Two sorts of topsails can be set on a topmast—a yard topsail, by which a large area of canvas is obtained, and a jib-headed topsail. In a good-sized yacht it is well to have both. The jib-header can be used in strong winds. When out at sea in really bad weather, it is often of great advantage to set the jib-header over a reefed mainsail, for the wind still fills it, and the steerage way is preserved while the reefed mainsail is becalmed in the trough of the sea. By means of a jackyard, which extends the foot of the sail beyond the end of the main gaff, the area of either a jib-header or a yard topsail can be increased.
When a cutter is running before the wind, a jib-headed sail, called a spinnaker, can be set on the opposite side to the mainsail. (See [Fig. 38].)
The spinnaker boom is fitted to the fore-side of the mast by a gooseneck, and if the sail is intended for cruising purposes only, the boom should, when topped up along the mast with its topping-lift, be able to pass under the forestay.
The spinnaker halyard passes through a block on the mast, and the clew of the sail is hauled out to the end of the boom by an outhaul, while the tack can be made fast to a cleat on deck.
Fig. 38.
In order to prevent the spinnaker boom from swinging fore or aft, it is stayed or guyed with a fore guy leading to the stem, and an after guy leading to the stern. These guys also serve to trim the boom to the required angle.
Most of the blocks now used on yachts have iron strops to them; but it is still necessary that the amateur sailor should know how to strop a block.
If it be a tail block for which the strop is required, this can be done by making an eye splice in the piece of rope that is to serve as the tail. The common form of strop is a rope grommet coated with canvas.