My Hunter 216 has a topping lift line ( no backstay). The boat seems to sail faster with the line tight (sail curved), instead of the line "relaxed" and the sail flat. Does that make "sail" sense?
Sail Shape Question
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It makes perfect sence.. The object to sail shape is to tame the wind over the shape of the sail, and not to stop it. Like a wing on a plane, the shape of the structure causes lift of the wing as the wind is propelled over it.
You'll find that in many cases, ugly is fast and a nice neet trim sail is pretty but rather slow....
You'll find that in many cases, ugly is fast and a nice neet trim sail is pretty but rather slow....
Mainsail shape
The topping lift is designed to hold the boom in place when the mainsail is not up and has no bearing as to whether you have a backstay or not. You probably knew that, but in case you were thinking they were related, I thought I would bring that up.
Sail shape is something that one changes constantly for better performance as conditions change, or your course changes in relationship to the wind.
Usually when you want a very flat sail it is in heavier air situations.
Think of these sail controls (whether it be main or jib or genoa):
If you tighten the halyard (or cunningham on the main, if your boat has one), you bring the draft of the sail forward towards the luff.
If you tighten the outhaul on the boom, that brings the draft from the foot upward.
If you loosen either, that brings the draft aft or down respectively.
In heavier air, you want to tighten the outhaul (on the main) and the luff on the main and jib. This brings the draft forward for more power.
In heavy air you want to tighten up the boom vang to flatten the mainsail even more. If you have a traveler, then you want to start lowering the car to leeward as the wind increases.
If you had a backstay, you could tighten that (if adjustable) which would bend the mast and that helps in heavy air as well.
The twist of the mainsail at the leech is controlled by the vang and the mainsheet. Ease off the vang and that adds more twist in the trailing edge of the mainsail. Tighten the vang and that straightens the twist in the trailing edge of the mainsail.
As you crack off the wind (fall off), hence easing your genoa and main sheet, you can also ease off the vang so that the twist in the mainsail increases (or twists off - opens up) and then both sails match each other for better performance.
If you are sailing in light air, you want everything loose. Bring your traveler up to weather and trim the mainsheet for the course you are on (close hauled, beam reach, broad reach, etc.). When in doubt, let it out.
Most people wonder why their boat is sailing so slow and most often it is because they have everything too tight.
If you have a tension curl in the luff of the sails, you are too tight for the conditions. As the wind increases, you can add halyard tension until you get that tension curl. Then ease off a bit.
When the wind is light, you can ease off the halyards so the luff is light. But, never to the point where you have sags between the hanks on your jib. You want a straight luff.
As the wind increases ease the traveler to leeward. If a gust comes through, then let off the traveler down to leeward, but not the mainsheet.
Let off the sheet only if possible. Dumping the traveler keeps the boat on her feet without changing the mainsail trim.
Boats like Hunters that have the traveler on top of the arch might not be able to do this. A big downside to that design for efficient sailing. In that case, you would dump the mainsheet. Often the mainsheet leading to the traveler or single block location on an arch has an angle too far aft for efficient boom down haul for any effectiveness to help control twist. Another poor design feature of boats with no backstay and an arch from a performance perspective.
Something else to consider is the genoa lead block location. That is the location of the block on the track that your jib sheet leads through back to your primary winch in the cockpit. If you have a furler, or if you use different size hank on headsails, then the block location will change as the different size sails are used or the headsail is reefed with the furling system. It never is the same location.
The goal is to have the headsail luff break all at the same time. In other words, sailing close hauled (and you should do this, with the jib or genoa sheet in tight as you sail as close as you can to the wind) gradually point the boat into the wind (slowly) and let the leading edge of your headsail (luff) break. If the genoa lead is in the correct location, the entire luff or leading edge of your sail will break from top to bottom at the same time.
If it breaks on the upper half before the lower half, your lead is too far aft. If your headsail breaks first on the lower half before the upper half, your lead is too far forward. Keep experimenting by moving the lead fore or aft until the the luff breaks all at the same time. Then you know you will have the best location for normal conditions for best genoa performance to weather.
If you are in very heavy air and you need to depower your sailplan, you can move your genoa lead aft which makes the upper half of the sail luff first enabling you to sail flatter without decreasing your sail area. Just an extra tip.
I hope this helps. A good book on sail trim might help for more information. Even if you are a cruiser and not a racer, it is nice to make your boat sail her best for more fun and involvement in learning your boat, plus you get to your next destination sooner, especially if you are trying to reach landfall before dark, or to meet a schedule.
