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Friday, November 29, 2013
Level 14: Advanced Sail-trim on all courses
Headsail Trim:
1. Lead position. This means setting the lead angle and fore-aft position of the sheet lead. The fore-aft lead is positioned by drawing an imaginary line from midluff through the clew to the deck. Midluff is the point at the luff directly ahead of the second set of telltales. Fine-tune the lead position by slowly rounding into the wind and watching the telltales. All the weather telltales should flip up at once, indicating that the top and bottom of the sail are trimmed equally. If the top luffs first, move the lead forward; if the bottom luffs first, move the lead back. It is best to err on the side of too far back. This increases twist and gives the sail a larger "sweet spot".
2. Trim. Trim the sail close to, but not touching, the spreaders. The optimum trim may put the leech slightly in or out from this setting, with some variation according to sea and wind conditions.
3. Halyard Tension. Use halyard tension to pull the draft forward, but do not tension the halyard so much that you get a vertical wrinkle behind the headstay. Never overtension the halyard, watch the halyard marks.
4. Adjustments. In flat water and medium air, trim harder and move the lead angle in-board to flatten the sail and narrow the angle of attack. Tighten the backstay to reduce headstay sag and flatten the entry. In waves, ease the sheet, move the lead outboard, and sail lower angles to maintain speed. Ease the halyard slightly and ease the backstay if the rig doesn't move around too much. For heavy air, move the lead outboard, but keep the sheet and halyard in hard to keep the sail flat. Move the lead aft to free the upper leech and flatten the head--tolerate a slightly earlier luff in the top of the sail if necessary. For very light winds, move the lead outboard, ease the sheet and move the lead forward enough to maintain an even break along the luff. Use light backstay and halyard tension, and sail with the leeward telltale on the verge of stalling.
5. Effect on the mainsail. If the main is fluttering or backwinding excessively and all other setting are correct, move the headsail lead outboard or change to a flatter or smaller headsail.
6. Using the correct sail. The following table provides a guide for selecting the correct sail.
7. Record the settings. When the boat is sailing fast, record the settings on a Genoa Trim Card.
Mainsail Upwind Trim:
1. Sheet tension and Traveler Position. Tighten the sheet and set the traveler car position so that the boom is roughly on the centerline of the boat. If the boat is getting overpowered (excessive weather helm) let the boom fall to leeward until back under control.
2. Trimming the upper batten. Trim the mainsheet until the top batten is parallel to the boom. Assuming that the main has the correct vertical curvature, draft distribution and sectional shape, this will bring the elements of twist, camber, angle of attack and power to the correct settings. To determine the angle between the top batten and boom, crouch under the boom and sight upward, lining up the reference points.
3. Main telltales. When trimmed correctly, the telltale on the top batten should be streaming aft most of the time and stalling (curling behind the main) once in a while. In ideal conditions--flat water and medium air-- trim the mainsheet harder so that the top telltale is stalled most of the time and the top batten hooks slightly to windward.
4. Leech tension. This is used to control helm and pointing. The tighter the leech the more helm and the higher the boat will point. Remember, however, that you must have speed before shifting into the pointing mode.
5. Traveler position. Use the traveler as the accelerator. When you need more speed, drop the traveler to leeward and foot off a few degrees. Trade speed for pointing by pulling the traveler to windward and pointing higher.
6. Position of maximum draft. The maximum draft should be positioned roughly 48-50% oft from the luff. Move draft forward when power is needed for acceleration or punching through waves. Use the cunningham rope to control the draft position. Pull it just tight enough to remove most of the wrinkles along the luff. New sails may be fastest with a few wrinkles showing.
7. Flatten in heavy air and smooth water. Flatten the main by increasing the amount of mast bend. This is done by increasing backstay tension, which also reduces headstay sag and is desirable. Watch for "overbend wrinkles" that extend from the lower-middle part of the mast to the clew. This indicates that the sail has reached maximum flatness and additional adjustment is overstressing the rig.
