MAST (continued)

When the vessel is launched, before the places of the masts are determined, extend a rope A B, fig. 5. plate VI. from the head to the stern. To the extremities A and B attach two other ropes AD, BC, and apply to the other ends of these ropes two mechanical powers, to draw the ship according to the direction B C, parallel to itself. The whole being thus disposed, let a moveable tube Z, fixed upon the rope A B, have another rope Z R attached to it, whose other end communicates with a mechanical power R, equal to the two powers D and C. This last being applied to the same vessel, in such manner as to take off the effects of the two others by sliding upon the rope A B, so as to discover some point Z, by the parallelism of the ropes A D BC seebly extended with the rope Z R; the line Z R will be the axis of the equilibrium of the water's resistance, and by consequence the main-mast should be planted in the point Z.

Plate VI

The figures E, E, E, are three windlasses on the shore, by which this experiment is applied.

With regard to the situation of the other masts, it is necessary, in the same manner, to discover two points; so that the direction of the two mechanical powers operating, will be parallel to the axis of resistance R Z already found.

The exact heighth of the masts, in proportion to the form and size of the ship, remains yet a problem to be determined. The more the masts are elevated above the center of gravity, the greater will be the surface of sail, which they are enabled to present to the wind'; so far an additional heighth seems to be advantageous. But this advantage is diminished by the circular movement of the mast, which operates to make the vessel loop to its effort; and this inclination is increased, in proportion to the additional heighth of the mall; an inconvenience which it is necessary to guard against. Thus what is gained upon one hand is lost upon the other. To reconcile these differences, it is certain, that the heighth of the mast ought to be determined by the inclination of the vessel, and that the point of her greatest inclination should be the term of this heighth, above the center of gravity. See the article TRIM.

With regard to the general practice of determining the heighth of the masts, according to the different rates of the ships in the royal navy, the reader is referred to the article SAIL.

In order to secure the masts, and counterbalance the strain they receive from the effort of the sails impressed by the wind, and the agitation of the ship at sea, they are sustained by several strong ropes, extended from their upper-ends to the outside of the vessel, called shrouds, see fig. 5. plate VI. They are further supported by other ropes, stretched from their heads towards the fore-part of the vessel. See RIGGING.

Reference Works