In the latest sail magazine. their is an article on twisting a mainsail. what they say makes sense, but. How do you do this? opening a batton , opening and or closing a clew and or leech? I'm a novice sailor. I know these by terminology but not exactly how you go about using them properly? the article assumes its readers already understand all of this. Any help is apprecitated. thank you bryan
main sheet trim
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Vang = Twist
It is easy to add twist to the mainsail. Ease the boomvang which inturn allows the boom to raise up and this causes the mainsail to twist. I add twist to the main on a broad reach or downwind points of sail.
It is easy to add twist to the mainsail. Ease the boomvang which inturn allows the boom to raise up and this causes the mainsail to twist. I add twist to the main on a broad reach or downwind points of sail.
I will try explain, but....
...I strongly recommend Don Guillete's book 'The Sail Trim Users Guide' which is sold in the chandlery of this website. It's worth every penny and then some. Here goes, Twist is nothing more than the sag of the leech of the sail. Twist is added into a sail as the wind builds and the boat becomes overpowered. The higher off the deck the stronger the wind (usually). By easing the main sheet, you increase the sag (twist) in the leech which spills some of the wind out of the top part of the main. This stalls the sail in the top leaving the lower part of the sail to drive the boat, but with less heeling force. Most sailors have far too much twist in the main. A twisted off main is sailing inefficiently. When the wind pipes up that is what you need, but for winds of 10-12kts there is need for very little if any twist. Hope, this helps, but buy the book!!
...I strongly recommend Don Guillete's book 'The Sail Trim Users Guide' which is sold in the chandlery of this website. It's worth every penny and then some. Here goes, Twist is nothing more than the sag of the leech of the sail. Twist is added into a sail as the wind builds and the boat becomes overpowered. The higher off the deck the stronger the wind (usually). By easing the main sheet, you increase the sag (twist) in the leech which spills some of the wind out of the top part of the main. This stalls the sail in the top leaving the lower part of the sail to drive the boat, but with less heeling force. Most sailors have far too much twist in the main. A twisted off main is sailing inefficiently. When the wind pipes up that is what you need, but for winds of 10-12kts there is need for very little if any twist. Hope, this helps, but buy the book!!
twist and shout...
Sail shape! More mysterious by far than the Trinity itself... and there are lots of opinions, and all of them are right, to some degree. Possibly even mine. Using the boomvang to provide or release downward pressure on the boom is clearly one excellent method of controlling twist... lots of folks also control mainsail twist by changing the relative position of the mainsheet traveller in response to wind strength. In light winds, with the traveller to windward, and lets just say you have the boom sheeted in to the centerline of the boat, the angle of the sheet to the boom becomes relatiavely horizontal, allowing the boom to rise, and the sail to twist. This allows a reduced angle of attack at the top of the sail, where the wind is probably stronger than it is toward the bottom. Conversely, in stiff winds, easing the traveller to leeward while sheeting in the main as necessary causes the sheet to act at a more vertical angle,exerting a downward force on the boom, flattening the main, and reducing twist. Both methods are used in tandem, of course, depending on the ease of adjusting your traveller and that of altering the tension on your vang. On MY boat, adjusting the traveller is easier, especially when you're drunk; although, every time you change the positon of the traveller, on a given point of sail, you'll need to make a corresponding change to the tension on the mainsheet. And vice versa. Unless you're just too drunk to care. Just kidding. On the other hand (again, on MY boat) adding or releasing pressure on the vang will generally yield good results throughout various points of sail, but to maintain proper sail shape you will need to alter vang tension as you encounter differences in wind strength. I'm sure this is either too elementary, or too badly written, to be of any use, but I betcha you'll get lots more articulate responses from others in the forum. Have fun! RJ
Sail shape! More mysterious by far than the Trinity itself... and there are lots of opinions, and all of them are right, to some degree. Possibly even mine. Using the boomvang to provide or release downward pressure on the boom is clearly one excellent method of controlling twist... lots of folks also control mainsail twist by changing the relative position of the mainsheet traveller in response to wind strength. In light winds, with the traveller to windward, and lets just say you have the boom sheeted in to the centerline of the boat, the angle of the sheet to the boom becomes relatiavely horizontal, allowing the boom to rise, and the sail to twist. This allows a reduced angle of attack at the top of the sail, where the wind is probably stronger than it is toward the bottom. Conversely, in stiff winds, easing the traveller to leeward while sheeting in the main as necessary causes the sheet to act at a more vertical angle,exerting a downward force on the boom, flattening the main, and reducing twist. Both methods are used in tandem, of course, depending on the ease of adjusting your traveller and that of altering the tension on your vang. On MY boat, adjusting the traveller is easier, especially when you're drunk; although, every time you change the positon of the traveller, on a given point of sail, you'll need to make a corresponding change to the tension on the mainsheet. And vice versa. Unless you're just too drunk to care. Just kidding. On the other hand (again, on MY boat) adding or releasing pressure on the vang will generally yield good results throughout various points of sail, but to maintain proper sail shape you will need to alter vang tension as you encounter differences in wind strength. I'm sure this is either too elementary, or too badly written, to be of any use, but I betcha you'll get lots more articulate responses from others in the forum. Have fun! RJ
