Although many cruising sailors won’t be as inclined to tweak sail controls as readily as racing sailors, the fact remains that an understanding of what the basic controls are, what they do and being prepared to change things once in a while can have a significant bearing on sail shape and therefore the manageability of both the sail and the boat.

The four primary controls are halyard tension, sheet lead position, sheet tension and backstay tension.

Increasing halyard tension pulls the position of maximum draft in the sail forwards. This, in turn, flattens the aft sections of the sail, thus reducing heel and backwinding.

More halyard tension is needed as the breeze increases, although care should be taken not to over-tension the luff, as indicated by a ‘gutter’ that runs parallel with the luff.

Headsail trim techniques

The sheet lead position should be set so that it roughly bisects the clew, applying equal tension to the leech and foot as the sail is sheeted.

If you imagine a line extending up through the sail as a continuation of the sheet, it should meet the luff of the sail in the middle.

As the breeze increases and the sail is sheeted harder, the genoa car will need to come aft slightly.

Backstay tension directly affects the amount of headstay sag (to a greater or lesser degree, depending on the rig characteristics of a particular boat).

More sag adds depth, creating a more powerful sail. Once again, as the breeze increases, you should pull the backstay on harder to help prevent the headsail from becoming excessively deep.

If your boat is becoming a bit of a handful, don’t be afraid to try these little adjustments.

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