8. Fuller main for light air or waves. Increase the fullness of the main for light air or waves by reducing the backstay tension. Be careful not to allow too much headstay sag.
9. Target depth and draft positions.
These are general targets only and need to vary depending on the sail and boat.
Mainsail Downwind trim:
1. Trim for "backwind". Ease the sheet until you just start to see backwind or luffing along the luff edge of the sail. Play the main sheet to keep the sail on the edge of luffing.
2. Outhaul and Cunningham. Ease the outhaul and cunningham to make the sail fuller. The halyard may also need to be eased if vertical wrinkles along the luff are seen.
3. Trimming the upper batten. Adjust the mainsheet and vang so that the upper batten is parallel to the boom. On reaches set the leech so the upper-batten telltale streams aft most of the time. This minimizes backwind from the lower leech of the genoa or spinnaker.
4. Vang. Be careful not to overdo the vang in light and medium air. In these conditions the weight of the boom is enough to provide the leech tension. On heavy-air runs, use lots of vang. This reduces the upper leech twist which makes the boat want to roll. To damped rolling, sheet in.
5. Over powered reach. Leave the outhaul tight. Ease the vang enough to keep the end of boom out of the water when rolling. Dump the sheet when the heel becomes too great. If the boom end drags in the water a lot, reef the main.
6. Light air. Have a crew member hold the boom out, especially if heeling to windward. Make sure the pressure is out and not down.
7. Trimming order. The headsail, genoa or spinnaker is trimmed first. The headsail trimmer must tell the main-trimmer when making a change.
Shifting Gears:
When working to windward, and especially at the start, the sails can be trimmed to maximize; 1) Acceleration, 2) Speed, 3) Pointing and 4) Low Leeway. The following are general guidelines for trimming to each 'gear'. The trim parameters that are adjusted on the main are; Sheeting angle (boom position), Mast bend (backstay tension & checkstay tension), Draft (outhaul), Draft position (cunningham), and Twist (mainsheet). The trim parameters that are adjusted on the foresail are; Lateral Lead (barberhauler), Lead position (lead car), Sheet tension, and Luff tension (halyard).
Acceleration Gear: The objective is increase power, reduce aspect ratio and minimize leeway. Maximum acceleration is required when going from well below the target speed, such as when luffing at the starting line, to the target speed. Mainsail: The boom position is set wide (~6" off the centerline). The backstay tension is reduced and checkstay is tightened, which straightens the mast, increasing the depth of the draft. The draft is made full by easing the outhaul. The draft position is moved as far forward as possible by tensioning the cunningham. The leech of the main is allowed to twist markedly, by easing the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned in-board. The leadcar is set forward of its normal position. The sheet tension is minimal. The luff tension is minimal.
Speed Gear: The objective is to maximize speed while continuing to steer reasonably close to the wind. This gear is used to punch through waves or to work out from a leeward position or to power across the bow of a starboard crossing boat. Mainsail: The boom position is set close (~2" off the centerline). The backstay tension is moderate and checkstay tension is moderate, which bends the mast, decreasing the depth of the draft. The draft is made moderately full by trimming the outhaul. The draft position is moved aft by easing the cunningham. The leech of the main is gradually straightened, by trimming the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned normally. The leadcar is set to its normal position. The sheet tension is moderate. The luff tension is moderate.
Pointing Gear: This gear is used only when the boat is already at the target speed. Shifting into pointing gear when not a full speed will markedly increase leeway and reduce VMG. However, this is a great way to work up on a boat that you are lee-bowing or controlling at the approach to a windward mark. Mainsail: The boom position is set to the centerline. The backstay tension is increased and checkstay tension is minimal, which bends the mast, decreasing the depth of the draft. The draft is further flattened by trimming the outhaul. The draft position is moved aft by easing the cunningham. The leech of the main is straightened as much as possible, by trimming the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned in-board. The leadcar is set to a slightly aft position. The sheet tension is markedly tight. The luff tension is minimal.