Good info on line
Sail trim is sometimes difficult to understand for those of us who are learning - articles explain it but then when we are out there .... did we bring a copy of the article?. Did it say to tighten the leach or open it out and how do I do that? Many suggest buying the sail trim book/chart available here by Don Guillette - certainly you can check the archives for a number of postings. Other sources whcih I have found usefull include: http://www.wb-sails.fi/news/95_11_Tellingtales/Tellingtales.html and http://www.sailnet.com/collections/racing/sailtrim/index.cfm Check these out - hope they help. James
Sail trim is sometimes difficult to understand for those of us who are learning - articles explain it but then when we are out there .... did we bring a copy of the article?. Did it say to tighten the leach or open it out and how do I do that? Many suggest buying the sail trim book/chart available here by Don Guillette - certainly you can check the archives for a number of postings. Other sources whcih I have found usefull include: http://www.wb-sails.fi/news/95_11_Tellingtales/Tellingtales.html and http://www.sailnet.com/collections/racing/sailtrim/index.cfm Check these out - hope they help. James
OK, I'll take a stab at it, Bryan
Here's my attempt. Forgive me if I sound a bit condescending but since you said you were a novice I'd rather assume you know very little and run the risk of offending you than assume you know some more and lose you in the jargon (and end up not helping you at all). A couple of definitions (it may help to get a piece of paper and sketch this as you read): The "chord" of the sail is an imaginary, straight, horizontal line that joins the luff (leading edge) and leech (trailing edge) of the sail when viewed from above. The chord most people recognize is the boom, but you can have a chord at any height on the sail. The "angle of attack" is the angle that a chord makes with the apparent wind. The angle of attack with which most people are familiar is the angle of the boom to the wind. A sail must have an angle of attack to develop lift. A sail that is flapping like a flag ("luffing")has zero angle of attack and develops no lift. In simple terms, more angle of attack = more power = more boatspeed) but you can overdo it. More on this in a bit. "Twist" is the change (usually a decrease) in the angle of attack as you go up the sail. This occurs naturally in a sail because the leech is not rigid but rather is forced into a curve by the air flowing over it. Leech tension and the amount of twist are easily adjusted. If you tighten ("close") the leech, the sail conforms more to the angle of attack of the boom and there is less twist. If you loosen ("open") the leech, the opposite occurs and there is more twist. More leech tension = less twist = higher angle of attack = more power, and vice versa. Leech tension and twist are controlled by pulling down on the boom. The mainsheet does this when sailing upwind. As you sheet in initially, the boom swings inboard, its angle of attack increases and you get more power. As you sheet in more, you will get to a point where the boom won't come in any more and the mainsheet starts pulling the boom down. This tensions the leech, decreases twist, increases angle of attack higher up on the sail and generates even more power. However, sailing is all about balance and TOO MUCH power isn't good either, especially power towards the top of the sail. If the breeze continues to build, the sail can overpower the boat. An overpowered boat heels excessively, slows down and needs more helm to keep from turning up into the wind ("weather helm"). The solution is to depower the sail, either by reducing its area ("reefing") or by spilling some air. Instead of dumping the mainsheet and rapidly reducing the angle of attack of the entire sail, ease the mainsheet slightly so the boom can rise a bit. Behold! The leech opens, the top of the sail twists off, the angle of attack at the top of is reduced and the sail is depowered. Less power high up on the sail means less heel. However, the bottom of the sail remains at the proper angle of attack and is still generating useful power. i.e. boatspeed. Less heel and less weather helm mean less drag too. This is how twist works in your favor. How do know how much to ease? With a little practice you can do it by feel as the helm lightens noticeably. You can also tell by the boatspeed (it should increase slightly), the angle of heel (15 to 20 degrees max. depending on the boat) or the screaming from your guests (it should diminish to a low murmur). The top batten is also a useful indicator. Sail theoreticians say the top batten should be parallel to the boom for proper mainsail trim. This indicates that the angle of attack is the same all the way up, i.e. no sail twist and maximum power. However, a "properly trimmed" mainsail may be too powerful under certain conditions. If you ease the mainsheet, the leech opens, the top of the sail twists off and the top batten points off to leeward. Trim your sail for speed and comfort, not for how "proper" it looks. There are other ways to adjust twist when sailing upwind, but I'll stop here. For the record, you can twist the headsail (jib) too, but you need adjustable jib leads for that. I'll save that one for next time. Sorry this turned out to be so long but I tried to explain not only what to do but why you do it. I hope it helps. Happy sailing. Peter H23 "Raven"
