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Clipper Ship Plans


Wooden

The British-built Clippers for the Tea Trade had an advantage over the American in that their designers knew what the intended cargo was and could estimate its weight and centre of gravity beforehand, allowing for some slight variations in weights of different Teas, and they could therefore design more precisely

 

In the early 1840s Aberdeen had produced a new type of bow on small coastal schooners which had similarities to an American development and which, later in the decade, was being incorporated into Tea Trade ships, but it was the repeal of the Navigation Act which was instrumental in bringing much greater urgency to improving design. With the British ports now open to free competition, the Americans wasted no time in seizing their opportunity. Their Clipper Oriental built in New York 1849, made her first voyage to Hong Kong and back to New York, the homeward leg taking 81 days. Her next trip back to Hong Kong took 80 days and some hours, which feat aroused the excited interest of British traders there, who immediately chartered her to take Tea to London, where she arrived 97 days later, making a triumphant entry into the West India Dock on December 3, 1850 .  The whole nautical community was aroused with admiration for this magnificent fine-lined vessel, and no little uneasy at her threat to British ships. In dry-dock at Blackwall, the home of the East India men and their successors the Blackwall Frigates, Surveyors and Sipwrights took off her lines, a practice which had been carried out many times before with captured American or French ships noted for their speed and good sailing qualities, as later the lines of the yacht America and clipper Challenge were also taken off.  The only British sailing ship builders who had attracted any attention by experimenting with a new hull form and had achieved any noteworthy improvement were at this time located in Aberdeen, Messrs Alexander Hall and Messrs Walter Hood, and it was to these builders that owners turned to meet the American threat. The Stornaway and the Chrysolite, built by Halls in 1850 and 1851, were the immediate reply to the Oriental, the previous study of whose lines in London resulted in the Blackwall Challenger, built by Greens of Blackwall in 1852.

The after ends of the clippers were also subject to much experimentation in their form below and above the waterline both for speed and seaworthiness. A good clean run, if carried too far forward, could result in the form above the waterline being too fine also, and the consequent lack of buoyancy result in a following sea engulfing the stern before it had sufficient lift to rise out of it. A notable ship with this tendency was the Ariel built by Robert Steele's of Greenock in 1865. If handled carefully, the slimness of her stern could be offset somewhat by shortening sail on the mizzenmast when there was any danger of being pooped. However, there were a number of occasions when she was pooped, and after her disappearance in 1872 it was conjectured that following seas had washed away her helmsman, causing her to broach and founder. The illustration below of this possible occurrence will give some idea of the dangers to which a number of Steele's vessels were subject, even if the incident itself is in doubt.

The grace arid beauty of, the clipper ships was achieved by men who had an intuitive instinct for good aesthetic taste, influenced by the nature of the material with which they worked.  Wood can be carved into grotesque shapes, but it cannot be bent into ugly bends and curves without damaging or rupturing the fibres, and in consequence shipbuilders throughout the ages have used the natural tendencies of the wood to achieve their ends.

A vessel such as a Viking ship was not designed beforehand to have beautiful sweeping curves: the shape was the result of the natural bend and twist of the planks with the minimum of cutting away and tapering until the eye judged it to be right.

 

 

 

Many of the Shipyards devoted to wooden construction lay in remote areas where the majority of the townspeople were employed in the yard and took a great pride in their inherited skills. There was a minimum of Shipyard equipment in the way of machinery. Sawing off logs was done by hand with pit saws; blacksmiths or brass finishers were the only metalworking men in the yard; and along steam chest was the only aid for shaping planks. When one of these yards closed down, there was little left after awhile to indicate that there had ever been an establishment capable of building these complicated structures, apart from maybe a small brick-built general office and some wooden shacks. There were no overhead travelling cranes or steam engines to move material about in those days. Stern frames, plating, etc. for iron ships were swung into place by rough tree trunks lashed together into a sheerleg and equipped with hand-working tackles, a system used well into the 20th century in many yards. Material was moved by hand bogies which were sometimes on rails. A large man sting crane or derrick, possibly with a steam winch, would be in the area for general use if the yard did not have one of its own.

With educational facilities no more than a local schoolroom, which, however, taught well the basic 3 Rs, there was little opportunity for the working man to learn anything beyond his inherited trade. In consequence, although the introduction of iron shipbuilding had been effected quite early in the 19th century, and its merits had become fairly obvious, many shipyards could not undertake to make iron hulls because of the lack of experience of the workers, who were also naturally reluctant to give up their trade of wooden ship-wrighting.

