. The heavy starting lever, the arc-boutant, for example, the drag ropes and tackle. This is however a stern-first launch on a sophisticated cradle, and there are ropes placed to restrain, rather than to drag the ship, unlike the details of the Album of Colbert of 1677. On balance, it seems probable that such a cradle was seen by Chapman in the 1750's, and is not contemporary with the 1692 ship. In this case, the difficulty in the early version of this paper (noted prior to the Berlin workshop), where it suggested anomalously early stern-first launching and free-sliding, compared with all other French sources located, is removed.

Interestingly, the drawing of a launching arrangement given by Bigot de Morogues in his manuscript Traité ⁴⁸ which dates from close to 1750 and has a context of Brest (indeed the description refers to tidal ports), is for practical purposes the same method as illustrated by Chapman, though in this case for a 64-gun ship. Its content is probably post-1738, as prior to that date Morogues had been an artillery officer. The technical content and drawing style are indeed so similar that we may suppose that the method observed was identical, or even that direct copying took place, by Chapman at least. That may reinforce doubts about the Toulon element of Chapman's caption, too ? Morogues' drawing is provided with an extensive key for the components. The term for the lashings between the bilgeways is traversalles, and the cross beams above them are the traversins, for example; he also includes an arc-boutant de chasse acting on the stem, with its starting wedges, missing from Chapman's drawing.

There is a more elaborate description of the avant-cale, the extension of the ways to the water (but not beyond). The first layer are the longitudinal corps-morts, on which transverse grillages are placed, with shorter pieces between them in three lines to maintain their separation, the entremises and clefs, the whole being tree-nailed together, and the result is reminiscent of the grade in Fernandes. Under the ship itself the ways are raised by longitudinals called longrines, usually in several layers at the bows, on which grillages are placed, between the stocks and with only two lines of clefs. The coite or stopping up is supported on chocks (chantiers) and wedges (coins). The poppets (colombiers) have a lip (adent) at their feet, to locate them on the bilgeway, and notches for the rostures near their heads. There is no dagger plank in this arangement, but the heads of the colombiers are cut to the moulds of the hull. The rostures are specified as white-rope - untarred, as they are to be wetted to shrink them. There are no sliding planks, only a guide ribband on each side. One new feature is that the edges of the grillages are to be chamfered - abattre la vive arrête. In theory at least, the ship will slide freely as soon as the final shores and keys are removed.

A warp (grelin) is attached to the hull on each side, to bring the hull under control after launching. The rudder is omitted at launching, and the gudgeons are protected by packings (coussins de sape) on the sternpost from impact with a raft of old masts (drome, estacade), placed to brake the ship as a drogue.

Another brief text from this period appears in Diderot & D'Alembert's L'Encyclopédie, dated 1765⁴⁹, which appears to draw heavily on Saverien of 1758.

The most complete text for this drawing however is that of V** in the Encyclopédie Métodique Marine of 1783⁵⁰. The procedures are more fully set out, including for example the need to allow the ship to adjust slowly to the strains of transferring it from keel blocks to cradle; of wetting the gammoning to increase its tension; drag-ropes to halt the ship when it floated; buoying the cradle, etc. His bilgeways were to be about 0.55 metres square, separated by struts, and held together by additional gammoning between them.

The provisions of Chapman's drawing of the French method are also to be found in a Spanish engraving⁵¹ from a much later date. The 50-gun frigate Restauración was launched in 1825/6, and the details are broadly the same, still using three sets of ropes under the keel from the tallest poppets. The engraving overall is original, with a slip cut out of a steeper bank, and a dog-shore being pulled out with an ox-train, so there is no reason to doubt that the remaining details are contemporary, despite their archaic appearance.

Chapman is the first to refer to sliding planks between bilgeways of a cradle and standing ways, but only for the English method, published in 1768 (noting that elsewhere a sliding plank was an alternative to the cradle). Falconer's Marine Dictionary of 1769 has a text description under launch: "..the ship is supported by two strong platforms, laid with a gradual inclination to the water, on the opposite sides of her keel, to which they are parallel. Upon the surface of this declivity are placed two corresponding ranges of planks, which compose the base of a frame called the cradle…..daubed with soap and tallow". He further indicates that the ways were generally extended far enough for the ship to float at the end of them, and that while starting screws were still provided, ships usually slid as soon as the shores were removed. First rates were usually built in docks: the 100-gun Britannia was the largest ever launched from a slip in England.

However, Chapman's published launching text is probably based on his notes for the launch of a 50-gun English vessel in the early 1750's. It contains a number of points of interest (text modernised from that in D.G.Harris, F.H.Chapman, London 1989, p20, 204-12.):

Steel calls the launching cradle a "grand piece of mechanism and requires every consideration". One pertinent comment is that cradles of his generation were greatly simplified, with the benefit of experience. He is strictly referring to the omission of the spurs formerly used in English cradles (as drawn by Chapman for example), that were a dozen or so frame-shaped shores bolted to the bilgeways and to the hull, for additional security in preventing the hull falling sideways, but complicating the process of separating the hull and cradle. He might as well be summing up the two centuries of development from the "worlds of timber" to the simple, if still massive, carpentry cradle of about 1800.

One interesting feature that only Steel refers to is that the cradle was first assembled piecemeal, cutting each piece to fit, and then dismantled in order to grease the bilgeways and sliding ways just before launching. The grease was a mixture of tallow, oil and soft-soap. This probably gives a truer reflection of the time and effort required to construct these huge cradles, but also to the critical effect of the loss of grease squeezed out during the first slow movement of the cradle (The problem continues to this day. The mix of lubricants is carefully controlled, and they are placed as late as possible, to avoid material degradation, with consequent increased friction, and loss under pressure, especially at high temperatures⁵³. Tallow may be used as a hard coating on the timbers, covering the grain and minor irregularities, with a softer mineral lubricant between. The fact that ways caught fire is evidence that past practice was very imperfect⁵⁴). Ollivier refers only to tilting the bilgeways with jacks to grease them. Steel also gives more details of the bilgeways (using decayed spars in part in his example), and joints between the parts, all snaped to prevent their fouling the joints of the sliding planks, and with all nails in these sliding parts punched a whole inch below the surface of the timber - itself a good indication of the violent nature of the movement of the cradle.