The topping lift is designed to hold the boom in place when the mainsail is not up and has no bearing as to whether you have a backstay or not. You probably knew that, but in case you were thinking they were related, I thought I would bring that up.
Sail shape is something that one changes constantly for better performance as conditions change, or your course changes in relationship to the wind.
Usually when you want a very flat sail it is in heavier air situations.
Think of these sail controls (whether it be main or jib or genoa):
If you tighten the halyard (or cunningham on the main, if your boat has one), you bring the draft of the sail forward towards the luff.
If you tighten the outhaul on the boom, that brings the draft from the foot upward.
If you loosen either, that brings the draft aft or down respectively.
In heavier air, you want to tighten the outhaul (on the main) and the luff on the main and jib. This brings the draft forward for more power.
In heavy air you want to tighten up the boom vang to flatten the mainsail even more. If you have a traveler, then you want to start lowering the car to leeward as the wind increases.
If you had a backstay, you could tighten that (if adjustable) which would bend the mast and that helps in heavy air as well.
The twist of the mainsail at the leech is controlled by the vang and the mainsheet. Ease off the vang and that adds more twist in the trailing edge of the mainsail. Tighten the vang and that straightens the twist in the trailing edge of the mainsail.
As you crack off the wind (fall off), hence easing your genoa and main sheet, you can also ease off the vang so that the twist in the mainsail increases (or twists off - opens up) and then both sails match each other for better performance.
If you are sailing in light air, you want everything loose. Bring your traveler up to weather and trim the mainsheet for the course you are on (close hauled, beam reach, broad reach, etc.). When in doubt, let it out.
Most people wonder why their boat is sailing so slow and most often it is because they have everything too tight.
If you have a tension curl in the luff of the sails, you are too tight for the conditions. As the wind increases, you can add halyard tension until you get that tension curl. Then ease off a bit.
When the wind is light, you can ease off the halyards so the luff is light. But, never to the point where you have sags between the hanks on your jib. You want a straight luff.
As the wind increases ease the traveler to leeward. If a gust comes through, then let off the traveler down to leeward, but not the mainsheet.
Let off the sheet only if possible. Dumping the traveler keeps the boat on her feet without changing the mainsail trim.
Boats like Hunters that have the traveler on top of the arch might not be able to do this. A big downside to that design for efficient sailing. In that case, you would dump the mainsheet. Often the mainsheet leading to the traveler or single block location on an arch has an angle too far aft for efficient boom down haul for any effectiveness to help control twist. Another poor design feature of boats with no backstay and an arch from a performance perspective.
Something else to consider is the genoa lead block location. That is the location of the block on the track that your jib sheet leads through back to your primary winch in the cockpit. If you have a furler, or if you use different size hank on headsails, then the block location will change as the different size sails are used or the headsail is reefed with the furling system. It never is the same location.
The goal is to have the headsail luff break all at the same time. In other words, sailing close hauled (and you should do this, with the jib or genoa sheet in tight as you sail as close as you can to the wind) gradually point the boat into the wind (slowly) and let the leading edge of your headsail (luff) break. If the genoa lead is in the correct location, the entire luff or leading edge of your sail will break from top to bottom at the same time.
If it breaks on the upper half before the lower half, your lead is too far aft. If your headsail breaks first on the lower half before the upper half, your lead is too far forward. Keep experimenting by moving the lead fore or aft until the the luff breaks all at the same time. Then you know you will have the best location for normal conditions for best genoa performance to weather.
If you are in very heavy air and you need to depower your sailplan, you can move your genoa lead aft which makes the upper half of the sail luff first enabling you to sail flatter without decreasing your sail area. Just an extra tip.
I hope this helps. A good book on sail trim might help for more information. Even if you are a cruiser and not a racer, it is nice to make your boat sail her best for more fun and involvement in learning your boat, plus you get to your next destination sooner, especially if you are trying to reach landfall before dark, or to meet a schedule.
Sail shape, sail power and the topping lift
I agree with Randy that sail trim should not be based on how your sails look but rather on whether or not you get the performance (boatspeed, in this case) you want. I sometimes sail with "ugly" trim, especially in heavy air, because it keeps my boat under control and up to speed. However, I don't think the answer to your question is that simple. For example, you didn't mentioned wind speed or point of sail.
Conventional wisdom says not to use the topping lift for sail trim because it compromises the utility of the mainsheet, which is the primary mainsail control. However, one exception is when sailing in very light air (especially off the wind) when the weight of the boom pulls the leech of the sail tight, reducing what little available power there is. Tightening the topping lift takes the weight of the boom off the sail, allowing it to assume a more beneficial shape for those light-air conditions.
