Sail Trim
From the Miami Valley MYC Newsletter
By way of the Eagle Dropping, April 1997
The object of trimming the sails is to give the boat a slight weather helm during steady winds. With the proper amount of weather helm the boat will head up in puffs and fall off in lulls.
1.Adjust the backstay to suit wind conditions based on jibstay sag.
2. Adjust the mainsail.
a. Set luff tension with cunningham to remove wrinkles from mainsail luff.
b. Set mainsail fullness with outhaul.
c. Set mainsheet so boom is about "" off centerline.
d. Adjust vang to allow main leech to be parallel with boat's centerline about half way up the sail (stand in back of boat and line up the battens so you can see the leeward side of the bottom batten, the windward side of the top batten and neither side of the middle battens).
e. Re-adjust both main sheet and vang until the leech looks correct.
3. Adjust the jib.
a. Set jib luff tension with downhaul to remove wrinkles from luff.
b. Set jib fullness with outhaul.
c. Set jib sheet so that you can see jib clew from behind the main when standing behind the boat.
d. Adjust topping lift so that jib twist is the same as the main twist.
e. Re-adjust both the jib sheet and the lift until the leech looks correct.
4. Sail the boat to evaluate the effect of true wind on your trim.
a. Bear off the wind to check that the jib luffs slightly just before the mainsail does.
b. Check to see that the boat has slight weather helm in steady winds.
c. Sail the boat close-hauled away from you to check the twist of both the mainsail and the jib.
Remove boat from the water and re-adjust as required using steps 2 to 4.
Heavy Air Sail Trim Notes
Note: You may have to move the mast forward to reduce weather helm.
1. Backstay.
a. Tighten backstay tension until you see diagonal creases from clew to midpoint of sail and then reduce the tension slightly until creases just disappear.
2. Main.
a. Tighten cunningham and outhaul to the point where wrinkles just start to appear to flatten main.
b. Set mainsheet to more than 1" off centerline.
c. Adjust vang to allow for more twist in the upper portion of the mainsail.
3. Jib.
a. Tighten downhaul and outhaul to the point where wrinkles just start to appear in order to flatten jib.
b. Jib slot doesn't have to be as large as with normal sailing, tighten slot until jib back winds the main in puffs but not the lulls.
c. Adjust topping lift to match jib twist with the main twist.
d. Note that if conditions are choppy, jib should be set fuller to increase power.
Light Air Sail Trim Notes
1. Set sail adjustments light.
2. Set mainsheet to more than 1" off centerline.
3. Increase sail twist.
4. Increase slot between main and jib.
5. Don't pinch the boat when sailing to windward.
Remember, when in doubt, let them out!
By way of the Eagle Dropping, April 1997
The object of trimming the sails is to give the boat a slight weather helm during steady winds. With the proper amount of weather helm the boat will head up in puffs and fall off in lulls.
1.Adjust the backstay to suit wind conditions based on jibstay sag.
2. Adjust the mainsail.
a. Set luff tension with cunningham to remove wrinkles from mainsail luff.
b. Set mainsail fullness with outhaul.
c. Set mainsheet so boom is about "" off centerline.
d. Adjust vang to allow main leech to be parallel with boat's centerline about half way up the sail (stand in back of boat and line up the battens so you can see the leeward side of the bottom batten, the windward side of the top batten and neither side of the middle battens).
e. Re-adjust both main sheet and vang until the leech looks correct.
3. Adjust the jib.
a. Set jib luff tension with downhaul to remove wrinkles from luff.
b. Set jib fullness with outhaul.
c. Set jib sheet so that you can see jib clew from behind the main when standing behind the boat.
d. Adjust topping lift so that jib twist is the same as the main twist.
e. Re-adjust both the jib sheet and the lift until the leech looks correct.
4. Sail the boat to evaluate the effect of true wind on your trim.
a. Bear off the wind to check that the jib luffs slightly just before the mainsail does.
b. Check to see that the boat has slight weather helm in steady winds.
c. Sail the boat close-hauled away from you to check the twist of both the mainsail and the jib.
Remove boat from the water and re-adjust as required using steps 2 to 4.
Heavy Air Sail Trim Notes
Note: You may have to move the mast forward to reduce weather helm.
1. Backstay.
a. Tighten backstay tension until you see diagonal creases from clew to midpoint of sail and then reduce the tension slightly until creases just disappear.
2. Main.
a. Tighten cunningham and outhaul to the point where wrinkles just start to appear to flatten main.
b. Set mainsheet to more than 1" off centerline.
c. Adjust vang to allow for more twist in the upper portion of the mainsail.
3. Jib.
a. Tighten downhaul and outhaul to the point where wrinkles just start to appear in order to flatten jib.
b. Jib slot doesn't have to be as large as with normal sailing, tighten slot until jib back winds the main in puffs but not the lulls.
c. Adjust topping lift to match jib twist with the main twist.
d. Note that if conditions are choppy, jib should be set fuller to increase power.
Light Air Sail Trim Notes
1. Set sail adjustments light.
2. Set mainsheet to more than 1" off centerline.
3. Increase sail twist.
4. Increase slot between main and jib.
5. Don't pinch the boat when sailing to windward.
Remember, when in doubt, let them out!