In addition Steel gives some quantitative details, for the launch of a 74-gun ship. The bilgeways are 140 feet (42.7 m) in length, 30 inches deep and 28 inches broad (762x711 mm). The 23 poppets each side are to be of fir, 26 inches (660 mm) athwartships (though they are drawn nearer 14 inches (356 mm) square for the 40-gun frigate of Plate 9); dagger planks are to be 3 inch (76 mm) oak plank, nailed to the hull with large-headed nails, so that they could be prised off easily after launching, and the daggers are 40 feet (12.2 m) long fir timbers 12 x 9 inches (305x229 mm). The ribbands that acted as guides to the bilgeways were to be 8 inches (203 mm) square, and the inshore end that held the dog-shores was to be oak, coaked to the sliding planks. The dog-shore, supported by a block called the trigger, is capped with iron, and rests against a cleat bolted to the outside end of each bilgeway above the level of the guide ribbands. (When the two triggers are removed, the dog-shores drop, and the cleats are clear to slide above the top of the ribbands. To ensure that the triggers on each side are removed together, two blocks of pig-iron are released down channels at the same instant; a procedure still used today). The sliding planks are to be set on a plane sloping 1:96 to 1:48 steeper than the keel blocks (which will be on a plane or cambered slightly upwards). Even in this almost final development of the cradle, the two bilgeways are held together under the keel by "several turns of lashings" between ring-bolts, which are bolted through the bilgeways with fore-locks that can be withdrawn (working from the ship) after launching, so that the two parts separate. Similarly, the inshore keel blocks are left to last after the slices (wedges) are driven, and screws are used to drive the ship if it sticks on the ways, replacing the earlier palancas and arc-boutants.

One significant item can be gleaned from these sources. No French or Iberian source as late as 1783 is known to refer to the use of longitudinal sliding planks between the transverse groundways and the longitudinal bilgeways, while English methods recorded from 1768 do specify these features. (In a sense they are the central feature of older methods, and of the Dutch method, using no cradle). This may be a critical factor in reducing resistance to sliding, as it reduces the bearing pressure at every point of the bilgeway by a factor of about two, and removes all the arrisses of the groundways from its path (Fig.10). If the bilgeway was crushed locally by uneven loads, that would hinder its movement, no matter how perfect its original surface. It is also much less likely that the vital grease will be scraped off the bilgeway by the edge of each groundway that it crosses.

A second curious but possibly significant feature is the absence of references to extension of the sliding surfaces below low water in early sources, such as Fernandes, Gaztañeta, Colbert, Ozanne, whose drawings show no trace of extensions, surprisingly. This will be considered further under slipways, below.

The puzzle of Bouguer's Traité du Navire

We may now consider a lengthy text by P.Bouguer⁵⁵, dated 1746, and which is thus roughly contemporary with Ozanne or Ollivier, Morogues, or Chapman's visit to France. Bouguer has a reputation for the identification of the metacentre, and for mathematical naval architecture. The evidence of this passage, however, is that he was not really familiar with launching, or practicalities. He was based in Paris and Havre, so he ought to have been familiar with tidal Atlantic methods; he actually prefers the use of dry-docks. It is doubtful, taking his text at face value, that he understood the dynamics of launching, as he confuses the effects of launching on the keel with launching off fixed bilgeways. The text extends to a discussion of the stresses imposed on launching and first flotation of a vessel, but not, it has to be said, in any quantitative fashion.

The text describes a method that is actually closer to Dutch methods (and with some aspects of launching on the keel) than other examples of French methods, and is perhaps archaic for 1746. There are a number of key terms which he uses differently from all other writers - berceau itself, anguilles, colombiers, and which suggest a garbled account. The text will be given in full, with interpolations to comment on the major differences and problems.

Evidence for difficulties in launching, confirmation that large ships did not generally slide freely into the water until the eighteenth century, can be gleaned from a number of disparate sources, where such events evidently cause little surprise. Often, incidentally, these accounts also illustrate the point that foreigners are either writing the account of events, or are involved in the work: it is no wonder that there is a tendency for the methods of launching large ships in Europe to converge during the eighteenth century, reinforcing the gist of earlier instances noted, that must have been commonplace.

Henry Teonge (chaplain of Assistance, man-of-war) made the following entry in his diary for 22 February 1676, at Malta, which reveals an unusual amount about the ceremonies of launching ships; about launching - "turned her head.... thrust" - (which perhaps throws some light on the Venice arsenal picture of 1517); and even offers a memorable collective noun⁵⁶:

A passage of rather greater significance for Portuguese shipbuilding history is to be found in the diary of another English seamen, Barlow, who found himself with others of the crew of the ship Queen Cathrane (ie Catherine of Bragança) waiting for a cargo of sugar to be loaded in Rio in 1663. The usual routine for seamen was first established⁵⁸:

Launching still did not always go smoothly even in the Ribeira das Naus, much later than this. There is a record from 1711 of the launch of a large ship of about 70 guns, which took four days to drag into the water, breaking quantities of tackle and hawsers in the process. This was in charge of a French shipbuilder, Chabert, and at the same time English and Dutch were also building in the yard⁶⁰.

Does this contradict a different account cited for 1721⁶¹, or indicate the date of a change of method in the Ribeira ? The Gazeta de Lisboa for 21 November 1721 describes the launch of two 50-gun ships, which proceeded with "the greatest velocity", the Royal family being present, seated in a richly furnished Royal Box constructed for the occasion. The launch was followed by a customary celebration with sweets and drinks.

The same commentary indicates that ships were launched with great pomp, and that "no power gave impulse to the fall of the great machine and its cradle....". There are reasons to question the date at which this became viable in principle, but had launching become a scheduled event for Royalty to attend, and can the reported velocity be taken literally ? Taken at face value these two accounts alone would place the date of transition in Portugal between 1711 and 1721, though other conflicting evidence is noted below.

Duro⁶² refers to a small manuscript work in the Biblioteca Nacional in Madrid entitled Arte de botar al agua los navios, which he ascribes to the second half of the eighteenth century, but he does not transcribe any part of it.

A few interesting points appear in a dictionary published in French, translated from the Dutch, in 1736⁶³. It contains plates that are reversed and modified copies of van Ijk's, and so launching bow-first in the Dutch method. The points to note concern the risk of fire, the Portuguese method, and internal reinforcements:

There is surprisingly little evidence from English sources for methods of launching before the eighteenth century. One reason is likely to be that many large ships were built in and launched from dry-docks from no later than the very early sixteenth century⁶⁴. An example features in the portrait of Phineas Pett, which has the stern of the Prince Royal (launched from dock in 1610) in the background⁶⁵.

This was no panacea, but did have advantages, not least in that once the investment was made in adequate dry-docks ships could also be repaired in them very easily - if not overnight, whereas it would only be worth hauling a large ship ashore for quite major repairs. (This would become a significant factor in the efficiency of the Royal Navy from the eighteenth century⁶⁶). Early docks were much more limited as to depth, because they had to drain freely at low tide, and had primitive gate arrangements that slowed down operations. It was precisely the need to drain dry-docks that limited their spread.