Here's my attempt. Forgive me if I sound a bit condescending but since you said you were a novice I'd rather assume you know very little and run the risk of offending you than assume you know some more and lose you in the jargon (and end up not helping you at all). A couple of definitions (it may help to get a piece of paper and sketch this as you read): The "chord" of the sail is an imaginary, straight, horizontal line that joins the luff (leading edge) and leech (trailing edge) of the sail when viewed from above. The chord most people recognize is the boom, but you can have a chord at any height on the sail. The "angle of attack" is the angle that a chord makes with the apparent wind. The angle of attack with which most people are familiar is the angle of the boom to the wind. A sail must have an angle of attack to develop lift. A sail that is flapping like a flag ("luffing")has zero angle of attack and develops no lift. In simple terms, more angle of attack = more power = more boatspeed) but you can overdo it. More on this in a bit. "Twist" is the change (usually a decrease) in the angle of attack as you go up the sail. This occurs naturally in a sail because the leech is not rigid but rather is forced into a curve by the air flowing over it. Leech tension and the amount of twist are easily adjusted. If you tighten ("close") the leech, the sail conforms more to the angle of attack of the boom and there is less twist. If you loosen ("open") the leech, the opposite occurs and there is more twist. More leech tension = less twist = higher angle of attack = more power, and vice versa. Leech tension and twist are controlled by pulling down on the boom. The mainsheet does this when sailing upwind. As you sheet in initially, the boom swings inboard, its angle of attack increases and you get more power. As you sheet in more, you will get to a point where the boom won't come in any more and the mainsheet starts pulling the boom down. This tensions the leech, decreases twist, increases angle of attack higher up on the sail and generates even more power. However, sailing is all about balance and TOO MUCH power isn't good either, especially power towards the top of the sail. If the breeze continues to build, the sail can overpower the boat. An overpowered boat heels excessively, slows down and needs more helm to keep from turning up into the wind ("weather helm"). The solution is to depower the sail, either by reducing its area ("reefing") or by spilling some air. Instead of dumping the mainsheet and rapidly reducing the angle of attack of the entire sail, ease the mainsheet slightly so the boom can rise a bit. Behold! The leech opens, the top of the sail twists off, the angle of attack at the top of is reduced and the sail is depowered. Less power high up on the sail means less heel. However, the bottom of the sail remains at the proper angle of attack and is still generating useful power. i.e. boatspeed. Less heel and less weather helm mean less drag too. This is how twist works in your favor. How do know how much to ease? With a little practice you can do it by feel as the helm lightens noticeably. You can also tell by the boatspeed (it should increase slightly), the angle of heel (15 to 20 degrees max. depending on the boat) or the screaming from your guests (it should diminish to a low murmur). The top batten is also a useful indicator. Sail theoreticians say the top batten should be parallel to the boom for proper mainsail trim. This indicates that the angle of attack is the same all the way up, i.e. no sail twist and maximum power. However, a "properly trimmed" mainsail may be too powerful under certain conditions. If you ease the mainsheet, the leech opens, the top of the sail twists off and the top batten points off to leeward. Trim your sail for speed and comfort, not for how "proper" it looks. There are other ways to adjust twist when sailing upwind, but I'll stop here. For the record, you can twist the headsail (jib) too, but you need adjustable jib leads for that. I'll save that one for next time. Sorry this turned out to be so long but I tried to explain not only what to do but why you do it. I hope it helps. Happy sailing. Peter H23 "Raven"
More sources of information
Don Guilette's book is a useful primer at a price that's hard to beat. Unfortunately the edition I bought didn't cover fractional rigs with swept-back spreaders and bendy masts, which is the setup on my H23. I've attached a photo with lots of twist in the sails. You may also want to check out North Sails' North U. (for "university", I think) book on Trim, available at West Marine, also reasonably priced. Peter H23 "Raven"
Don Guilette's book is a useful primer at a price that's hard to beat. Unfortunately the edition I bought didn't cover fractional rigs with swept-back spreaders and bendy masts, which is the setup on my H23. I've attached a photo with lots of twist in the sails. You may also want to check out North Sails' North U. (for "university", I think) book on Trim, available at West Marine, also reasonably priced. Peter H23 "Raven"
Sail Trim Links
Some of my favorites: http://www.ipass.net/sailboat/tips.htm http://www.wb-sails.fi/news/99_1_AeroShape/Aero.htm http://www.wb-sails.fi/news/98_11_PerfectShape/Main.htm http://www.wb-sails.fi/news/95_11_Tellingtales/Tellingtales.html Happy sails *_/), MArk
Some of my favorites: http://www.ipass.net/sailboat/tips.htm http://www.wb-sails.fi/news/99_1_AeroShape/Aero.htm http://www.wb-sails.fi/news/98_11_PerfectShape/Main.htm http://www.wb-sails.fi/news/95_11_Tellingtales/Tellingtales.html Happy sails *_/), MArk
Dumb question
In this discussion, would it be useful for the layman to interpret "twist" as "sag" or "bulge" of the main?