Sail power has two main components; wind speed and sail shape. The former is pretty simple. Higher wind speed yields more power, in fact I'm told power is related to the square of windspeed.
More curve (deeper draft) in a sail creates more power. This is useful at low wind speeds, just as flaps on an airplane wing create additional lift at low airspeed. As the wind speed increases, the additional wind pressure on the sail will deepen its curve even more, adding to the curve already induced by the tensioned topping lift and creating even more power. The topping lift should be slacked off and the sail may even have to be flattened further as needed to suit the higher windspeed. Too much power can be a nuisance (excessive heel and weather helm) or it can lead to something more serious like knockdown or capsize. As a frequent small boat sailor, I can attest to this from personal experience.
Much has been written here about sail trim over the years. A review of the articles in the Sail Trim Forum and in the Smaller Boats Forum will provide a lot of insight. I also highly recommend Don Guillette's Guide to Sail Trim, available right here at Sailboatowners.com. If you want to read further, I suggest Bill Gladstone's "Trim", part of the North U. training manual series published by North Sails.
One of the things I love about sailing is that there's always something new to learn. It's been said that, "You can learn to sail in an afternoon, but learning to sail well will take the rest of your life." Good luck and happy sailing.
Peter
H23 "Raven"
I agree with Randy that sail trim should not be based on how your sails look but rather on whether or not you get the performance (boatspeed, in this case) you want. I sometimes sail with "ugly" trim, especially in heavy air, because it keeps my boat under control and up to speed. However, I don't think the answer to your question is that simple. For example, you didn't mentioned wind speed or point of sail.
Conventional wisdom says not to use the topping lift for sail trim because it compromises the utility of the mainsheet, which is the primary mainsail control. However, one exception is when sailing in very light air (especially off the wind) when the weight of the boom pulls the leech of the sail tight, reducing what little available power there is. Tightening the topping lift takes the weight of the boom off the sail, allowing it to assume a more beneficial shape for those light-air conditions.
Sail power has two main components; wind speed and sail shape. The former is pretty simple. Higher wind speed yields more power, in fact I'm told power is related to the square of windspeed.
More curve (deeper draft) in a sail creates more power. This is useful at low wind speeds, just as flaps on an airplane wing create additional lift at low airspeed. As the wind speed increases, the additional wind pressure on the sail will deepen its curve even more, adding to the curve already induced by the tensioned topping lift and creating even more power. The topping lift should be slacked off and the sail may even have to be flattened further as needed to suit the higher windspeed. Too much power can be a nuisance (excessive heel and weather helm) or it can lead to something more serious like knockdown or capsize. As a frequent small boat sailor, I can attest to this from personal experience.
Much has been written here about sail trim over the years. A review of the articles in the Sail Trim Forum and in the Smaller Boats Forum will provide a lot of insight. I also highly recommend Don Guillette's Guide to Sail Trim, available right here at Sailboatowners.com. If you want to read further, I suggest Bill Gladstone's "Trim", part of the North U. training manual series published by North Sails.
One of the things I love about sailing is that there's always something new to learn. It's been said that, "You can learn to sail in an afternoon, but learning to sail well will take the rest of your life." Good luck and happy sailing.
Peter
H23 "Raven"
Also Look Under The Forums
tab, "Expert Forums" and then "Sail Trim Forum" for links to Don Guillette's book and charts on sail trim. I personally can not speak highly enough for these documents. What I have found to be invaluable is to get the book, read it a couple times, get the book in a protective cover, get on the boat in the cockpit, get out there in the wind with the tiller or wheel in your hand, set the sails and then look at what your conditions are, read the section again and look, see and do. It works so easy and if you just keep reading the book and then looking at the conditions and doing what Don says, the next thing you know you are sailing along and really knowing about what is going on. It is so neat
and really makes sailing become something that is so much more fun and enjoyable, you will get a lot more satisfaction from it. Go check his forum out, you will be glad you did.
tab, "Expert Forums" and then "Sail Trim Forum" for links to Don Guillette's book and charts on sail trim. I personally can not speak highly enough for these documents. What I have found to be invaluable is to get the book, read it a couple times, get the book in a protective cover, get on the boat in the cockpit, get out there in the wind with the tiller or wheel in your hand, set the sails and then look at what your conditions are, read the section again and look, see and do. It works so easy and if you just keep reading the book and then looking at the conditions and doing what Don says, the next thing you know you are sailing along and really knowing about what is going on. It is so neat
and really makes sailing become something that is so much more fun and enjoyable, you will get a lot more satisfaction from it. Go check his forum out, you will be glad you did.- Status