Phineas Pett noted some key points from the early years of the seventeenth century. He notes an event in 1609-10⁶⁷:

The launch of the smaller ship from stocks suggests that the process of driving wedges to transfer the ship to her cradle was badly managed, and either keel-blocks were not properly removed or the loading was placed very unevenly on the cradle, causing it to stick.

Butler's definition of cradle, above, using it also for launching from dry-docks, notes the other great problem of launching from docks that are too shallow for convenience. As the water rises to float the ship, the shores holding her upright must be removed. There is a danger that the ship will fall sideways during the critical phase where she is still partly supported on her keel, and is still unstable in the water. The dilemma is that additional ballast to improve stability also increases the height of tide needed to float the ship. This problem afflicted ships in the twentieth century too, and not just those launched from dry-docks⁶⁸. A painting in Merseyside Maritime Museum illustrates the case of the Baboo, of 423 tons, which fell over in the Canning Graving Dock in 1841 as water was admitted.

Pett has another significant remark concerning the launch of a very small ship of his own at Gillingham in 1604 which: ".....by carelessness ran off before her time without any great hurt"⁶⁹. This emphasises two aspects: small ships generally are much less problematic to launch. This particular ship probably had bilgeways from single lengths of timber, without all the problems of jointing and uneven support of a much longer and larger ship. More significant is that it was possible in the right circumstances and with sufficient care to make the slipway so steep and perfectly flat that a ship would slide of her own accord. As techniques improved this would become the norm, but it is likely to have depended upon the use of bilgeways, rather than articulated vasos, and on having sliding planks between the bilgeways and the standing ways. The questions remaining, for lack of evidence, are whether Pett was lucky to be launching only a small ship; whether it was normal for a well-prepared launch in England to slide the ship freely at this period (this writer knows of no other comparable evidence before Sutherland in 1711); and if so how the cradles and ways differed from those of other places, which clearly expected to need to drag most ships most of the way to the water, even if momentum took over on occasion once a ship was moving at all.

Part of the answer to why some slipways could be steep enough to generate comments such as Pett's or Sutherland's lies in the strong tides at most major English sites, exceeding the launching draught of all but the largest ships of our period. Builders could build slipways out to the low water mark, and be sure of sufficient water to float their vessel. That is not the case in the Mediterranean, or many other areas. A steep slipway is less attractive if large ships have to be hauled out too.

Pepys observed one failure to dock a ship in 1662. The Royal James was left with her nose in the dock, shored up and waiting for the next tide⁷⁰.

One of the more curious references to methods of launching - curious not least because there is no suggestion that it was anything exceptional at the time, is for a yacht built by Deane as a Royal gift to the French King, launched at Portsmouth in 1674⁷¹:

One of the most intriguing accounts of launching in English actually comes from fiction, in the work of Defoe. It suggests that the problems of launching large ships was well appreciated on any shipowning waterfront of his time - around 1700, and London - and perfectly illustrates many of the problems reported in this paper. The life and adventures of Robinson Crusoe - by no means a childrens' story (more a parable of modern "management") - find him of course marooned on his island, and determined upon escape. The longboat was dismissed, the up-turned smaller ship's boat essayed:

We have noted that the heavy pulley blocks near the sternpost are all supported from above, with ropes to the stern gun-ports in for example Colbert. This may reveal a possible key reason for all these early ships to be launched bow-first. With a straight sternpost and a long slender run, the hull is structurally better fitted to support the massive forces at the sternpost than at the bow, which is heavily sloping in several directions (Fig.11). If they had tried to attach the hawsers on the stem it would have been much more difficult to stop them slipping down the stem towards the keel, and the hood-ends of the planking and their adjacent frames might have been disturbed by the loads. There are other reasons to do with the dynamics of what happened when the ship finally came afloat, and building with the decks more nearly horizontal. However it is possible that we will find that large ships came to be launched stern first only when the cradles and launching methods had progressed so far that the ships usually slid down the ways relatively freely. While they had to be dragged, bow-first was a better method. The change as we have seen occurred in France at least between about 1677 and 1736.

A comment on the practical shipbuilding problems associated with dragging large ships is contained in a letter from Corte Real to the King in 1623, on the merits of three and four-deck ships⁷². Reinforcement of the sternpost with a counter- or false-post is spoken of in the context of needing to drag these huge ships.

We may however note that if a ship was subsequently hauled ashore it was most practicable to do so bow-first, so that the keel remained more nearly parallel to the beach and ways, and reduced the stresses upon the hull, and the length of the slipway (Fig.12). If ropes had to be attached to the hull to carry very large drag forces, they could then be placed around the sternpost in the same way as for launching. However, the ship had then to be re-floated stern-first. Now this dilemma and the need to develop techniques to accommodate it may have led to a realisation that launching could actually be performed stern-first too. This has dynamic benefits during launching, as the stern has less buoyancy than the bow, and will not lift so violently, increasing the load on the ends of the keel, and straining both ship and slip. It also allows the decks to be laid more nearly level during construction on a typical large vessel, which is another minor benefit to the work.

It will be difficult to distinguish in a view of a shipyard whether it was a new ship being launched stern-first, or a ship grounded for repair bow-first, and this may account for references to Portuguese launching stern-first surprisingly early, in the sixteenth century⁷³, apparently based on iconographic evidence. One supporting item comes from Van Ijk, who as we have seen wrote in 1691 as a matter of surprise that the Portuguese then launched stern-first. Barlow appears to draw the same for 1663, though the issue is far from clear, and merits further investigation.

Bowrey's drawing implying side-launching about 1680 will be discussed below: that is the only early example discovered for this study that provides any detail, though there are several others cited. The method had great merits and would become very common by the nineteenth century, especially for shipbuilding sites on rivers (such as for the exceptionally long Great Eastern) and canals. (Indeed it is said that some American river steamers, with lengths to 110 metres and depths of only 2.5 were simply allowed to float off level ground in spates, for lack of structural strength for conventional launching.

Dynamics of launching

A ship on its cradle reaches a point on the slipway as it is moved towards the water, however slowly, where the buoyancy of the seaward end starts to lift the hull off the slipway, rotating it about the landward end of the bilgeways. As soon as this happens, the end of the bilgeway is the only point where support is transferred to the cradle and thence the hull. At the same time, most of the buoyancy is concentrated at the other end of the hull. The relatively even spread of loads on the hull and slipway has transformed into severe localised loads, and causes the hull to sag - there is little support from the cradle in this sense. The ship has still to be moved some distance down the slipway before it is properly afloat and free of the slipway and cradle.

Launching a ship stern first will generally assist, as the stern usually draws more water and has less buoyancy than the bow, and the ship will tend to be further down the slipway before it rotates. Correspondingly, this requires a longer slipway. The curve of the stem also makes it less likely to ground during the process of rotation.

