Hedderwick: Marine Architecture (1830)


Planking the Bottom. — The flat of the bottom from the garboard-strakes to the bilge-plank, and the part of the bottom from the bends downwards, may either be planked or left open for the present, as may be considered most convenient. When the timber is green, and requires seasoning, it is most proper not to cover in the bottom too soon, but to carry on some other part of the work in the meantime, as to get in the deck-beams or the like. But at all events, supposing the timber to be quite seasoned, two strakes in the flat of the bottom, and one above the bilge-strakes, should be left out, in order to keep the ship clear of spales and borings until the inside work is finished.

There are various opinions respecting the method of planking the bottom, some preferring to work from the bilge upwards — others to begin at the wales, and work downwards; those of the latter opinion supposing that they work themselves sooner out of the snying of the plank by having the round edge of the plank to work upwards. But this is only supposition, for the plank must be of the same form, and have the same snying, whether you work upwards or downwards. It is no doubt true, that by making inferior work, a little will be gained by working downwards, as by having no seam to confine the planks below, they may be kept a little fuller on the luff of the bow, and whatever they want of being set close to the seam above will be in favour of lessening the snying of the next plank under; at the same time, it is by no means an equivalent for the difference in the quality of the work.

In working upwards, when the plank is hooded, and when you are bending it round to the timbers, its own weight will assist greatly in bringing it down to the seam; then, by keeping it close to the timbers, at the same time that you are setting it down to the seam, the upper edge of the plank below will prevent from leaving the timbers at the lower edge; whereas, in working downwards (where you have to set the middle of the plank upwards), the lower edge of the plank is free, and from having a tendency to fly from the timbers, which is increased by the action of the wedges employed to set the plank up to the seam, it is more laborious to make good work. In my opinion, planking upwards is preferable, for it is certainly easier to set the after end of a bow-hooding down, than to set its middle upwards. It is, however, very common, when the wales are put on, to work two or three strakes downwards (and it is not the least objectionable, if proper attention is paid to make good work), than to work upwards from the bilge until you close in. Supposing you begin at the wales to work on the diminishing strakes, which should all run round the bow to the stem if possible, line their breadths on the timbers; supposing them amidships to be 10 inches, they should not exceed 4 inches at the hoods. Let two or three of the strakes immediately under the thick strakes carry their breadths well forward, in order to take off as much of the snying as possible. For if the ship has a full harpin and a fine entrance below, all the planks in the bow will have a very considerable round upwards in the middle, although they appear to have it the opposite way when the ship is in the water. When not provided with proper planks to work the bow-hoodings from, it will be nearly impossible to bring them all to the stem; and if it be attempted, so much setting the edge way will be required, that several of the planks may be sprung; it will also be with difficulty that you will be able to work or keep them close to the timbers at the lower edge. Therefore it is much better to work one or two of the upper strakes short of the hoods, making what is called a stealer, allowing the strake under the thick-strakes to butt 4 or 5 feet short of the hoods, which will bring down the luff of the bow and straighten the edges of the planks under, so that they will be easier worked to the timbers. This method is allowed to make better work, but not to look well on vessels that are not to be copper-bottomed. When it is intended to run all the strakes forward to the hoods, continue to place the butts in the bow, so as to divide the snying as much as possible, which may be so contrived as to assist the working of the plank, without being injurious to the vessel by destroying the shiftings of the planks.

Having worked a few strakes round under the wales, being at the bilge and work upwards, until you close in, only leaving out the strake next the bilge-strake, to allow the clips to fail [sic] through during the time of dressing and working the inside work.

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 284-285.

Transcribed by Lars Bruzelius

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