Low Leeway Gear: Leeway is of major concern when moving slowly in light air and very heavy air conditions. Fortunately, the trim for the Acceleration gear (the loose, open, twisted leech on both the main and foresails) results in little leeway. Particularly in very light and very heavy air, the flattening of the sails by increasing mast bend gives superior performance. Mainsail: The boom position is set wide (~6" off the centerline). The backstay tension is maximum and checkstay is minimum, which bends the mast, flattening the sail. The draft is made flat by tightening the outhaul. The draft position is moved as far forward as possible by tensioning the cunningham. The leech of the main is allowed to twist moderately, by easing the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned out-board. The leadcar is set aft of its normal position. The sheet tension is moderate. The luff tension is maximum
1. Lead position. This means setting the lead angle and fore-aft position of the sheet lead. The fore-aft lead is positioned by drawing an imaginary line from midluff through the clew to the deck. Midluff is the point at the luff directly ahead of the second set of telltales. Fine-tune the lead position by slowly rounding into the wind and watching the telltales. All the weather telltales should flip up at once, indicating that the top and bottom of the sail are trimmed equally. If the top luffs first, move the lead forward; if the bottom luffs first, move the lead back. It is best to err on the side of too far back. This increases twist and gives the sail a larger "sweet spot".
2. Trim. Trim the sail close to, but not touching, the spreaders. The optimum trim may put the leech slightly in or out from this setting, with some variation according to sea and wind conditions.
3. Halyard Tension. Use halyard tension to pull the draft forward, but do not tension the halyard so much that you get a vertical wrinkle behind the headstay. Never overtension the halyard, watch the halyard marks.
4. Adjustments. In flat water and medium air, trim harder and move the lead angle in-board to flatten the sail and narrow the angle of attack. Tighten the backstay to reduce headstay sag and flatten the entry. In waves, ease the sheet, move the lead outboard, and sail lower angles to maintain speed. Ease the halyard slightly and ease the backstay if the rig doesn't move around too much. For heavy air, move the lead outboard, but keep the sheet and halyard in hard to keep the sail flat. Move the lead aft to free the upper leech and flatten the head--tolerate a slightly earlier luff in the top of the sail if necessary. For very light winds, move the lead outboard, ease the sheet and move the lead forward enough to maintain an even break along the luff. Use light backstay and halyard tension, and sail with the leeward telltale on the verge of stalling.
5. Effect on the mainsail. If the main is fluttering or backwinding excessively and all other setting are correct, move the headsail lead outboard or change to a flatter or smaller headsail.
6. Using the correct sail. The following table provides a guide for selecting the correct sail.
Genoa Wind Ranges
(for reference only, check with your sailmaker!)
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||
| Sail | Apparent wind range | Maximum Apparent Wind |
| #1 Light | 0-12 | 12 |
| #1 Medium | 6-20 | 20 |
| #1 Heavy | 15-23 | 23 |
| #2 | 21-27 | 27 |
| #3 | 24-34 | 34 |
| #4 | 31-45 | 45 |
7. Record the settings. When the boat is sailing fast, record the settings on a Genoa Trim Card.
GENOA TRIM CARD
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|||
| Genoa: | LOW END | MIDRANGE | HIGH END |
| Wind Range (Kts apparent) | |||
| Maximum Wind Speed (from sailmaker) | |||
| Lead Angle (degrees) | |||
| Lead Position (tape number) | |||
| Distance to Upper Spreader | |||
| Distance to Chainplates | |||
| Depth (% at midstripe) | |||
| Draft Position (% at mid) | |||
| Backstay Tension (Lbs.) | |||
| Halyard Tension (" from mark) | |||
Mainsail Upwind Trim:
1. Sheet tension and Traveler Position. Tighten the sheet and set the traveler car position so that the boom is roughly on the centerline of the boat. If the boat is getting overpowered (excessive weather helm) let the boom fall to leeward until back under control.