The greater the weight and draught of the vessel on launching, the longer the slipway needed to be, and the further below the high water mark. It was therefore advantageous to launch ships part-built. The ship was lighter to handle, needed less depth of water to float it, less (or no) ballast to make it stable, and was less likely to be strained by its own weight as it started to float and rotate. This also freed the slipway earlier for the next vessel to be started.

There is a contrary case in the methods where the primary support is on the bilge amidships - the Dutch method, essentially, but to some extent also with launching on the keel, or listing. As described above, the ship reaches a point where its centre of gravity is beyond the end of the standing ways, and it will tend to tip down into the water. However, this is shortly followed by the end of the bilgeway leaving the slip too, and the buoyancy will be tipping the vessel the other way: there is a very real risk of the keel striking the ground as its last support on the standing ways disappears. Launching into too shallow water or at too steep an angle can equally cause the leading part of the vessel to strike the ground.

This is a very real risk even today: one recent military launch suffered a collapse at the fore poppet, and the stem crashed to the slipway - striking the ground as it was termed - with structural damage. It happened to at least one of the famous heavy American frigates, for which items appear in the Naval Expenditure for 1798⁷⁴:

Small vessels can be hauled ashore manually when necessary, even when there is no tide to assist, or if it is necessary to carry out more protracted repairs than can be achieved between successive tides. Ships the size of caravelas, or rather larger vessels if they are designed to be so treated, and are being grounded on smooth sand or mud, with no risk of settling on rocks, or falling over, may be grounded in tidal areas relatively easily.

Classical galleys, which are estimated to have weighed around 30 tonnes, similar to a small caravela dos descobrimentos, were so hauled ashore in the almost tideless Mediterranean⁷⁵. Theophrastus⁷⁶ indicates that the keels of triremes were made of oak, so that they could withstand the abrasion from being hauled ashore regularly. Merchant-men had keels of fir, and if they needed to be hauled out had an oak plank placed to protect them. There are places where geography and prevailing winds even led the ancients to transport their ships considerable distances overland, notably across the Isthmus of Corinth, but also at Ras Banas⁷⁷. Dragging vessels up quite steep slopes was also a commonplace on Chinese (and other) canals and on the overtooms of Amsterdam's dykes⁷⁸.

Some of the issues associated with grounding ships were considered in an earlier paper⁷⁹, and will not be repeated here, but the point is made almost perfectly by a passage from Zurara's Crónica de Guiné⁸⁰. Antão Gonçalves' caravela left the Rio de Ouro about 1441, and immediately it was "seen how his caravela needed to be repaired, he had it put ashore, where he made it clean and repaired what was necessary, waiting on his tide, as was done before the port of Lisbon, at which daring many were astonished".

Fonseca states that ships to be repaired in Lisbon were put aground in cavas along the shore⁸¹, though no other reference to this has been found. Presumably these cavas were similar to the various forms of early "dock", more or less permanent and either with or without gates, that occurred in England from the fourteenth century⁸². Trueba cites a Spanish text that indicates that it was quite normal to haul ships ashore and even to raise them onto stocks for repairs to the keel about 1535: "sean barados en tierra e puestos sobre picaderos de manera que descubran toda la quilla" ⁸³.

As India naus grew in size in later years, only the greatest tides would serve much purpose in simply grounding such ships before the port of Lisbon, and few places en route to India were any better provided - with the exception of some places in Guinea and between Maputo and Mombasa.

The dilemma was clearly a real one, as the polemic over careening of India naus at the end of the sixteenth century shows⁸⁴. What is still not clear is what the alternative processes for repair of large ships were in India or in Lisbon, for example, and exactly how they were managed.
 
 
 
 
 
 

Hauling ashore

This is not just the reverse of launching: there are a few additional difficulties to note.

Explicit sources for the process of hauling ships ashore are even scarcer than those for launching. Polemics about careening and the (alleged) damage that its (alleged) introduction was doing to naus of the Carreira da Índia about 1600 suggest that even very large ships were hauled out for repairs in places like Goa, which had negligible tide for the purpose of repair of large ships, and no dry-docks. One of the earliest accounts located is in fact from Madapollam on the east coast of India about 1680, in which Bowrey briefly describes the local methods employed to haul out a 1,000 ton ship (but see below). The text is as follows⁸⁸ (Fig.13):

The next account to consider is by Ollivier, for southern France, about 1736⁸⁹. His text is:

A series of descriptions of machines for hauling ships ashore are given by the Academie Royale des Sciences for 1702-3. One of these is for the method actually used at Brest, and most of the other ports of France, according to its author, Blanchart. The other two are alternatives proposed by Blanchart and du Mé⁹⁰. Du Mé's method includes the development of a masonry slipway to contain grooves (three in fact - there was to have been a "bilgeway" under the keel too, as later described by Ollivier, above) in which many rollers were mounted, to reduce the force needed to drag the vessels and cradle. He is describing a forerunner of the "Patent Slip", where the cradle was fitted with wheels, and ran on rails. The slope was to be 10 in 144, so that the vessel did not have to be moved too far (though this is in fact unusually flat). The force was still to be applied with a prodigious assembly of very heavy hawsers and thirteen massive pulley blocks, secured between eight large half-buried anchors for the standing parts of the tackle and powerful geared capstans for the falls. The untarred hawsers were of 9 and 15 pouce circumference (77.5 and 129 mm diameter). The sheaves of the blocks were to have two and a half pieds (812 mm) diameter, and in the sister-blocks, the smaller sheaves, "that is to say those that come towards the narrower end of the shell, diminished always six pouces, also of diameter; but they always have the same thickness, which ought to be three pouces two lignes (85.7 mm), the hawser that serves them having nine pouces circumference". There were four geared capstans in this arrangement. Blanchart's were each worked by 36 men. Du Mé continues:

One point to note in this section is that the use of ships' anchors to secure the standing parts of the tackles for hauling ashore (or for launching) would be a dramatic test of their quality. Failures would be conspicuous, and the broken parts easily recoverable for examination. Design and construction faults in anchors, so important for the security of ships at sea, would be much more readily discerned, and not least by those responsible for their manufacture, than if they failed at sea, perhaps with no witnesses. The same might be said of the ropes and pulleys. Interestingly, similar tackle was widely used in the erection of statues and obelisks, but without a record of conspicuous failures. Stone is of course even more brittle than a ship, and in rare cases just as heavy. Thus we have engravings of the erection of a large obelisk in Rome in 1590⁹¹; and Catherine of Russia had a monumental granite base reputedly weighing a thousand tons moved in 1782, using iron cannonballs as a form of ball bearing between hollowed "bilgeways" and successive lengths of "standing ways" ⁹². Fincham makes the same point about ships in general: the loads are far less predictable than for many other constructions and machines⁹³. There are examples of large blocks extant, as at the Museu Militar in Lisbon, where a set of four shoe blocks⁹⁴ standing 1.5 metres high, each with three, four or five sheaves of 340mm diameter, all heavily iron bound. These were actually used for the erection of a statue of approaching 40 tonnes in Lisbon in 1774-5; but are much smaller than those recorded for launching ships earlier in that century.

