- The background to the tea trade
- Chinese silver
- Treaty of Nanking
- British-built clippers
- Ocean Steam Ship Company
- The homeward passage
- Development of the ships
- The way of a ship
- A comparison of hull forms
- Development of the clipper bow
- Development of the upper stern
- Headworks and upper stem
- Disadvantage of Aberdeen clippers
- Comparison of sizes
- Hull Construction
- Construction of iron hull
- Composite construction
- Proposed tea clipper
- Ornamental deckwork
- Ornamental deckwork
- Miscellaneous fittings
- Full deck height poop
- Sail plans
- Details of tops
- Masts and spars
- Iron yards
- Steering Gear Arrangements
- Windlass and Forecastle Arrangement
- Fife Rails and Bitts
Headworks and upper stem
She was a large ship, 230 ft long by 43 ft beam. Most of the American clippers then being produced were large compared to their British counterparts.
As a result of the short and narrow stem knee on these later American clippers, the gammoning which held down the bowsprit was altered. The old method, and that still used on British clippers, was to have a long slot in the stem below the bowsprit, through which a chain was passed and lashed around the bowsprit with several turns, each turn crossing the next from forward to aft in a crisscross fashion, and each turn being nailed either to the stem or the bowsprit if of wood. With this arrangement went a single larger chain bobstay from the stem to the bowsprit end. The American knee, however, was weaker in substance to take a slot and chain gammoning which would also be in way of the figurehead, so a strong iron strap was used instead, which was passed over the bowsprit at a point behind the stem line and only its bolts exposed just outside the stem planking. This was not quite as effective in position as the chain gammoning, being nearer the heel of the bowsprit, so it was usual to introduce two bobstays from the stem to help hold down the bowsprit.
Another rising star in the shipbuilding world, Donald McKay, had come down from Nova Scotia in 1826 to work with Brown & Bell and Isaac Webb in New York as a shipwright and no doubt was absorbing the revolutionary developments around him. There were no schools of theoretical naval architecture for merchant shipbuilding at this time, nor for many years later, and the only training to be had was in practical shipbuilding, mathematics and geometry. It was left to an intelligent and inquisitive mind to use this basic background to best advantage, coupled with practical cumulative experience, which was the path that McKay trod. John Griffiths was one of his teachers. By 1840 he was in a partnership at Newburyport, Massachusetts, building and designing a variety of successful craft, until he was persuaded to go to East Boston in 1845 where he commenced building fast packet ships. The shipbuilding industry in Boston was lagging behind that of the enterprising and energetic New Yorkers, one reason being that Boston merchants still insisted on fuller lines for good carrying capacity. Eventually by the 1850s, the renown of the New York built ships was such that Boston had to take up the challenge, and McKay and a younger man, Samuel Pook, were the leading lights in developing the wonderful clippers that sprang up in many yards along the East Coast. McKay's clippers, although keeping to the clean bow as on the later New Yorkers, tended to retain a longer stem knee and featured a form of decorative headboard which was built flush with the hull without exposed timber supports, and looked very handsome.
The American clippers kept to a square transom type of stern much later than the British, although the Challenge was built with a large, deep semicircular counter with about four mouldings of concentric diminishing arcs. Many of McKay's sterns were similar.
The great length of these clippers brought about problems of longitudinal strength which were countered by making the outer keels and inner keelsons of considerable size. Internally, the keelsons were built up of enormous timbers laid side by side and extending upwards also, to such a height that they resembled longitudinal bulkheads. Together with large wooden knees from the centreline pillars, and at the sides also, the space lost contributed much to making these ships uneconomical in later years. Their bulwarks, which in normal shipbuilding practice are not designed as a strength factor, in this case were built high and exceptionally strong, the uppermost rails being heavy solid timber (clamps) from end to end, and the planksheers and waterways also of great sectional area. By comparison, the British style of bulwarks was flimsy, and whole sections were often swept away, although they were normally adequate for their job. Bulwarks, both British and American, often had more sheer forward than the deck. The much deeper keels of the American ships, although primarily for strength, contributed resistance to lateral drift or leeway.
In addition to these precautions for resisting bending strains, the Challenge was reputed to be the first American vessel to use diagonal iron plate straps across the outer face of the frames and under the planking.
One of the most significant changes which the refined bows of the clipper ship brought about, however, was in the sheer. This curvature, like an arc oflarge radius, had from earliest times been set with its tangential point to a level line some distance forward of amidships, which resulted in the poop being higher than the bow at deck level. With the sharper bow, however, and its tendency to sink deeper into a sea, the fore end of the ship needed to be increased in height and this was achieved by first bringing the tangential point to the middle length and eventually well aft of it. The actual amount of curvature was about the same as before, but the bow was higher than the poop, which radically changed the whole aspect of ships such that at a distance it was apparent even if the fullness or slimness was not. This is most noticeable in films of old sea classics, where necessity has demanded the use of a modern sailing ship hull faked up with a high oldfashioned poop. The original sheer lines can still be seen, which give the old-tiller the awkward appearance of squatting by the stern.
The building of true clipper ships in America covered only a short period, approximately from 1845 to 1860, after which time the need for their extreme slim lines no longer existed, and in the following years the sailing ships built were much reduced in rig and capable of carrying a more economical cargo with fuller lines.
In Britain, meanwhile, a parallel development had been going on, in which the change in tonnage assessment in 1836 while encouraging a better form of ship with less draft also allowed inventive minds to gain an advantage by increasing the length above the waterline, particularly in the bow, which gave a slight increase in capacity without increasing taxable tonnage, as against a ship with a straight stem. This elongation of the upper stem, introduced in 1839 on wooden ships by Halls of Aberdeen, was known as the Aberdeen bow and was incorporated in a schooner called the Scottish Maid which attracted much attention among the owners of the prospective tea clippers.
It was essentially similar to the bow which the Americans introduced. In itself, it did not make a fast ship under moderate conditions of weather . The advantage lay in the ability to drive harder into rising seas without the sudden check and shock which a full-bowed ship encountered. The old timers had to reduce sail to prevent damage to the fabric of the ship, whereas the clippers could carryon much longer until they too reached a point where the whole stem would bury itself and sail would have to be reduced and the course altered.
As to who was responsible for first introducing this refined bow, both above and below the waterline, it is difficult to say. References to it are usually confined to its evolution in wooden ships. But the development ofiron ships must also be taken into account, and power driven hulls. Here the evolution arose from more practical structural reasons. The manufacture and shaping of iron plates leads to a straighter and sharper form of bow, the easiest termination being a straight upright stem. If for appearance it had been desired to keep the overhanging concave curve of stem with the ease of construction of the straight termination of plates, the overhanging projection would have to be carried on in a thin flat plate the same thickness as the plate keel, which would not be a practical proposition. Therefore the upper stem plating was shaped to extend to the curved stem bar, thus arriving at the same result as the wooden stem in both the American and Aberdeen bow. The full development of this can be seen on drawing (15) with the Lord of the Isles of 1853, an iron tea clipper which probably derived her form from steamships, a form which persisted until the later days of the sailing ship with varying degrees of fullness.