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A sail-plan is a formal set of drawings, usually prepared by a marine 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:

A light air sail plan. Over most of the Earth, most of the time, the wind force is Force 1 or less. Thus an effective sail plan should include a set of huge, lightweight sails that will keep the ship underway in light breezes.

A working sail plan. This is the set of sails that are changed rapidly in variable conditions. They are much stronger than the light air sails, but still lightweight. An economical sail in this set will include several sets of furling ties. so a sail can be flown in varying amounts of wind.

A storm sail plan. This is the set of very small, very rugged sails flown in a gale, to keep the vessel under way and in control.

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.

Sailing frigate and its rigging.


In English, courtesy of the British Admiralty, all sail-plans call a sail by the same name, no matter what their sail-plan. Once a sail is named, its ropes have standard names according to their use. So once a sailor learns the standard names for the sails, he knows the terms for all the parts on any sail-plan.

A sail plan is made by combining just a few basic types of sails:

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

Ropes are almost as important:

Ropes were classically made of manila, cotton, hemp or jute. They are now made of stainless steel (301), galvanized steel, polyester (Dacron), polyamides (Nylon), and sometimes crystallized hydrocarbons (Kevlar and Spectra™).

The standard terminology assumes three masts, from front to back, the fore-mast, main-mast and mizzen-mast. On ships with less than three masts, the tallest is the main-mast. Ships with more masts number them. Some barks (see below) have had as many as twelve masts.

The heights of the sails are named roughly after the bravery of the man needed to work on each, except the skysail, which existed only on American clipper ships.

From bottom to top, the sails of each mast are named by the mast and position on the mast, e.g. for the main-mast, from lowest to highest: main-sail, lower-main-top-sail, upper-main-top-sail, main-gallant, main-royal, and main-skysail. The sails for the foremast are called fore-sail, lower-fore-top-sail, etc. For the mizzenmast, mizzen-sail, etc.

On many warships, sails above the lower-top-sails were mounted on temporary masts ("top-masts" or "top-gallant-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 out on the ends of the yardarms. These were called as a regular sail, with the addition of "studding." For example, the lower-main-top-studding-sail.

The staysails between the masts are named by the highest point (the danger) to which a sailor must climb to furl or unfurl the sail. The name is from the sail immediately below the highest attachment point of the stay holding up the staysail. Thus, the mizzen-top-gallant-stay-sail can be found dangling from the stay leading from above the mizzen (third) mast's top-gallant (fifth) sail to some place (usually two sails down) on the second (main) mast.

The jibs, the staysails between the first mast and the bowsprit, were named like staysails, except the middle one was called a jib, and the top one was called a flying jib.

For inscrutable reasons, the stays below a bowsprit are martingales, and those above it bracing the bowsprit are bobstays. The martingales are often the strongest stays on a ship, and often constructed of chain.

The stays on a ship roughly form hoops of tension holding the masts up against the wind. Many ships have been "tuned" (or "raked") 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. This was a common emergency procedure on sailing warships.

In a bark or barkentine, each mast only has one gaff-sail, and this is always the lowest sail on the back of the mast. Barks are famous for being easy to sail.

Almost every type of tall ship had a gaff-sail on the mizzenmast, and called it the spanker.

A ship would fly its ensign and anchor light off a drop line from the spanker's gaff.

Some standard sail plans are:

See also