An unusually detailed record survives for a slipway arranged for hauling ashore at Trieste in the mid-nineteenth century, "Arrippamento di un naviglio" ⁹⁵. The ways are extended on a foundation of stone blocks, on a cambered surface, with the camber increasing towards the water. There are again no sliding planks over the transverse groundways. The cradle is composed of a pair of heavy bilgeways, with cribs of wedges and rope restraints much as the old launching cradles. Four beach capstans are in use.

A brief description of how the cradle (or sledge as it was termed) was to be fitted under a ship for hauling ashore arises from a new slipway in Palermo: the whole was sunk under the vessel, hauled up close, and then wedges drawn along guides on crosspieces by ropes from above to prop it⁹⁶. This source also states that a slope of 1:13.3 is necessary to slide timbers separated by tallow and grease, but that over a short period of repair (or rest) the initial resistance increases by 5% of weight. The allowance on the hydraulic presses for the slip was thus 20% of total weight to haul a ship up the slip.

It is clear that such devices still exist to be recorded. A cradle, itself quite recent, but of an archaic form, lies on a steep pebble beach in Madeira, associated with substantial fishing vessels. Here there is no trace of groundways, though smaller vessels at the same yard have the benefit of a marine railway. The cradle consists of one long central baulk under the keel and two shorter timbers for the bilge. Two pairs of cross beams and wedges to roughly match the hull form tie these together, and iron bars transmit the drag forces between them.

Slipways

It is unusual to find information about the construction of slipways, or even about the range of techniques that might have been used in their construction. Thus Fernandes provides us with some details of the grade in 1616, but limited to a length that is no more than that of the hull: it is not clear what happened in the gap between the building area and the point at or below the low water mark where a large ship could be floated free of a cradle. Ollivier refers to the avant-cale that was required for launching in that zone, but his detailed text on the subject, if ever written, is lost.

A number of techniques were certainly available in principle for constructing the slipway beyond the low water mark where necessary. In the Mediterranean, for example, it would be quite impossible to float quite small ships onto cradles without constructing slipways below water; and the only alternative would be to drag a vessel over the natural sea-bed.

Caisson construction is an ancient skill, with considerable remains reported and methods reconstructed especially from Caesarea, though this was actually for the construction of harbour moles. Huge timber boxes were constructed, floated into position, sunk and filled with concrete or stone and hydraulic mortar⁹⁷. They are described for harbour works by Vitruvius. Classical methods could equally place individual stone blocks of at least nine tonnes weight⁹⁸.

Cofferdams could be constructed by driving sheet-piling, in suitable ground, and then working inside in the dry to create a permanent structure within them. Ramelli provides details of elaborate cofferdams and the pumps needed to drain them in a work published in 1588, which also shows complex geared capstans giving huge mechanical advantage, but no great strength⁹⁹.

It would have been possible to drive piles in suitable ground, whose heads could be cut off underwater, and used to support and fix in position the timbers of a grid, which would have to be largely pre-fabricated, and probably use divers for placing it.

It is however surprising that the early modern texts on construction of hydraulic works - all much later than our strict period - do not discuss the issue at all¹⁰⁰. It is perhaps a reflection of the strange fact that most texts on shipbuilding - in any age - simply do not touch on the practicalities of launching the resulting ship. In the sixteenth century it is known that Mathew Baker, Master Shipwright in the Royal dockyards was called upon as a universal Engineer, to advise on the construction of dry-docks¹⁰¹, and on harbour works as at Dover¹⁰². It seems that the tasks of building dock works and in water, and of shipbuilding, may have diverged thereafter. The first text that mentions the matter seems to be Diderot's Encyclopédie of 1751, which has an entry for cale that is worth giving in full, as an excellent summary of the problem:

Similarly records are noted for 1755, which include repairs to the site in Salvador, Bahia, before shipbuilding could start. This involved small quantities of stone, sand and lime, but also of tiles, all used by a master stone-mason. Since another entry is for painting the mould-loft (casa das fôrmas, an interesting item in itself), it is possible that the repairs were to buildings, rather than the slipway: the works were on the carreira which could mean slipway or shipyard, but no details emerge. This was a sufficiently remote site - chosen presumably for the over-riding imperative of suitable ground and slope to a good depth of water - that it was necessary to bring water to the site from a nearby aguada, the quay of the Água dos Meninos. Surprisingly only seven boat-loads of tonels and pipas were paid for during the whole course of construction of a large ship, and the barrels were repaired six times. The same source records the customary payments (propina) made to the master shipwright on keel-laying and on launching, amounting to about one-quarter percent of the construction cost¹⁰⁵.

There must be a suspicion that in an earlier period the slipways really were stopped short at the low water mark, and shipbuilding sites selected with the right slope and firm ground and no other preliminaries¹⁰⁶. The apparent absence of texts on the matter, and the drawings of Fernandes, Gaztañeta and Colbert might support this slightly surprising solution. This would go some way to explaining why ships had to be dragged afloat.

The fore-poppets

Slipways are critically important for other reasons, including what for this writer remains one of the most intriguing questions of all: why did the fore poppets (in stern launching) not collapse at the point of rotation ? The usual modern arrangement for large ships, of great length, is for the hull to be supported in a major structure, still called the fore-poppet, because the stern starts to lift long before the ship is fully afloat. Necessarily, a point is reached where the buoyancy of the stern is sufficient to lift it, transferring the remaining weight to the extreme fore end, and also rotating the hull about that fore-poppet. Many ships actually require internal strengthening at that point to get them afloat undamaged. A modern launch happens so fast and usually so remote from most onlookers, that the critical behaviour at the fore-poppet is not discernible, but failure to make sufficient provision for the geometry and load transfer involved in the rotation would lead to failure. Fore poppets collapsed dramatically at a major launch in the 1990's. The problem is not so severe with the shorter wooden vessels of the historic period, but it certainly came to prominence with longer iron and steel vessels, though this writer is only aware of one quantitative paper illustrating the problem with an analysis of the state of the fore-poppet after the launch¹⁰⁷.

In the historic period the literal fore poppets were actually a pair of single timber baulks on end. If the ships thus supported rotated as described, there would have been a great risk of either crushing or buckling collapse of the poppet, or of it simply slipping out of place. Damage to the hull might also be expected from such a concentration of load. So why does it not seem to have happened ? The risk of bits of the cradle falling away and fouling its passage is as near as we get to a reflection of the problem¹⁰⁸.