2. Trimming the upper batten. Trim the mainsheet until the top batten is parallel to the boom. Assuming that the main has the correct vertical curvature, draft distribution and sectional shape, this will bring the elements of twist, camber, angle of attack and power to the correct settings. To determine the angle between the top batten and boom, crouch under the boom and sight upward, lining up the reference points.
3. Main telltales. When trimmed correctly, the telltale on the top batten should be streaming aft most of the time and stalling (curling behind the main) once in a while. In ideal conditions--flat water and medium air-- trim the mainsheet harder so that the top telltale is stalled most of the time and the top batten hooks slightly to windward.
4. Leech tension. This is used to control helm and pointing. The tighter the leech the more helm and the higher the boat will point. Remember, however, that you must have speed before shifting into the pointing mode.
5. Traveler position. Use the traveler as the accelerator. When you need more speed, drop the traveler to leeward and foot off a few degrees. Trade speed for pointing by pulling the traveler to windward and pointing higher.
6. Position of maximum draft. The maximum draft should be positioned roughly 48-50% oft from the luff. Move draft forward when power is needed for acceleration or punching through waves. Use the cunningham rope to control the draft position. Pull it just tight enough to remove most of the wrinkles along the luff. New sails may be fastest with a few wrinkles showing.
7. Flatten in heavy air and smooth water. Flatten the main by increasing the amount of mast bend. This is done by increasing backstay tension, which also reduces headstay sag and is desirable. Watch for "overbend wrinkles" that extend from the lower-middle part of the mast to the clew. This indicates that the sail has reached maximum flatness and additional adjustment is overstressing the rig.
8. Fuller main for light air or waves. Increase the fullness of the main for light air or waves by reducing the backstay tension. Be careful not to allow too much headstay sag.
9. Target depth and draft positions.
Mainsail: Target
Depths and Draft Positions
|
||||||
| Apparent Wind (Knots) | Lower Stripe Depth (%) | Lower Stripe Position (%) | Middle Stripe Depth (%) | Middle Stripe Position (%) | Upper Stripe Depth (%) | Upper Stripe Position (%) |
| 3-6 | 14-15 | 45 | 15-16 | 45 | 16-17 | 45 |
| 5-12 | 12 | 50 | 14-15 | 50 | 15-16 | 50 |
| 10-18 | 10 | 50 | 12-13 | 50 | 13-14 | 50 |
| 16-26 | 8-9 | 50 | 11 | 50 | 11 | 50 |
| 24-30 | 9 | 50 | 10 | 50 | 10 | 50 |
These are general targets only and need to vary depending on the sail and boat.
Mainsail Downwind trim:
1. Trim for "backwind". Ease the sheet until you just start to see backwind or luffing along the luff edge of the sail. Play the main sheet to keep the sail on the edge of luffing.
2. Outhaul and Cunningham. Ease the outhaul and cunningham to make the sail fuller. The halyard may also need to be eased if vertical wrinkles along the luff are seen.
3. Trimming the upper batten. Adjust the mainsheet and vang so that the upper batten is parallel to the boom. On reaches set the leech so the upper-batten telltale streams aft most of the time. This minimizes backwind from the lower leech of the genoa or spinnaker.
4. Vang. Be careful not to overdo the vang in light and medium air. In these conditions the weight of the boom is enough to provide the leech tension. On heavy-air runs, use lots of vang. This reduces the upper leech twist which makes the boat want to roll. To damped rolling, sheet in.
5. Over powered reach. Leave the outhaul tight. Ease the vang enough to keep the end of boom out of the water when rolling. Dump the sheet when the heel becomes too great. If the boom end drags in the water a lot, reef the main.
6. Light air. Have a crew member hold the boom out, especially if heeling to windward. Make sure the pressure is out and not down.
