The big Ease 

It's been our experience that sailors are often a little at a loss at how to deal with sail trim in that netherland between the beat and the spinnaker set. 

The basics are well known: ease the jib until it luffs then pull it back in a little; ease the outhaul, the cunningham and the backstay; pull the vang to keep the boom down; and ease the mainsheet until the main begins to luff, then trim it back a little. 

These are all good ideas, but there are some more little tweaks that can add greatly to your performance on a jib reach.

Jib leads 

Move your jib lead forward. As you ease your jib sheet the top of the sail tends to twist to leeward quickly. Sails need to be twisted more on a reach than on a beat. However, this twist increases too fast if we leave bottom of the sail gets fuller as the clew moves toward the headstay. But the angle of the foot of the sail to the centerline changes very little while the apparent wind is moving aft. This makes a very deep section at a high angle of attack which is a great candidate for high drag and lots of flow separation. By moving the lead outboard or barberhauling to the rail, we can flatten the bottom of the sail and reduce the angle of attack to get a more efficient air foil. Once again, this new lead position will need to be closer to the headstay than the upwind sheet position, because the reaching sail needs to be fuller than the upwind sail without twisting off too much. In very broad jib reaches, the best trim point may be off the boat. Using a spinnaker or whisker pole to leeward may help create that ideal sheeting point outside the deck, just as the main boom does for the reaching mainsail.

Once you understand the principles, the best way to learn what works on a jib reach on your boat is to experiment. Don't forget to watch those telltales. the lead in the same spot and just ease. To keep the twist under control, you must keep the clew from rising excessively as the sheet is eased. By moving the lead forward, we keep the clew height under control. 

Move the jib lead outboard. As the jib sheet gets eased, thebottom of the sail gets fuller as the clew moves toward the headstay. But the angle of the foot of the sail to the centerline changes very little while the apparent wind is moving aft. This makes a very deep section at a high angle of attack which is a great candidate for high drag and lots of flow separation. By moving the lead outboard or barberhauling to the rail, we can flatten the bottom of the sail and reduce the angle of attack to get a more efficient air foil. Once again, this new lead position will need to be closer to the headstay than the upwind sheet position, because the reaching sail needs to be fuller than the upwind sail without twisting off too much. In very broad jib reaches, the best trim point may be off the boat. Using a spinnaker or whisker pole to leeward may help create that ideal sheeting point outside the deck, just as the main boom does for the reaching mainsail.

Once you understand the principles, the best way to learn what works on a jib reach on your boat is to experiment. Don't forget to watch those telltales.

Maine Sailing Partners
www.mesailing.com
1-888-788-SAIL