One possible explanation is that in fact the sholes and dagger planks crushed or moved enough to allow a reasonable number of poppets to share the load during rotation, or that the structure of the slipway was flexible enough to contribute to the same effect - a relative shortening of the poppets furthest inshore during the rotation. Nonetheless it is surprising that there is no more discussion of the point in contemporary texts.

Another possibility is that slipways really were not long enough to allow the ships ever to get to that point of rotation, with the stern lifting. As discussed above, especially in connection with Dutch methods, if the standing ways did not extend far enough, the hull would tend to rotate in the opposite direction as its centre of gravity moved over the end of the ways, the bow rearing. The corollary is that there is a risk of the keel striking the ground as the launch proceeded and the end of the bilgeways dropped off the standing ways. A further corollary is that such a slipway is not well-suited to hauling a vessel ashore, as the keel will tend to be below the end of the slipway. The height of tide will again be significant; coupled with the sea-bed profile off the end of the ways.

Yet again, there is a possible link to bow and stern launching, in the differential behaviour of the slender run and the full bows of typical ships, though the issues are very specific to individual ships and sites.

Cambering the ways, always setting them steeper towards the water's edge, has an interaction with this problem too, and it is conspicuous that many illustrations of early ways do show a marked camber. The potential effects are numerous, from changing or inducing rotational behaviour, and consequently controlling the maximum load imposed on the ways; making the ways shorter for the same immersion on the end of the ways; making it easier to get the keel over the ways in hauling ashore, etc. The literature on these issues for long iron and steel ships is very extensive, and each launch is the subject of elaborate calculation. One difference is that latterly the camber is likely to be of a uniform curvature throughout: that was certainly not the case in yards handling smaller and wooden vessels.
 
 
 
 

The launch of I.K.Brunel's Great Eastern, 1857-8

The reasons for referring to this seeming anachronism are several. It was a national event, for the greatest ship ever seen, with an iron hull weighing 12,000 tons at launch; it was a mixed success (for reasons which are still the subject of bitter partisan dispute), and this combination makes it probably the best-recorded launch in history. It was extensively photographed (collected most completely by Beaver¹⁰⁹). The components of the cradle and ways were elaborately tested during the design. The details of the launch process and the results of the preliminary tests are reported in Brunel's biography¹¹⁰.

There are thus important points recorded that are of relevance in understanding why much smaller ships could become stuck upon the ways. When timber ways, however carefully prepared were loaded (to perhaps several tons per square foot), and slid over each other, three things happened. Firstly there was a force resisting first movement of the two surfaces to be overcome, rather greater than sliding friction: stiction. Secondly, the carefully applied grease was forced out from the sliding surface, and unless the ship attained sufficient momentum in the first few feet it could grind to a halt (indeed Brunel's experiments showed that contrary to received opinion the coefficient of friction between the sliding surfaces actually significantly reduced above about 0.3 metres/second). Thirdly, any imperfections in the surfaces and wild grain in the timber could lead to the grains so interlocking that if a ship stuck on the ways for this reason and the bilge and sliding ways were then cut out, they could only be separated with great difficulty: they had become "wood-bound" ¹¹¹. No rope tackle would overcome this sort of resistance to movement. Thence Steel's insistence on careful preparation of the surfaces, with no projections to catch, and no weak spots in the ways or their foundations, to cause uneven loading. Brunel was well aware of these risks, and preferred to try the use of iron surfaces, after tests. It might be added that at least iron does not crush at these loadings. Despite Steel's precautions, his glossary indicates clearly enough that groundways were frequently built from decayed timbers. They were large, would have wany edge, shakes, and be quietly warping and rotting in the ground. They probably did present considerable resistance to sliding in many cases, and would crush and bind.

The ship was actually launched sideways, for various reasons, still the subject of debate¹¹². The cradles are thus slightly differently arranged from those otherwise described in this paper, but their structure is recognisably descended from earlier carpenters' work (Fig.15). There were two of them, each 120 feet long (the hull was 692 feet long). They consisted of transverse timbers under the hull, upon which three rows of poppets each side were erected, apparently using the steps between in- and out-strakes in the hull plating as dagger-planks. The daggers are all horizontal, but there are three tiers of them on the outer poppets, heavily bolted together, supported on cleats, and shored longitudinally. There is even a direct imitation of the rope gammonings preventing the poppets moving outwards under the inclined load on their heads: only in this case they were 63 mm diameter iron rods, anchored in the timbers that carried the tension under the hull. The poppets are morticed into these timbers at their heels.

The ship was finally launched with hydraulic jacks, and the resistance was reasonably well known from measurements at the time¹¹³:

initial lubricated attempt

stiction: 0.125

friction at 0.3 m/sec: 0.088

trials:

friction at 0.45 m/sec: 0.083

friction at 0.6 - 0.9 m/sec: 0.075 - 0.067

reduced lubrication at second attempt, actual ship

stiction: 0.15 - 0.167

friction, just moving: 0.117 - 0.125

friction, 0.15 - 0.2 m/sec: 0.108

The conclusion was that the critical feature was initial lubrication, for the cradle to start moving; which corresponds to the regular provision of drivers for the first impulse in old methods. Stiction had nonetheless to be overcome, and any imperfections in the sliding surfaces would also hinder the initial increase in speed that would ensure a freely sliding launch.

The key point is that, even at the height of Victorian Engineering confidence, the whole process was perceived as exceptionally difficult. Equipment and calculation alike were stretched to the limit in determining the size of cradles; and eventually the largest concentration of hydraulic jacks ever seen was assembled. Many of the leading Engineers of the day gathered to watch and learn, fully aware of the significance of the events. No comparable quantitative accounts have been found for earlier launchings of exceptionally large ships, but they occurred in all periods. The increasing size of India naus in Portugal from 1500 onwards must have presented just the same challenges to their builders.

Archaeology

There is only very limited published archaeology of actual launching ways. This arises in part from the total reconstruction of older dockyard sites, such as Deptford, the continual deepening of most permanent sites for larger ships over time or the encroachment of sites over older foreshores, and partly from the very ephemeral nature of slipways on smaller sites. Excavations at Woolwich Dockyard produced a long report¹¹⁴ including parts of a building slip, but it is fragmentary and the site was confused by redevelopments. Buckler's Hard has produced a much more intact eighteenth century site for large warships, but the last report seen was preliminary to final excavations¹¹⁵. It is known that other work has been done, for example in Amsterdam for seventeenth century sites; equally that a lot of foreshore work has been done in China for still earlier sites (possibly fifteenth century), which might include dry-docks (though the results in the only report seen by this writer¹¹⁶ are open to interpretation). Much reporting of dock features has been poor in the past, as discussed elsewhere. There is of course a substantial bibliography of work on classical shipsheds and slipways, and overland hauling, though Coates remarks that original excavations of slipways at Piraeus in the 1880's were not extended to measurements below water, significantly reducing the value of that work to archaeology¹¹⁷.

