The Winch. — This is also a machine on the same principle as the two we have described; but instead of being hove round with handspikes, it is turned round by crank-handles. The winch is much smaller than the windlass or capstan, and only intended for light purposes, such as warping the vessel from one place to another in harbour, or hoisting in or out light goods, or setting the sails, &c. There are two kinds, the single and double winch, the latter being contrived so that the power can be increased beyond that of a single winch. Both kinds are simple in their construction.
The single-winch consists of a horizontal iron spindle, crossing the middle of the deck, supported at a certain height above the same by two stout pieces of wood, called the winch-bitts. The spindle revolves in two bushes fixed on the after-side of the bitts, which are commonly placed about 6 to 6½ feet apart, as the other conveniences on deck may require. On the ends of the spindle, which projects beyond the outside of the bitts about 14 to 18 inches, are fixed circular pieces of hard wood for taking the rope round. These pieces are commonly called the winch-ends, or drums. On the end of which, next the bitt, is fixed a ratchet-wheel; and a pawl, for working in the same, is attached to the bitt. On the extreme ends of the spindle are fixed the crank-handles, at which the men exert their force in turning it round.
The double-winch has two spindles, the one above the other, with two ends or drums. There is a small pinion fixed on the upper spindle, which slides in the bushes, and is accordingly thrown in or out of the gear of a large wheel fixed on the lower spindle. The handles are fixed on the upper spindle, which answers best to be about 3½ feet above the deck. Although the winch has been long used for land purposes, it is only lately that it has been generally fitted up in vesels. It is extremely useful in small brigs, as the capstan frequently occupies too much room on deck; in large smacks, also, the double-winch is of great utility for heaving up their heavy sails, and taking in and out the heavy articles of the cargo.
Figs. 10 and 11, Plate XI. is a drawing of the double winch calculated for a smack of about 200 tons. The winch commonly stands between the main hatch and mast in smacks, and before the main-mast in brigs and schooners, — (see Fig. 10, where A A is the deck, B B the winch-bitts, C the upper spindle, D the lower spindle.) But a bare inspection of the figure supersedes the necessity of any farther description.
Between the pinion on the upper spindle, and the wheel on the lower one, is placed an intermediate one, sliding in an arbour. This is introduced merely to keep the two spindles separate, to allow the heel of the bowsprit to run between them. Sometimes, hwoever, and which is found equally convenient, the heel of the bowsprit runs in over the upper spindle; and the construction, in this case, is shewn by Fig. 11. The double-winch (Fig. 10) is thrown in or out of gear by sliding the intermediate wheel on the arbour, and (Fig. 11) by sliding the upper spindle in the bushes, the lower spindle being at the same time secured with pawls.
The power of the single-winch is commonly about 4 to 1. that is, the drum or winch end is 1-4th of the diameter of the circle described by a revolution of the handle, and is estimated thus:— As the semidiameter of the drum or winch-end, adding the thickness of the rope, is to the length of the crank of the handle, so is the power applied to the weight which may be raised; and when a rope is taken to the double-winch, or lower barrel, the power is increased commonly as 12 to 1, that is, until 1 lb. upon the handle balance 12 lbs. suspended from the circumference of the lower barrel.
|Thus, if the sweep of the handle is||16 inches,||}||it produces a power of 4 to 1.|
|The radius of the pinion||4 inches,|
|Then, let the wheel on the lower spindle, and on which the pinion acts, be||27 inches,||}||this will produce a power of 3 to 1;|
|And the barrel of the lower winch||9 inches,|
and hence a power of 4 to 1, working upon another of 3 to 1, produces 4×3=12, a power of 12 to 1; and deducting 1-6th of the whole for friction, we shall still have an efficient power of 10 to 1.
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 314-315.
Transcribed by Lars Bruzelius.
Sjöhistoriska Samfundet | The Maritime History Virtual Archives | Shipbuilding | Search.
Copyright © 2002 Lars Bruzelius.