Hedderwick: Marine Architecture (1830)




On Launching Vessels whose Bottoms are coppered on the Stocks. -- Ships are frequently built at places where there are no dry docks, nor even any convenient place for laying them on the ground, so as to get the cleats, which are nailed on the bottom for securing the heads of the proppets, &c. belonging to the bilge-ways taken off; in which circumstance, if the vessel is to be coppered, it must be done upon the stocks. In this case, you must attend strictly to the caulking. The whole bottom must be carefully examined and made perfectly tight, and the coppering completely finished, before preparing for launching; and lastly, the launch must be so contrived that every thing connected with the bilge-ways shall stand independent of any fastening or cleats to the vessel's bottom, which would destroy the copper. There are two or three ways by which this may be effected -- as by binding the heads of the proppets by chains passing from the one side to the other, under the bottom, connecting them in such a manner that they can be disengaged when the vessel reaches the water, to allow all the launching material to be hauled from under the bottom. To do this properly, you must nail a stout piece of plank along the heads of the proppets outside and in; bore a few auger-holes through these planks; also have locking-pieces on the outside of the planks, and through these holes pass a chain doubled, so that the bight of the chains from either side may meet at the keel; put the double of the one chain up through the bight of the other from the opposite side; haul them tight, and put a bolt through the bight of the chain, which is rove up through that of the other from the opposite side. The chains may then be set up tight, with wedges drove in betwixt the locking-pieces and the planks on the sides of the proppets. The bolt for locking or connecting the chains together should have an eye, and a rope taken from it on board the vessel either over the bow or stern, so that when she is fairly off the ways, the bolt may be pulled out between the bights of the chain, and the bilge-ways and proppets allowed to float out from under her bottom.

The proppets and bilge-coads may be also from flying out, by nailing a stout ribband along, to prevent them from flying forward or aft from the inclined surface of the bottom, and fixing 3 or 4 stout ring-bolts in the bilge-coads at the upper and lower end, the foremost one opposite the foremost proppet or so, and the aftermost one at the lower end of the bilge-ways, opposite the aftermost proppet. Put ring-bolts through the ship's bow and quarters above water-mark, right above those on the bilge-coads; the ring-bolts for the vessel's bow and quarters must have their heads made in form of a crook or dog-bolt for a windlass, the crook being about 1½ or 2 inches in length, and very strong at the neck; the rings must also be strong, and pretty large in diameter. When the bolts are driven in through and locked up properly on the ceiling, and the ring-bolts in the bilge-coads locked on the inside of the same, procure a few stout pieces of timber for wrung-staffs, of sufficient length to reach from the ring-bolt in the bilge-coad up through the ship's quarters; and having put one end into the ring at the bilge-coad, and the other up against that in the vessel, slip on the ring over it and the crook. Having secured three or four of these on each bow and quarter in the same manner, fasten a stout piece of timber on their inner sides, and opposite to the plank or ribband on the heads of the proppets; then between these set in short pieces of timber for shores, and wedge them all tight up, which will completely prevent the heads of the proppets f[r]om flying out when they receive the weight of the vessel. The use of having the ring loose from the bolts, and to ship on the crook of the bolts through the vessel's side, is, that it may be easily unhooked, and allow the wrung-staffs to be disengaged. These rings must be fastened to the end of a small piece of cord, to prevent their being lost by falling into the water when they are tripped off the crook by the floating up of the vertical pieces, along with the bilge-coads, proppets, and other timber employed for the filling-up of the launch.

Lastly, the heads of the proppets may be secured from flying out, by first laying two or three short logs of timber twartship-ways, with their ends under the vessel's keel, and the other projecting out over the top of the bilge-coad for 5 or 8 feet. From the outer end of these, diagonal shores may be placed against the ribband on the head of the proppets, which of course will completely prevent them from flying out by the pressure of the vessel.

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 342-343.

Transcribed by Lars Bruzelius

Sjöhistoriska Samfundet | The Maritime History Virtual Archives.

© Copyright 1997 Lars Bruzelius.