Publication is also awaited of a group of papers on related themes from the IX ISBSA meeting in Venice in 2000, which include two for Dutch and three for classical topics.

It should also be apparent that many of the details described will have left a trail of bolt and nail holes where launching apparatus has been fastened to the hull, which can be expected to appear in underwater archaeology; much as the carpenters' surmarks¹¹⁸ and ribband-fastenings from frame assembly that have already been found; or the pegs marking load-waterline that were called for in 1604¹¹⁹. It is understood that nail holes for dagger planks have been determined in the Red Bay ship of 1565¹²⁰. Steel for example refers (p49) to nogs placed to prevent the heads of shores slipping on the hull (the term more usually referring to treenails fixing the feet of shores to the slip). These will probably be treenails in blind holes, and since they worked in shear may be of large size and un-wedged; they may be at many levels, and in frames alone, or placed after planking. Groups of former bolt holes might be found through all from the spurs fore and aft in especially English eighteenth century methods.

Conclusion

The paper has shown that launching a large ship was a complex and difficult operation at any time, just as subsequent repair of that ship below the waterline was a major problem either in a home port, or at the far side of the world.

We have seen how galleys and small coasters were relatively easy to manoeuvre on rollers and greased planks, but also that when during the sixteenth century ships were more commonly built to a thousand tons and more, they had become a major problem, with no ready answer available to the shipbuilder. Such ships caused great difficulties in launching them, and the process often took many days, unless momentum took over as the ship started to move.

It seems possible that the importance of longitudinal sliding planks above the groundways had not been recognised in Southern Europe, and the articulated vasos of the old galley tradition were binding on the transverse timbers of the slipway¹²¹. Yet no English or French writers of the sixteenth to eighteenth centuries comment on the discrepancy between the originally southern method using cradles then prevalent for large ships in both England and France, and the continuing existence of some of the manifestly older methods based on sliding on the keel and bilge; nor on the actual introduction of sliding planks to the transverse system in the eighteenth century - which omission remains an unresolved curiosity. It is only in the late eighteenth century that we can be certain that sliding planks were commonly used above the groundways, other than in Northern Europe. The timbers tended to squeeze out the grease and to tear each other to bits and become wood-bound, rather than slide the ship freely in its cradle.

Nonetheless, there was a steady improvement in the design of cradles during the seventeenth century, reducing the bulk of the cradle, and increasing its efficiency. This extended to methods of getting ships ashore for repair, and may perhaps be reflected in the change from launching ships bow-first to launching them stern-first.

The other striking aspect is the absence of early accounts of adequate slipways into deep water: there is no description until the mid-eighteenth century. Several sources have drawings that almost refute their existence, as we have seen. This too must have been critical to the launching process, and to the need to drag ships afloat.

The inheritance of methods suitable for rope and muscle, and of difficulties anticipated, extended to influence the launching of the early leviathans of the age of iron and steam. The problem for the builders of India naus should not be underestimated.

This brief survey of the sources lacks contemporary evidence to answer some of the riddles: there is considerable scope for more research into such practical matters. Not least that of when and under what circumstances large ships were first launched stern-first in Portugal. What were the foundations of slipways in dockyards, were they extended far below low tide, were they straight, or just following the natural camber ? At what stage did longitudinal structure start to appear ? Does the hypothesis that the great advance in European launching methods stemmed from the late adoption of longitudinal ways stand up to wider examination ? - does Dutch evidence and that from further north and east fit the pattern.

A tentative chronology for the sequence leading to the large cradles of around 1800 might be:

Stern-first launching:

Further studies

This study has been in hand for twenty years, and has amassed a great range of material. There remain parts of Europe hardly covered by this paper, however, and this is more likely to be a reflection of the languages searched in than of the material available. The classical period has been largely omitted here, and there are whole geographic areas - such as China - where large ships have been used in the periods considered and similar problems must have been overcome, but for which there is very little information available in European languages.

It is intended to extract significant material from post-1800 sources for a future paper, not to record a history of launching as such, but to use technical material from the age of iron and steel to further illustrate the problems of an earlier age. The key topics include:

- the problems associated with natural lubricants

- growing awareness of shear strength issues, both longitudinal and transverse

- early experiences and observations with iron hulls

- and, more for amusement, some of the bizarre launchings on record.

As ships increased in length (both absolute and relative) different issues came to prominence in technical discussions:

Felipe II of Spain wrote a letter to his daughters from Lisbon, dated 19 February 1582, which has tantalising remarks on the launching of the great Portuguese galeão São Felipe. It was first published by Gachard, but more recently by F.J.Bouza Álvarez, Cartas de Felipe II a suas hijas, Madrid 1988, pp59-61. It was kindly brought to my attention by Augusto Salgado.

"I do not know what work is said there to be made here, except the castle of São Gião [below: São Julião] which is being extended, but which I have not seen since I went to Sintra. Yet another is being made in Setúbal, which I have still not seen; if I have time I will go to see it but I do not know when I will be able and, now, with the weather as it is - it is strange how it rains, it is not possible. For that reason, they took three days last week to launch a galeão into the sea. They had begun it a little before I came here, in the square of this house, where it could be seen very well, from a veranda here and was finished; they thought to launch into the water on Thursday, and we were waiting all morning; but it so great and weighs so much that it was not possible. On Friday the same happened, and we even went without Mass to see it, but it was so little possible. On Saturday also they [were] delayed (demoraram) a good while and we already had misgivings, but this time they launched it. It is pushed by hand, with a kind of chapin beneath it on which it slides. It is a thing worthy of being seen, but it would be very long to describe it here. They are beginning another, on the same site."

Chapin is not a nautical term, but a woman's clog with a cork sole, often very high. Felipe uses it at least twice in other letters (pp63, 84) in that sense. It suggests a structure of the kind illustrated by Manuel Fernandes in Livro de Traças de Carpintaria of 1616, which was an almost solid mass of timber ranged along the length of the bilge.

****

In May 1575, Simão de Miranda made a sketch (now in the State Archives of Turin) of the Ribeira in Lisbon. This shows a ship under construction (or possibly repair), which is stern to the water. A poor reproduction was published by A. de Carvalho, "Três temas sobre as relações artísticas entre Portugal e Espanha, nos séculos XVI e XVII", in As relações artísticas entre Portugal e Espanha na época dos decobrimentos, ed. P.Dias, Coimbra 1987, pp 233-257, Fig.10. A large image has been displayed at the Museu da Cidade, Lisbon. A complete but very small image is in De Olisipo a Lisboa. A Casa dos Bicos, CNCDP Lisbon, p24, and a good partial detail in N.Senos, O Paço da Ribeira 1501-1581, Lisbon 2002, Fig.12.