In this discussion, would it be useful for the layman to interpret "twist" as "sag" or "bulge" of the main?
Besnow: Once you see a twisted sail you won't forget it. The problem is most authors use the traditional definitions for all aspects of sail trim and that confuses the blazes out of most begginers - it sure did me!! Additionally, once you know what twist looks like you'll see it all over the place as 75% of the people sail that way all the time. To see what a twisted main and jib looks like go to the message by PETER SUAH and click on the picture. Notice how the bottom 2/3 of both the main and jib are close hauled and the top 1/3 is on a beam reach. The top of the sail is spilling out air and power. Now that you know what it looks like - here's how you adjust it. The twist controls for the mainsail are the boom vang and the mainsheet. As you crank on the vang and the mainsheet, you reduce twist. In other words, the top portion starts to come in and looks like the bottom portion. Conversely, if you ease the vang and the mainsheet, the top will open up and you'll lose power. The sails will look like what Peter is trying to show. The twist control for the jib is the fairlead. Moving the fairlead forward decreases twist(makes top flatter) and moving it aft increases twist (opens the top). You want both the mainsail and jib to mirror each other so you want to adjust both. Next time you out sailing mess with the 3 sail trim controls I mentioned and watch the twist go in and out on the sail. Peter S: There is no difference in mainsail and jib trim for either a mast head or fractional rig. The thing with the fractional rig is that the mainsail is the engine (for the mast head rig it is the jib) and you have to pay more attention to what your doing with the mainsail. Peter i can't tell for sure but it looks like you have a boom vang. Next time your out, crank on it and move the fairlead forward, You boat should gain at least 1 knot of speed!!
Here is some twist
my main is somewhat blown out, big belly, sail loft told me to take some pics so they could figure out what to fix.
my main is somewhat blown out, big belly, sail loft told me to take some pics so they could figure out what to fix.
Mainsail trim...for Don G
Your assessment of the trim in my picture is on the money. I chose that picture specifically to show what twist looks like. What's not so easy to see in the picture are the conditions that led to that setup. Here's the rest of the story... It was a fairly windy day but the water was almost flat (short fetch) so I didn't need any extra power for punching through waves. The boat is light (2300 lb) with a shallow, cast-iron, wing keel (27-inch draft, so not a lot of righting moment), the hull is easily driven, and VC17 bottom paint makes it extra slippery. The H23 is beamy and doesn't like excessive heel. About 15 degrees is good, which is about where I had it. I was single-handing and not racing. To make a long story short, I was deliberately spilling air. As you correctly observed, the headsail is twisted too, to match the main and balance the sailplan. If you look at the tiller you'll see it's almost on center, i.e. almost no weather helm. The mast is bent, to flatten the sail and open the leech more. It wasn't perfect trim but under those conditions, I was sailing quickly and comfortably with all the power I needed. Speed really isn't an issue for this boat. She does 6 kt upwind in 12-15 kt of true wind which ain't bad for a waterline under 20 ft. The H23 also planes. I've done 8.6 kt and have heard of others exceeding 10 kt. I agree that good mainsail trim is important on a fractional rig. It took me a few years to grasp the concepts and I'm still learning. I also agree that most sail trim books lose you in the jargon. In addition, they all describe how to GET more power but most seem short on explaining how to manage it effectively, which is critical for a boat like mine that is easily overpowered. I found the North U. manual on trim to be quite good. Peter H23 "Raven"
Your assessment of the trim in my picture is on the money. I chose that picture specifically to show what twist looks like. What's not so easy to see in the picture are the conditions that led to that setup. Here's the rest of the story... It was a fairly windy day but the water was almost flat (short fetch) so I didn't need any extra power for punching through waves. The boat is light (2300 lb) with a shallow, cast-iron, wing keel (27-inch draft, so not a lot of righting moment), the hull is easily driven, and VC17 bottom paint makes it extra slippery. The H23 is beamy and doesn't like excessive heel. About 15 degrees is good, which is about where I had it. I was single-handing and not racing. To make a long story short, I was deliberately spilling air. As you correctly