Close Hauled or "Beating"

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

A boat can be 'worked to windward', to arrive at an upwind destination, by sailing close-hauled with the wind coming from one side, then tacking (turning the boat through the eye of the wind) and sailing with the wind coming from the other side. By this method of zig-zagging into the wind, known as beating, it is possible to reach any upwind destination. A yacht beating to a mark directly upwind one mile away will cover a distance through the water of at least 1.4 miles, if it can tack through an angle of 90 degrees including leeway. An old adage describes beating as sailing for twice the distance at half the speed and three times the discomfort.
An estimate of the correct tacking distance can be obtained (and thereby the time taken to travel it at various boat speeds) by using Pythagoras' theorem with equal tacks (assume a value of 1). This also assumes a tacking angle of 90°. The straight line distance is the hypotenuse value of √2
When beating to windward one tack may be more favorable than the other - more in the desired direction. The best strategy is to stay on the favorable tack as much as possible. If the wind shifts in the sailor's favor, called a lift, so much the better, then this tack is even more favorable. But if it shifts against the sailor's, called a header, then the opposite tack may become the more favorable course. So when the destination is directly into the wind the best strategy is given by the racing adage "tack on a header." This is true because a header on one tack is a lift on the other.
How closely a boat can sail into the wind depends on the boat's design, sail shape and trim, the sea state, and the wind speed.
Typical minimum pointing angles to the true wind are as follows. Actual course over the ground will be worse due to leeway.

• about 35° for modern racing yachts which have been optimized for upwind performance (like America's Cup yachts)
• about 40 to 45° for modern cruiser-racer yachts (fast cruising yachts)
• about 50 to 60° for cruisers and workboats with inefficient keels, inefficient hull shapes, or low draught, when compared to craft designed for sailing performance, and for boats carrying two or more masts (since the forward sails adversely affect the windward ability of sails further aft when sailing upwind)
• close to 90° for square riggers and similar vessels due to the sail shape which is very ineffective when sailing upwind

Close hauled or "beating"

Sailing close-hauled under a large amount of sail, and heeling a great deal, can induce weather helm, or a tendency for the boat to turn into the wind. This requires pulling the tiller to windward (i.e. 'to weather'), or turning the wheel leeward, in order to counteract the effect and maintain the required course. The lee side of the hull is more under water than the weather side and the resulting shape of the submerged parts of the hull usually creates a force that pushes the bow to weather. Driving both the asymmetric heeling hull form and the angled rudder through the water produces drag that slows the boat down. If weather helm builds further, it can limit the ability of the helmsperson to steer the boat, which can be turned towards but not effectively away from the wind. At more extreme angles of heel, the boat will spontaneously 'round up' into the wind during gusts, i.e. it will turn into the wind regardless of any corrective action taken on the helm.
Any action that reduces the angle of heel of a boat that is reaching or beating to windward will help reduce excessive weather helm. Racing sailors use their body weight to bring the boat to a more upright position, but are not allowed to use "movable ballast" during a race.  Reducing or reefing the total sail area will have the same effect and many boats will sail faster with less sail in a stiff breeze due to the reduction in underwater drag. Easing the sheets on aft-most sails, such as the mainsail in a sloop or cutter can have an immediate effect, especially to help with manoeuvering. Moving or increasing sail area forward can also help, for example by raising the jib (and maybe lowering the staysail) on a cutter.