****

An unusual record of launching ceremonies appears in the archives of Aragon (Capmany, 1787), for 1505. D.Fernando prepared a fleet against the Kingdom of Naples. This included 9 named galleys, constructed in the arsenal of Barcelona. There is an inventory item for the powder consumed in proof firing of the single heavy bombarda for each galley and another larger one for the city, and firing 333 shots from morteretes and servatanas at the blessing and launching into the water of the nine galleys. Each master shipbuilder and master caulker received a silver-gilt cup of one mark each, which was stated to be customary. This is a relatively early record of what was later a more widespread practice.
 

Discussion from Max Planck Institut Workshop

Horst Nowacki

25 June 2002

This contribution to the Workshop, particularly in its elaborated form of the article "Cradles of Navigation – Re-Visited", is a rich source of information and a colourful account of the earlier history of ship launching. A thorough survey of the current state of the art in launching technology and on the modern level of advance physical analysis is given in Chapter XVII, "Launching", by C.M. Leavitt in "Ship Design and Construction", ed. R. Taggart, ISBN 0-9603048-0-0, SNAME, Jersey City, NJ, 1980. This may be a useful reference for any comparisons.

Launching has been recognized as a critical, potentially perilous event in a ship’s life from antiquity and is still bearing considerable risks today, which may sometimes require new, sophisticated methods of analysis. Let me illustrate that by a few further episodes.

Although we have no direct archaeological evidence of launching technology in antiquity, it is evident from the literature that the difficulties and risks involved in launching large ships were fully appreciated. Plutarch’s report on Archimedes single-handedly launching a large, fully loaded galley of King Hieron’s fleet in Syracuse by means of a system of windlass (capstan?) and pulleys certainly smells a bit of legendary exaggeration, but does suggest a certain level of technological sophistication. Another classical writer, Athenaios of Naukratis in Egypt (ca. 300 A.D.) attributes to the early Hellenistic Period also the invention of the drydock. Athenaios reports that King Ptolemy IV Philopator of Egypt who reigned from 221 to 205 B.C., among many other spectacular ships, also built a fortier galley, i.e. a ship of 40 oarsmen per half-cross section, each starboard and port, of about 420 ft length. About this ship Athenaios says (quoted from L. Sprague de Camp, "The Ancient Engineers", Ballantine Books, New York, 1974):

"At the beginning [the fortier] was launched from a kind of cradle which, they say, was put together from the timbers of fifty five-bank ships, and it was pulled into the water by a crowd, to the accompaniment of shouts and trumpets. Later, however, a Phoenician conceived the method of launching by digging a trench under the ship near the harbour, equal in length to the ship. He constructed for this trench foundations of solid stone seven and a half feet in depth, and from one end of these foundations to the other he fixed in a row skids, which ran transversely to the stones across the width of the trench, having a space below them six feet deep, and having a sluice from the sea, he let the sea into all the excavated space, filling it full; into this space he easily brought the vessel, with the help of unskilled men; …when they had barred the entrance which had been opened at the beginning, they again pumped out the sea water with engines. And when this had been done, the ship rested securely on the skids aforementioned."

Despite all necessary caution relative to such a claim without physical evidence and technical documentation, the text clearly suggests that the idea of the drydock was understood in antiquity.

As an example of the level of sophistication reached in modern launching calculations let me mention a recent paper by Stefan Krueger: "Stability of Ships on a Resilient Slipway during Launching", presented to the German Soc. of Shipbuilding Technology (STG) in May 2002. This paper deals with a large ship being launched on a single set of groundway/sliding way in the ship’s centerplane, which has certain advantages, but incurs the risk of the ship tipping sideways during the launching process. Thus the resilient, elastically and in part plastically deformable material of the ways must provide enough restoring moment to exceed any tipping moments. The resilience of the blocks in the groundway and sliding way had to be taken into account in the launching analysis using realistic nonlinear material property laws.

These comments and episodes are intended only to underscore the timeless nature of the human struggle to ensure safe launching technology.
 
 

Now for a few questions:

1. Launching Analysis before Calculus?

• The risk of tipping over the edge of the dock when the CG of the hull passes over the end of the groundways if by that time the buoyancy force acting on the partially immersed ship’s end is not sufficient to lift the ship and to pivot it about the fore poppet.
• The risk of capsizing during or just after launching due to insufficient stability.
• The risk of structural damage to the incomplete hull structure in the sagging deflection mode when the ship is partially launched.

1. Side Launchings

Response to: Questions and comments, Horst Nowacki on "Cradles of Navigation

Richard Barker, 25 June 2002

Ancient dry-docks and launching.

Dry-dock is one of the most abused terms in the field ! Any hole in the ground can be so described, it seems. (See some examples in papers such as Caravelas, tides and water). Evidence is indeed scanty from the classical world, despite the text of Athenaus. That has similarities to proposed solutions for the loading of the great obelisks onto barges on the Nile.

I wonder whether John Coates might feel there was good evidence for launching problems of classical galleys, from the infrastructure. His complaint has been the lack of interest on land archaeologists in the rather important issues of the extension of the shipshed slipways below water ! But yes, how the rather larger grain ships were built, launched and subsequently repaired is of interest, and there seems to be no evidence. If Archimedes' launching of a galley was the limit of technology, how did they launch a large grain ship ? With a lot of people and some difficulty, in short.

Calculations and precautions for launching

The first actual calculations and experiments discovered were those of Brunel in the 1850's, and the net result seems to have been to scare him into what were actually disastrous precautions. Before that, it all seems to have been very empirical - but sizes did not increase that much over a long period, and each regime would develop its own solutions. As noted in the paper, the English favoured dry-docks for large ships - though these suffered almost as many problems as launching in practice.

The record is full of horror stories about what went wrong - ships sticking, falling over (capsizing seems to be a more recent problem, possibly because launch weight had to be minimised so carefully in the past). Some of the methods collected (not by any means all in the present paper - waiting for Part II) seem utterly cavalier.

Side launching

There seem to be two circumstances where this is adopted routinely: narrow waterways, and vessel types that have little longitudinal strength. Canal narrow boats, and Great Lakes steamers fit that category. In the past, American wooden river steamers did too, with very high L/D ratios - they were sometimes just floated off in seasonal floods. One might observe that in places like the Clyde and Tees there was very little river width, but they seem to have preferred traditional methods. Perhaps the length of available waterfront was more critical.

Origins ? - down to anecdote. Bowrey hauls out sideways c.1680; various old images of Lisbon show ships broadside on in the sixteenth century; new inland waterways proliferated in the eighteenth century. Systematic information seems to be lacking.