Hedderwick: Marine Architecture (1830)



The planking is that part of the structure by which the ribs or framing timbers are covered. The planks are made from timber cut into thin pieces, of from 1½ to 6 inches in thickness — below that size they are generally called boards; they are plied completely round the vessel in a longitudinal direction, and laid close to all the timbers; their edges and ends are also trimmed in such a manner that they shall join so close to each other, that with the addition of a little oakum or other soft material drove into the seams, the water shall be entirely precluded from entering into the vessel.

The thickness of the planking should always be in due proportion to the magnitude of the vessel, particularly that of the length, it being found by experience that all ships of a long construction are more liable to strain, when lying on the ground with a heavy cargo on board, or going over a high wave, than other vessels with the same weight on board, but built on a shorter construction. It is also necessary that the planking of any ship should be of different thickness, and thickest on the parts of the vessel which are most exposed to strain, or where any particular binding is required.

The plank next to the keel, commonly called the garboard-strake, requires to be a little thicker than on the flat of the bottom, and should be perfectly sound and free from shakes, as the backing at that part is seldom so complete as the other parts of the bottom. The butts in this strake, and the one next above it, should always be placed quite clear of the pump-well, the scarphs of the keel, and steps of the masts. Those on the floor-heads and heels of the second futtocks, commonly called the bilge-planks, are in number from two to six, according to the size of the vessel; they require to be of a good quality of timber, and as long as can be conveniently worked; they should be 1-3d or 1-4th thicker than on the flat of the bottom, this being the part where the bottom and sides are first joined, and where a great portion of the weight of the ship and cargo chiefly devolves, either when lying on the ground or afloat. These planks should be close fitted to the timber, the butts well shifted, and carefully fastened. From the upper edge of the bilge-planks to the thick-stuff under the wales, all the planking on the side betwixt the foremost and aftermost square frame should be of the same thickness as that on the flat of the bottom; but it may be reduced in thickness 1-6th towards the hoodings of the stem and stern-post. The thick-stuff and wales are the next above the bottom plank; the wales are the thickest part of all the planking, and placed in the way of the load-water line to strengthen the vessel at that place. It was formerly the practice to place the wales with their lower edge about one-half the height of the midship-frame from the upper part of the keel or rabbet, i.e. near the heads of the second futtocks, which was thought to add considerably to the strength of the vessel. The upper-works and deck-binding was thus kept lighter, and the vessels being built on a broader proportion, possessed greater stability than ships on the modern construction.

The bends or wales, according to the present mode of building, are placed much higher, their lower edge at midships being from 3-5ths to 5-8ths of the height of the midship-frame from the keel to the gunwale above the upper part of the rabbet of the keel. Their breadth or depth is from 1-6th to 2-13ths of the height of the midship-frame, and the number of strakes from two to six, according to the nature of the materials and size of the vessel; their thickness, once and a half the thicknes of the bottom plank. They are generally made of the best materials. The thickness of the projecting planks is tapered off, above and below, to the size of the bottom and top-side, by sometimes one, two, or three strakes: those below are called thick-stuff, or the diminishing work; those above are called the black-strakes.

The top-sides is that part of the planking between the uppermost black-strake and sheer-plank or paint-strake. They are commonly worked narrow, and lined to a parallel breadth of from 5 to 8 inches; their thickness, for vessels employed in the coasting trade, where they are much exposed to strokes or hard rubbing, should be the same as on the side below the thick-work under the wales; but for vessels in other trades, 5-6ths of that thickness is sufficient.

The sheer-planks are the uppermost on all flush-built merchant ships, and should be made of the best and most durable quality of timber, as they are much exposed to the rot, and the whole binding of the upper-deck knees has to pass through them. Ships of 200 tons and under have but one these strakes, as broad as can be conveniently worked; vessels above that tonnage have frequently two strakes; their thickness should be the same as that of the bottom or upper back-strakes, and is commonly 3-4ths or one inch thicker than the top-sides. When there are two strakes, the butts should have a long shifting, with a scarph of 2½ or 3 feet long, in place of a square butt. These two strakes are bolted together edgeways, opposite to the opening between every other timber.

The plank-sheer or covering-board is that plank which lies on its flat, going round all the stanchions, and covering the tops of all the timbers. Its thickness should be the same as the bottom plank. It is bolted through all the timber-heads and stanchions, and downwards to the sheer-plank and water-way.

The planking on the inside of the ship is commonly 1-6th part thinner than the outside, with the exception of the binding-strakes, such as stringers, clamps, &c., which come under and above the beams, the fastenings of which come through some part of the wales or thick plank, above or below, according to the situation of the beams.

The planking of the ceiling is similar to that of the outside, with the difference only of being a little thinner, and that a shake or split in the end of a plank is considered immaterial, provided the timber is of a sound or healty quality.

Peter Hedderwick: A Treatise on Marine Architecture, containing the theory and practice of shipbuilding, with rules for the proportions of masts, rigging, weight of anchors, &c including Practical Geometry and the Principles of Mechanics; observations on the Strength of Materials, Hydrostatics, &c. with many valuable tables calculated for the use of shipwrights and seamen; also the proportions, scantlings, construction, and propelling power of steam-ships. Illustrated with twenty large plates, containing plans and draughts of merchant-vessels from fifty to five hundred tons, with mast and rigging plans; plans and sections of a steam-boat of eighty-horse power; and eight quarto plates of diagrams, &c., by Peter Hedderwick.
Printed for the Author, Edinburgh, 1830. pp 217-218.

Transcribed by Lars Bruzelius

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