While almost the entire construction of a First Rate was from seasoned oak, the keel was usually made of elm, a material which better withstood constant immersion in salt water and was available in long straight lengths; the lengths were laid upon blocks which formed the slipway, set with a declivity (or incline) to the water of between 1 in 12 and 1 in 16, or horizontally if built in dry-dock. They were scarphed (or joined with overlaps and then bolted) together to form a continuous spine over a hundred feet long; in the very last First Rates, this keel length had extended to over 200ft following the radical redesigns introduced by Seppings. The keel ended towards the rear of the ship in a straight sternpost, which usually raked aft, preferably cut from a single length of first-class oak. At the other end of the keel, the stem was a curved section which began horizontally as a continuation of the keel but gradually turned until it ended in a vertical member at the ship’s head.

The frames, which formed the rib-like skeleton of the ship, were set at right angles to the keel on both sides, consisting of curved (or ‘compass’) timber which began horizontally and then curved to rise up to form the side structure of the ship. These frames – strictly speaking, ‘framed bends’ – comprised several overlapping sections scarphed together in pairs, the first forming a floor and the curved pieces forming a series of futtocks. At the height of the various decks, deck beams were fitted to the futtocks, their ends supported by brackets called ‘knees’, set vertically (hanging knees), horizontally (lodging knees), or diagonally (dagger knees). The beams were cambered (rounded up), so that their centre was several inches higher than at the sides, so that water would run down to the sides and out through the scuppers. A wide variety of pillars, riders and other additional pieces of timber were fastened to add strength and rigidity to the ship by locking the main members together.

THIS is the framing draught for the Caledonia as designed (1796) but includes later modifications like the built-up bow. The production of a complete scheme of framing became more common as the eighteenth century progressed, augmenting but not replacing a written specification of the sizes, shapes and scantlings (sectional dimensions) of the timbers to be employed. Careful analysis of this draught reveals the complicated pattern of framed bends, with their overlapping futtocks, separated by very narrow vertical gaps. The frame plus one ‘gap’ was an important unit – called ‘room and space’ – in the structural plan of the ship, and a major determinant of ultimate strength. On this draught the newly introduced ventilation openings are emphasised in magenta ink.
[NMM J1951]

Externally, the lowest line of planking was the garboard strake. This was followed by the bottom planking, and then by diminishing strakes as far as the main wale. The wales were strakes of heavy and thicker planking which ran along the length of a ship making an important contribution to the longitudinal strength of the ship. On a three-decker, there were three wales: the lowest – the main wale – was generally composed of two separate strakes from about 1650 until ‘closed’ (made solid) in the mid-eighteenth century, situated between the waterline and the lower edge of the lower deck gunports; the middle wale (peculiar to three-deckers) was found between the lower and middle decks; the uppermost or channel wale was generally composed of three strakes of heavy planking, generally between the middle and upper deck gunports. As the name implies, the channel wale (or ‘chain wale’) was the timber to which the chains from the shrouds were secured – the shrouds were the main standing rigging providing lateral support for the masts and to give them maximum spread they were carried down to platforms, called channels, extending from the ship’s sides.

ROT and decay were major enemies of wooden warships, to which the only answer was the use of seasoned timber and the careful ventilation of the structure, which also contributed to the health of the crew. From the 1790s, ventilation shafts were built into the very framing of British warships, as shown in this detail. It is annotated: ‘A sketch of the frame of the Hibernia 100 guns building at Plymouth, showing the manner of framing the openings between the timber (for all three-deck ships) for carrying off the foul air below – a copy of which was sent to Plymouth for the above ship 6th March 1802 – another to Woolwich for the [Second Rate] Ocean (except a little variation occasioned by the disposition of the frame), 6th March 1802.’ The sectional sketch on the right also illustrates well the high degree of tumblehome – the inward inclination of a ship’s side from its widest point around the level of the lower deck up to the narrower width at upper deck level. This narrowing as the side rose contributed to the stability of the ship, so that it was less likely to roll heavily.
[NMM J0805]

Originally these channels were located below the middle deck gunports, but after 1703 the reduction in tumblehome (the inwards inclination of a ship’s side as it rose from its broadest part around the level of the lower deck) meant that the fore and main channels could be raised above the middle deck ports, making them less exposed to damage in high seas. The mizzen channels were always one deck higher than those for the fore and main shrouds, but in 1745 the main and fore channels were again raised, this time above the upper deck ports; a decade later they reverted to their previous location. However, in the 1780s these channels were again moved above the upper deck ports, probably commencing with the Royal George of 1756, and remained so for the rest of the sailing era. Finally in 1803 the mizzen channels were moved again, this time to above the quarterdeck gunports.