 

 

 

 


Composite

While iron ships were inexorably superseding wooden ones, and supplies of good timber were becoming more difficult to obtain, there appeared on the scene a compromise which for a brief period was to produce the finest tea clippers ever built. These were the composite ships, which had a basic skeleton of iron covered by a wooden skin. Many combinations of iron with wood skin structure had been tried in the early part of the 19th century; also iron beam knees, then iron beams, and next iron beams and iron upper frames, but all with wooden skins which could also take the copper sheathing so much in favour for speed.

It was this latter fact which provided some shipowners with an excuse not to go all out for an iron hull, which of course could not take copper sheathing. Speed of building and cost also often influenced the decision. Those shipbuilders whose yards could not be economically converted to build complete iron hulls  were also glad to take up the challenge.

The Baring Brothers Archive - Marine Designer's drawings in pen and ink, marked W. Rennie, of a composite clipper ship viz - Norman Court. Scale: quarter inch to one foot; with a list of principal dimensions.  The drawings are: sheer elevation, body plan and half breadth plan. Endorsed: Norman Court 5. c1869: Architect’s drawings in black and red inks, with watercolour wash of midship section of clipper ship Norman Court. Scale: three eighths of inch to 1 foot 6. No date: Naval Architect’s drawing in black and red inks, showing a plan of cabin and living accommodation aft for an unspecified ship (Norman Court?); showing positions of furniture. Scale not stated - Marked ‘W T Young, 40 Penny Fields, Poplar, London, E’ 
Naval Architecture was still being taught at Poplar Technical College in 1962.

Payments include: to A & J Inglis for the ship herself; to William Rennie for the builder’s model; to Mr Wyon for drawing heraldic arms; to Captain Shewan for salary and travelling expenses; for provisions and other expenses in Glasgow; for towage and Pilotage on the voyage from Glasgow to London

Midship Section
Marine Designer’s drawings in black and red inks, with watercolour wash of midship section of clipper ship Norman Court.

A few composite clippers were being built in 1869 and continued with the earlier ones to struggle for inferior Tea cargoes, which they carried to the American shores, Australia, and at intervals to England, until about 1886, the Halloween being the last. Their life was not over, however, and with the addition of the new iron clipper the Wool and Emigrant Trades to Australia and New Zealand still proved economical enough to keep them going, and on occasions to outpace their propeller driven rivals, even with rigs much reduced from those carried during the peak of the Tea Trade. One or 2 managed to earn a living into the next century, the Cutty Sark being an obvious example.


 

Bulwarks and Stern
As to her deck fittings, her bulwarks were panelled in teak, with a solid brass rail on top all round.  Even her foc's'le lockers were panelled better than those of many a ship's cabin. 

Norman Court, indeed, rivalled the Robert Steele Clippers in looks and beauty, and was considered at one time to be the prettiest rigged vessel sailing out of London.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hull Strengthening
The floor timbers are moulded 21 inches on the keel, and sided from 12 to 13 inches, and over them are 4 tiers of midship keelsons, each 16 inches square, and on each side of these are 2 depths of sister-keelsons, of the same size, the whole scarphed and keyed, and fastened with 1¾ inch bolting, the bolts not more than 8 inches apart. The whole frame, fore and aft, is diagonally cross-braced with iron, 5 inches wide, 7/8ths of an inch thick, and 38 feet long. These braces are bolted through every frame, and through every inter-section; are let into the timbers and ceiling, and extend from the 1st futtocks to the top-timbers.

Bracing, Stringers and Frames

In all these systems the keel, stem, sternpost, and usually the waterways were of wood, with the side framing, floors, keelsons, stringers, sheerstrake, deck beams, diagonal straps and deck tie plates of iron. The greatest problem was to avoid contact between the copper sheathing and any ferrous metal where salt water could touch both and set up an electrolytic action. For this reason Lloyd's suggested that the bolt fastenings of the external planking be made of yellow metal or copper. If of iron, preferably galvanized, the external heads had to be sunk below the face of the planks and covered with a wooden dowel or cement mix and in addition covered with a minimum of 1.25 in. of wood sheathing on top of hair felt. These latter measures could considerably alter the lines of the hull and the displacement. Internally, with the Jordan system, the bolts were tightened up directly on the iron frames, but if of copper or yellow metal they were insulated to some extent by a coating of guttapercha or red oxide paint. Despite the fact that bilge or condensed water could make contact with these fastenings, they seem to have successfully stood the test, as those on the existing Cutty Sark bear testimony.

