POINTS OF SAIL

The points of sail are the most important parts of sail theory to remember. The wind, irons, or no go zone, is about 45° either side of the true wind, for a racing hull and sail plan optimized for upwind work. More commonly and on cruising sailplans, the best angle achievable upwind is 50° to 55° to the true wind. A boat cannot sail directly into the wind; attempting to do so is called luffing. There are 5 main points of sail. In order from the edge of the no go zone to directly downwind they are:

• close haul (22° to the apparent wind)
• close reach (half way between close hauled and a beam reach)
• beam reach (90° to the apparent wind)
• broad reach (22.5° away from directly downwind sailing)
• running (directly downwind)

The sail trim (and, on smaller boats, centre board/dagger board position) on a boat is relative to the point of sail one is on: on a beam reach sails are half way out, on a run sails are all the way out, and close hauled sails are pulled in very tightly. A large proportion of the skill of sailing is in trimming the sails correctly for direction and strength of the wind.

BEATING

Using a series of close-hauled legs to beat a course upwind.

A basic rule of sailing is that it is not possible to sail directly into the wind—at least not for long. Generally speaking, a modern boat can sail 45 degrees off the wind. When a boat is sailing this close to the wind, it is close-hauled or beating (beating to weather).

Because a boat cannot sail directly into the wind, but the destination is often upwind, one can only get there by sailing close-hauled with the wind coming from the port side (the boat is on port tack), then tacking (turning the boat through the eye of the wind) and sailing with the wind coming from the starboard side (the boat is on starboard tack). By this method, it is possible to reach that destination directly upwind. For a yacht beating upwind to a mark at a distance upwind of one mile, it will cover a distance through the water of over 1.42 miles, if it can tack through an angle of 90 degrees. An old adage describes beating as sailing for twice the distance at half the speed and three times the discomfort.

How closely a boat can sail into the wind depends on the boat's design, sail trim, the sea state, and the wind speed, since what the boat "sees" is the apparent wind, the vector sum of the actual wind and the negation of the boat's own velocity. The apparent wind speed is what the anemometer on top of the mast shows. The apparent wind angle while sailing close hauled will be less than the true wind angle. A good, modern sloop can sail within 25 degrees of the apparent wind. An America's Cup racing sloop can sail within 16 degrees—under ideal conditions. Those figures might translate into 45 degrees and 36 degrees relative to the actual wind, depending on boat speed.

REACHING

When the boat is traveling approximately perpendicular to the wind, this is called reaching. A 'beam' reach is with the wind precisely at right angles to the boat, while a 'close' reach is halfway between beating and a beam reach, and a 'broad' reach is a little bit away from the wind.

For most modern sailboats, that is boats with triangular sails, reaching is the fastest way to travel. The direction of the wind is ideal for reaching because it will maximize the lift generated on the sails in the forward direction of the boat, giving the best boat speed. Also when reaching, the boat can be steered exactly in the direction that is most desirable, and the sails can be trimmed for that direction.

Reaching however may put the boat on a parallel course with the waves. When the waves are steep, it may be necessary to sail closer to the wind to avoid waves directly on the beam.

RUNNING

Sailing the boat within roughly 30 degrees either side of dead downwind is called a run. This is the easiest point of sail in terms of comfort, unless in a small dinghy (as cramp can set in), but it can also be the most dangerous. (deathrolls leading to turtles are very common in high winds). When sailing upwind, it's easy to stop the boat by heading into the wind; a sailor has no such easy out when running. Severe rolling is more likely as there is less rolling resistance provided by the sails, which are eased out. And loss of attention by the helmsman could lead the boat to gybe accidentally, causing injury to the boat or crew. (A preventer can be rigged to prevent damage from an accidental gybe.) Alternately, if there is a sudden increase in wind strength, the boat can round up very suddenly and heel excessively, often leading to a capsize in smaller boats. This is called broaching.