Trim the Sail on Your Sailboat

What You'll Need
Jib sheets
Winch handle

Trimming the sails on your sailboat is the process of positioning the angle of the sails in just the right manner so that they catch the wind most efficiently. When trimmed correctly, the wind will flow evenly over both sides of the sails at the leading edge–that closest to the wind. An incorrectly trimmed sail is said to be luffing. A luffing sail is easy to spot, for it flaps in the wind and is serving no purpose but to slow down your boat. Trimming is the process of trial and error that puts your sails in the position of maximum efficiency and stops them from luffing. You can immediately tell when the luffing stops for the sail fills with air and tightens up.

Step 1: Look to the Telltales

Telltales are small pieces of acrylic fabric attached to each sail. You find them on both sides of the sail. On a jib sail, they are about six inches from the luff edge of the sail, while they are closer to the leech on a mainsail. They indicate not only the direction of the wind but how well the wind is moving over the sails. You will also find telltales on top of the mast and on the shrouds, although those on sails will help you trim them.

Step 2: What the Telltales Tell

A properly trimmed sail will be indicative by the telltales. On both sides of the sail they should be blown by the wind evenly. An improperly trimmed sail may have a telltale on one side positioned correctly, but on the other side it is flapping about. This means the wind is not moving correctly over both sides of the sail. In order to power the boat, the wind must be efficiently used.

Step 3: Sailing Too Close to the Wind

If you are sailing too close to the wind, the windward telltale–on the side closest to the wind–will flap and flutter. This means the sail is under-trimmed. Either change course and turn slightly from the wind or pull in or trim the sheet to make the sail tauter. If you are trimming the jib sail, trim the leeward sheet. On the mainsail there is only one sheet to trim.

Step 4: Sailing Too Far Away from the Wind

On the other hand, if your boat is not close enough to the wind, the leeward telltale will flutter. In this case, the sail is too tightly trimmed and must be eased, or you should change course and turn towards the wind slightly. To ease the jib sail, let out a little of the line so that the sail opens up some. Release as much as is necessary to get the telltales pointing directly aft on both sides of the sail.  

Trimming the sails on your sailboat takes practice. It is not only a matter of knowing how to do it, you also must constantly be aware of the wind direction. The wind is always changing. This means that in order to keep your boat moving efficiently, you must trim and/or ease the sails in response. Either that or you must change course. With experience, the motions will become second nature and you will gain an intuitive understanding of the wind.