Sail-plan

A sail-plan is a set of drawings, usually prepared by a naval architect. It shows the various combinations of sail proposed for a sailing ship.

The combinations shown in a sail-plan almost always include three configurations:

In all sail plans, the architect attempts to balance the force of the sails against the drag of the underwater keel in such a way that the vessel naturally points into the wind. In this way, if control is lost, the vessel will avoid broaching (turning edge-to-the wind), and being beaten by breaking waves. Broaching always causes uncomfortable motion, and in a storm, the breaking waves can destroy a lightly built boat. The architect also tries to balance the wind force on each sail plan against a range of loads and ballast. The calculation assures that the sail will not knock the vessel sideways with its mast in the water, a capsize and possible sinking.

Contents

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Terminology

Types of sail

Order

The standard terminology assumes three masts, from front to back, the fore-mast, main-mast and mizzen-mast. On ships with fewer than three masts, the tallest is the main-mast. Ships with more masts number them.

From bottom to top, the sails of each mast are named by the mast and position on the mast, e.g. for the mainmast, from lowest to highest: main course, main topsail, main topgallant ("t'gallant"), main royal, main skysail, and main moonraker. Since the early twentieth century, the topsails and topgallants are often split into a lower and an upper sail to allow them to be more easily handled.

On many warships, sails above the fighting top (a platform just above the lowest sail) were mounted on separate masts ("topmasts" or "topgallant masts") held in wooden sockets called "tabernacles". These masts and their stays could be rigged or struck as the weather and tactical situation demanded.

In light breezes, the working square sails would be supplemented by studding sails ("stuns'l") out on the ends of the yardarms. These were called as a regular sail, with the addition of "studding". For example, the main top studding sail.

The staysails between the masts are named from the sail immediately below the highest attachment point of the stay holding up the staysail. Thus, the mizzen topgallant staysail can be found dangling from the stay leading from above the mizzen (third) mast's topgallant sail to some place (usually two sails down) on the second (main) mast.

The jibs, staysails between the first mast and the bowsprit were named (from inner to outer most) fore topmast staysail (or foretop stay), inner jib, outer jib and flying jib. All of the jib's stays meet the foremast just above the fore topgallant. Unusually, a fore royal staysail may also be set.

Material

Sails were classically made of hemp or cotton. They are now made from polyesters (Dacron and PET film), sometimes reinforced with crystalline hydrocarbons (Kevlar and Spectra). Some large, lightweight sails are made of polyamides (nylon).

Ropes

Ropes were classically made of manila, cotton, hemp, or jute; papyrus (in ancient Egypt) and coir have also been seen. They are now made of stainless steel (301), galvanized steel, polyester (Dacron), polyamides (nylon), and sometimes crystallized hydrocarbons (Kevlar and Spectra).

Rigging

Sprit and stays

The stays on a ship roughly form hoops of tension holding the masts up against the wind. Many ships have been "tuned" by tightening the rigging in one area, and loosening it in others. The tuning can create most of the stress on the stays in some ships.

Types of ships

Sailboat types may be distinguished by:

Sail-plan measurements

Every sail-plan has maximum dimensions.[1][2] These maxima are for the largest sail possible and they are defined by a letter abbreviation.

See also

Notes

Further reading

External links