Overall, enormous quantities of timber were required for the construction of a First Rate. The quantity naturally rose as the size of such ships grew over the centuries, but – as an example – the Royal George of 1756 needed 288,025 cubic feet of timber (defined in timber merchants’ terminology as 5760 loads’ of timber, a load equating to 50 cubic feet); the next First Rate, the Victory, required over 300,000 cubic feet. The majority of this timber was compass (curved) or straight oak, but elm was required for the keel and such planking such as the garboard strake, and fir, pine or spruce for the masts and spars.

It was essential to protect the hull of any wooden ship from deteriorating when immersed in seawater, where is was liable to rot and to be attacked by marine boring creatures or barnacles and other life-forms which would encrust the hull and reduce sailing performance. The problem of rot was countered by avoiding ‘green’ or unseasoned timber whenever possible, and interior ventilation systems were gradually introduced. From the time that warships began to serve long periods in tropical waters, where boring by teredo worms was a major menace, various compounds were used to sheath the hull, generally a mixture of horsehair, tallow and sulphur, which was deemed poisonous, and light ‘sacrificial’ exterior boards. However, lead sheathing was experimented with from 1674, and abandoned as impractical, but the eventual solution was discovered in the early 1770s when copper sheathing became a regular feature. This required many thousands of individual copper plates (almost 4000 were used for the Victory of 1765, each 4ft long and 14in broad) to be fastened to the planking with copper nails.

Such attempts were not new: from the late seventeenth century onwards designers like Anthony Deane and Edmund Dummer, and more recently the East India Company’s Surveyor, Gabriel Snodgrass, had struggled with methods of making wooden hulls more rigid. Many had tried various forms of diagonal or cross-bracing, but from 1811 Robert Seppings worked on a complete system he was to call the ‘trussed frame’, which was based on an interlocking set of X-shaped riders fitted along the insides of the hull. Initially used to repair old and hogged ships, its advantages in terms of strength were quickly appreciated for new construction, and his methods quickly became the standard after he was appointed a Surveyor of the Navy in 1813 in place of Sir William Rule. There were many other improvements in the details of construction which in total added greatly to the structural strength of ships, allowing the rapid increase in size that characterised the last generation of sailing warships. Seppings also improved the design of the bows of ships and completely remodelled the stern, making probably the largest contribution by any one man to the final years of the wooden warship.

WITH the increasing scarcity of natural crooked timber for the all-important knees that fastened the beams to the hull sides, attempts were made to replace them with iron. Different designs were tried but eventually Thomas Roberts’s wrought iron plate knees became standard. Both hangings and lodging knees were replaced by a chock under the beam and plate knees bolted to either side, as shown in this three-view sketch from 1807 of the Caledonia’s orlop and lower (gun) deck beams. Note that the plate includes an L-shaped bracket (visible in overhead and end-on view) that performed the function of the old lodging knee. [NMM J1955]

THIS profile draught of the Britannia, dated January 1815, is one of the first to show the full gamut of Seppings’s new structural system, and in particular the extent of the diagonal trusses. It is signed by the Surveyor himself. Its novelty required the main elements to be keyed for the shipwrights using the draught. The new round stern is also indicated.
[NMM J1959]

In the bow of the ship, the bowsprit was a long spar rising through the base of the beakhead bulkhead at an angle of between 30 and 36 degrees to the horizontal; the angle increased during the seventeenth century, but was much reduced in the eighteenth. The length of the bowsprit was almost as great as that of the foremast. The heel of this bowsprit was sited on the lower deck, close to that of the foremast. A vertical mast (called a spritsail topmast) was mounted on the end of bowsprit in the seventeenth century, carrying an additional square sail, but this was abandoned in the eighteenth century and instead an extension of the bowsprit, known as the jibboom, was added, and by the early nineteenth century a further extension, the flying jibboom, had been added. The bowsprit and jibboom carried yards (and hence square sails) fastened below them in the same way as the vertical masts, but they fell into disuse with the introduction of fore-and-aft jibs and staysails set from the bowsprit and its extensions.

A midships section of the Caledonia showing how the angle between the horizontal and vertical of the iron knee varied depending upon which deck level they served. This required virtually every knee to be individually wrought for each position, removing the potential advantage of mass-production; it may also explain why so apparently obvious an improvement had not been adopted earlier.
[NMM J1953]