 

 

 

 

Keelson Details

Witch of the Wave Lines


 


Iron Hulled Clippers

The main advantage of the iron hull was the increase in internal volume, the structural members being so very much smaller. Other advantages were that the stem bar, being a continuation of the iron bar keel, was much sharper than the wooden stem, being only about 2 in. thick. The increase in strength and the greater resistance to fire were obvious, but durability remained to be proved. The disadvantages as expressed by the critics, apart from the possibility of poor workmanship such as in riveting, were for the most part biased. It was claimed that the iron hull sweated to the extent that it damaged cargoes, especially in the case of Tea. However, in the Composite system of construction, which achieved its peak with the Tea Clippers, the decks were constructed precisely the same as on the iron ships, that is, with open exposed beams bound together at their outer ends by stringer plates and with longitudinal and diagonal tie plates elsewhere, all being covered by the deck planking. The iron-plated hull side could induce some sweating, but this would drain down between the frames and behind the sparring battens clear of any cargo. Hold ventilators of the cowl type were also introduced on metal hulled ships some time before they were used on wooden ships, and considerably alleviated the sweating problem. The wholly wooden hull also had its disadvantages, as the strain from the rigging when heeled over opened up side and deck seams and caused leakage of salt water; the moisture from sweating was at least distilled water.

However, some far-sighted Scotsmen saw the necessity for starting shipyards from scratch, equipped with the necessary machinery for iron plate and angle work, and with men specially trained for this work alone.  The traditional shipwright was still necessary for decks and many parts of the ship's structure and for the lining off and mould loft work. Demarcation of work was always a sore point, no man, understandably, being willing to see his traditional function usurped, and it was finally agreed that shipwrights would actually mark out the metalwork and make the templates for it. Demarcation of work was such that, for instance, a plain wooden rail, simply rounded off at the edges, would be a shipwright's job, whereas if the edges were moulded to a fancy shape they would become a ship joiner's work. This may seem to be splitting hairs to those whose job has never been encroached upon, but usually when new methods or materials are introduced into a work procedure, a sensible consultation well beforehand can settle any differences, whereas a sudden presentation of such a situation with a loss in earning power for someone will cause trouble.

Two of the far-sighted Scotsmen mentioned were John Laird, who established a shipyard on Merseyside at Birkenhead, and William Fairburn, whose yard was on the Thames. This was in the 1830s. The banks of these 2 rivers became the main centres for iron shipbuilding, with the Clyde and most of the Northwest coast shipyards following soon after.  As early as 1838 an iron sailing ship, the Ironsides, had been built in Liverpool, followed intermittently by others. On the Northwest coast a handsome iron schooner, the Lowca, was built by a Cumberland Iron foundry in 1843 with such enthusiasm that she was practically all iron, masts and rigging as well as hull. She was the first vessel so rigged to round Cape Horn. Wire rigging did not become general on the clippers until the 1860s.

The earliest iron hull plates were very small by today's standards, no more than 6 ft by 2 ft 6 in. by approximately 3/4 to 7/8 in. thick, and with about 18 in. frame spacing; the arrangement of butts was like bricks in a wall (23). By the 1860s the plates had increased in length to a minimum of 9 ft and butt joints were spaced at least one frame space clear of each other . Each strake of plating was still very narrow, between 2 ft 6 in. and 3 ft wide, which meant easier handling in erection and a minimum of shaping.  Shaping to the hull form was done by passing the plate between rollers which could be adjusted to vary the amount of curvature at each end without any compound curves. Any compound curves necessitated the plate being furnaced until red hot and then quickly hammered to shape over iron-strapped template formers. As soon as the plate was withdrawn from the furnace, a gang of men attacked it with heavy hammers, like demons from hell, with red-hot sparks flying in all directions. The plate might have to be furnaced a 2nd time before the correct shape was made. This process was expensive and kept to an absolute minimum, usually only 2 plates being involved, called 'oxter' plates, from their similarity to the armpit, their situation being under the counter just forward of the rudder hole.

The greatest difficulty in early ironwork lay in the bevelling of the outer flange of the angle iron frame. This also had to be done while hot, the bevel being in a twisted form to suit the hull lines, which varied from end to end of the length of frame. All too often this was badly done, being a difficult operation, with the result that the hull plates did not lie truly flush against the flange for tight riveting, and numerous iron strips or liners had to be inserted to fill the gap. Rivet holes were frequently punched too close to the edge of the plate or out of good alignment with each other . These were some of the well-founded reasons why the iron-hulled ships were slow to receive widespread approval, and Lloyd's were slow also in granting them a good class. This lack of approval or classification for a short term of years caused resentment in the Liverpool area as the Merseyside yards did for the most part produce excellent work, and Laird's on the opposite bank of the river were acknowledged to be masters at the craft.


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Last modified: 01/09/2013