7. Trimming order. The headsail, genoa or spinnaker is trimmed first. The headsail trimmer must tell the main-trimmer when making a change.
MAIN TRIM CARD
|
|||
| Mainsail: | Light Air | Medium | Heavy Air |
| Wind Range (Kts apparent) | |||
| Top Batten (angle to boom) | |||
| Outhaul (inches to band) | |||
| Cunningham (none, little, hard) | |||
| Depth (% at midstripe) | |||
| Draft Position (% at mid) | |||
| Backstay Tension (Lbs.) | |||
| Boom Position | |||
| Battens | |||
| Rudder Angle (degrees) | |||
Shifting Gears:
When working to windward, and especially at the start, the sails can be trimmed to maximize; 1) Acceleration, 2) Speed, 3) Pointing and 4) Low Leeway. The following are general guidelines for trimming to each 'gear'. The trim parameters that are adjusted on the main are; Sheeting angle (boom position), Mast bend (backstay tension & checkstay tension), Draft (outhaul), Draft position (cunningham), and Twist (mainsheet). The trim parameters that are adjusted on the foresail are; Lateral Lead (barberhauler), Lead position (lead car), Sheet tension, and Luff tension (halyard).
Acceleration Gear: The objective is increase power, reduce aspect ratio and minimize leeway. Maximum acceleration is required when going from well below the target speed, such as when luffing at the starting line, to the target speed. Mainsail: The boom position is set wide (~6" off the centerline). The backstay tension is reduced and checkstay is tightened, which straightens the mast, increasing the depth of the draft. The draft is made full by easing the outhaul. The draft position is moved as far forward as possible by tensioning the cunningham. The leech of the main is allowed to twist markedly, by easing the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned in-board. The leadcar is set forward of its normal position. The sheet tension is minimal. The luff tension is minimal.
Speed Gear: The objective is to maximize speed while continuing to steer reasonably close to the wind. This gear is used to punch through waves or to work out from a leeward position or to power across the bow of a starboard crossing boat. Mainsail: The boom position is set close (~2" off the centerline). The backstay tension is moderate and checkstay tension is moderate, which bends the mast, decreasing the depth of the draft. The draft is made moderately full by trimming the outhaul. The draft position is moved aft by easing the cunningham. The leech of the main is gradually straightened, by trimming the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned normally. The leadcar is set to its normal position. The sheet tension is moderate. The luff tension is moderate.
Pointing Gear: This gear is used only when the boat is already at the target speed. Shifting into pointing gear when not a full speed will markedly increase leeway and reduce VMG. However, this is a great way to work up on a boat that you are lee-bowing or controlling at the approach to a windward mark. Mainsail: The boom position is set to the centerline. The backstay tension is increased and checkstay tension is minimal, which bends the mast, decreasing the depth of the draft. The draft is further flattened by trimming the outhaul. The draft position is moved aft by easing the cunningham. The leech of the main is straightened as much as possible, by trimming the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned in-board. The leadcar is set to a slightly aft position. The sheet tension is markedly tight. The luff tension is minimal.
Low Leeway Gear: Leeway is of major concern when moving slowly in light air and very heavy air conditions. Fortunately, the trim for the Acceleration gear (the loose, open, twisted leech on both the main and foresails) results in little leeway. Particularly in very light and very heavy air, the flattening of the sails by increasing mast bend gives superior performance. Mainsail: The boom position is set wide (~6" off the centerline). The backstay tension is maximum and checkstay is minimum, which bends the mast, flattening the sail. The draft is made flat by tightening the outhaul. The draft position is moved as far forward as possible by tensioning the cunningham. The leech of the main is allowed to twist moderately, by easing the mainsheet, while controlling the boom position with the traveler. Foresail: The lateral lead is positioned out-board. The leadcar is set aft of its normal position. The sheet tension is moderate. The luff tension is maximum
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