observed, the headsail is twisted too, to match the main and balance the sailplan. If you look at the tiller you'll see it's almost on center, i.e. almost no weather helm. The mast is bent, to flatten the sail and open the leech more. It wasn't perfect trim but under those conditions, I was sailing quickly and comfortably with all the power I needed. Speed really isn't an issue for this boat. She does 6 kt upwind in 12-15 kt of true wind which ain't bad for a waterline under 20 ft. The H23 also planes. I've done 8.6 kt and have heard of others exceeding 10 kt. I agree that good mainsail trim is important on a fractional rig. It took me a few years to grasp the concepts and I'm still learning. I also agree that most sail trim books lose you in the jargon. In addition, they all describe how to GET more power but most seem short on explaining how to manage it effectively, which is critical for a boat like mine that is easily overpowered. I found the North U. manual on trim to be quite good. Peter H23 "Raven"
Can't say without seeing the boom, Scott
But looking at the draft higher up I'd have to say your sail doesn't look too bad. You should see mine! Maybe it's the angle but judging by the spreaders and the lowermost batten in the picture it almost looks like your boom is hooked to windward a bit. Peter H23 "Raven"
But looking at the draft higher up I'd have to say your sail doesn't look too bad. You should see mine! Maybe it's the angle but judging by the spreaders and the lowermost batten in the picture it almost looks like your boom is hooked to windward a bit. Peter H23 "Raven"
Mates: If you are a beginner to intermediate from a sail trim stand point, take a look at the message Peter Suah wrote. What caught my attention was where he said the sail trim he was deliberately setting was with a specic purpose in mind. I'm sure Peter will agree with me when I say that when I first got to the point where I could adjust my sails with a purpose in mind I knew I had arrived. After that point in time, the lights went on and sail trim became the snap it actually is. A lot of mates look at their sails and they sense something is wrong but they have no idea what action to take to correct the situation. Because they are unsure what controls to use they sometimes use the wrong ones and make the matter even worse. I conduct "on the water" sessions, which last 4 hours, and the last part of the sesssions involves the participants critiquing other boats sail trim around us. It amazes me how good they get at determing the problem and telling me what corrective action is needed and what sail trim controls they need to push or pull to get the result they are looking for. Flip through any sailing magazine and look at the sail trim shown in the advertisements. Most of the pictures are photographically pleasing but can be improved. You've "ARRIVED" from a sail trim standpoint when you can look at the picture and know exactly what controls you'd use to correct the situation.
Scott of Seattle: I took a look at your picture and while another angle would be helpful, I really don't see anything wrong with the sail. I think it would be easy to flatten that sail. What do you think is wrong with the sail? Do you have a Boom Vang?
Don,
I feel fairly comfortable with my ability to use the sail trim basic to set for a purpose. It seems intuitive if you consider the airflow over the sail surface. But in spite of that, I'm having a little trouble getting a handle on leechline adjustments. Just can't seem to figure out what is being done. Any insights you (or anyone else) could share?
I feel fairly comfortable with my ability to use the sail trim basic to set for a purpose. It seems intuitive if you consider the airflow over the sail surface. But in spite of that, I'm having a little trouble getting a handle on leechline adjustments. Just can't seem to figure out what is being done. Any insights you (or anyone else) could share?
Bill: The main purpose of the leech line in the main and jib is to keep the leech from fluttering or "motor boating". When sailing upwind, you should tighten the leech cord JUST ENOUGH to stop it from fluttering. When reaching and running, the leech line is used to bend the battens, which give the mainsail more camber (shape/depth). What is actually happening is that by tightening the leech cord, you are preventing the top batten from twisting off since the leech cord is holding the batten in line with the boom. Most mates just crank on the leech line to stop the fluttering without realizing it can be used as a precise sail trim control. They are losing a small amout of potential speed in the process. Next time your out sailing mess with the leechline and watch what I'm talking about actually happen.
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