By Terry Flynn

trim for control 16 ADVICE FROM THE PROS: Head Sail Trim Tips

Head Sails come in many shapes and sizes, from overlapping genoas to smaller efficient 100% jibs. Though headsails differ, some basic principles will help you understand how to trim your sails for maximum efficiency.

Headsail: Primary Controls

Halyard Tension.  The key to proper tension is looking at the luff.  You want to apply enough to keep the horizontal wrinkles from appearing but not enough to have a ridge behind the headstay.  The halyard should be adjusted as the wind speeds go up and down.  More for heavier wind and less for lighter winds.  Try adjusting it while watching the sail. You should be able to see the draft move forward with more halyard tension.

Lead Car Position.  This is one of the most important settings on the boat.  This controls the depth of the genoa or jib from top to bottom.  If the lead is too far forward, the top is closed up and the foot too round.  If the lead is too far aft, the foot gets round and the leach opens up and depowers the top making the sail less powerful.  A good rule of thumb is, when trimming the sail with the correct lead position, the foot of the jib will touch the upper shroud at the same time as the sail touches the spreader.  When looking at the sail, it should look like the middle of the sail is parallel to the upper shroud.  You will also notice that, when the lead is correct, most of the telltales will be break evenly from top to bottom

Genoa Jib Sheet. Now that you have the proper lead placement you need to know how much you can trim the sail.  This is usually judged by how close to the spreader you can get or how far inside the side of the boat you can go.  Today’s race boats are designed to carry the genoas almost touching the spreaders.  Cruising boats should keep the sail from 5” to 10” away from the spreaders.  Trimming it in too far will just stall the boat out and slow the boat down.

Back Stay.  For most boats this is a fixed turnbuckle.  If you have a purchase system or hydraulic adjuster, you have an advantage.  Like the halyard tension, this will be adjusted as the wind goes up and down.  Ideally, on the average cruising boat, you will see 6” to 12” of sag from top to bottom.  As you add backstay tension your genoa will get flatter so there will be less heeling.  In the lighter winds, the more sag will make the genoa fuller with more power.

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