I recently had my mainsail hang up when I was trying to unfurl it from its inmast furl position. With someone else's help, the mailsail was taken down, put back up, and refurled, thus ending the problem. The person who helped pointed out that the problem might have been caused because the mast has "prebend"...a term with which I was unfamiliar. He pointed out that the mast has a bend toward the stern about 3/4th's the way up...not a great bend but nonetheless noticeable. Does anyone know what causes it and how it is remedied? Thanks for any help.
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Prebend
Means that the mast is purposely bent backwards by adjusting the shrouds to properly fit the luff curve of your main. Most mains have a luff curve built in by the loft. I am completely unaware of what they do with furling mains, but I'm sure that sailmaker can answer that question. Failure to bend the mast to match your main will greatly affect the shape and therefore the sailing ability.
Means that the mast is purposely bent backwards by adjusting the shrouds to properly fit the luff curve of your main. Most mains have a luff curve built in by the loft. I am completely unaware of what they do with furling mains, but I'm sure that sailmaker can answer that question. Failure to bend the mast to match your main will greatly affect the shape and therefore the sailing ability.
Alan, living in a marina full of Hunters with in
mast furling - none appear to have mast pre-bend. I would think the observation made is correct - pre bend will give furling problems if the bend is left in while furling the main.
mast furling - none appear to have mast pre-bend. I would think the observation made is correct - pre bend will give furling problems if the bend is left in while furling the main.
Another B&R rig mystery (of mine) solved.
I was going to post that question a couple of weeks ago but chickened out. It's logical though. The pre-bend on a conventional B&R main is to properly tune it. Of course, with no battens or roach, it can't be tuned so why bother?
OK, come on, anybody,,,? Nobody? I know about those new Selden vertical battens. Somebody must want to rattle my cage over those.
I was going to post that question a couple of weeks ago but chickened out. It's logical though. The pre-bend on a conventional B&R main is to properly tune it. Of course, with no battens or roach, it can't be tuned so why bother?
OK, come on, anybody,,,? Nobody? I know about those new Selden vertical battens. Somebody must want to rattle my cage over those.Sounds like your stuck.... *sry
..with a rig that will never be able to be properly tuned. I have to wonder if a roller furling main is worth not being able to get the right sail shape. I certainly would not judge my rig based on what other boats have or have not done. Most people that buy these boats have no clew (no pun) as to what a good rig tuning is. I would want to know from Hunter how to bend the mast with roller furling. But I think you should have asked these questions BEFORE you bought the boat.
..with a rig that will never be able to be properly tuned. I have to wonder if a roller furling main is worth not being able to get the right sail shape. I certainly would not judge my rig based on what other boats have or have not done. Most people that buy these boats have no clew (no pun) as to what a good rig tuning is. I would want to know from Hunter how to bend the mast with roller furling. But I think you should have asked these questions BEFORE you bought the boat.
inmast furling prebend
according to Hunter-read the manual! the inmast furling mast has less prebend than the conventional mast-only about 2" vs 6" but it should be there to properly shape the sail-the sail luff curve should have been built to match. If the mast wasn't set up properly, ie too much prebend, it's easy to see how it could cause jamming. The name is simple-the stays are set up to induce the bend in a static state, no sail or vang loads-it's often done while the mast is on the ground
according to Hunter-read the manual! the inmast furling mast has less prebend than the conventional mast-only about 2" vs 6" but it should be there to properly shape the sail-the sail luff curve should have been built to match. If the mast wasn't set up properly, ie too much prebend, it's easy to see how it could cause jamming. The name is simple-the stays are set up to induce the bend in a static state, no sail or vang loads-it's often done while the mast is on the ground
Then I've got one for Hunter *o
If you can't bend the mast anymore than the static 2" of prebend, how the hell are you supposed to flatten the main when the wind pipes up?? Outhaul will flatten the lower 1/3 of the main, what about the top 2/3 where you really need it??
If you can't bend the mast anymore than the static 2" of prebend, how the hell are you supposed to flatten the main when the wind pipes up?? Outhaul will flatten the lower 1/3 of the main, what about the top 2/3 where you really need it??
Forget Sail Shape
That is easily dealt with. The real problem is that the B&R rig has much less integrity unless the mast has pre-bend. It has no inner forestay so the rig relies on the mast straining against its own pre-bend to prevent the weight of wind in the top third of the mainsail causing the mast to invert when running. The aft swept spreaders help enormously - provided their roots are strong enough, but the lower shrouds are constantly pulling the mid section aft.
That is easily dealt with. The real problem is that the B&R rig has much less integrity unless the mast has pre-bend. It has no inner forestay so the rig relies on the mast straining against its own pre-bend to prevent the weight of wind in the top third of the mainsail causing the mast to invert when running. The aft swept spreaders help enormously - provided their roots are strong enough, but the lower shrouds are constantly pulling the mid section aft.
Alan, here is how I do it.....
While it has taken a few years to get use to, the roller furling main is a good sail. To flatten it at any time (meaning whether it is fully extended or partially furled) you use the furling line to get the shape you want. Don't touch the outhaul, but still crank on the furling line. I have a Hunter 380 and it took me some time to realize that the furling line could be used. It was sitting there in front of me but I never thought about it. I also use the boom vang to tighten the top of the sail if necessary, but I've been happy with the furling line.
While it has taken a few years to get use to, the roller furling main is a good sail. To flatten it at any time (meaning whether it is fully extended or partially furled) you use the furling line to get the shape you want. Don't touch the outhaul, but still crank on the furling line. I have a Hunter 380 and it took me some time to realize that the furling line could be used. It was sitting there in front of me but I never thought about it. I also use the boom vang to tighten the top of the sail if necessary, but I've been happy with the furling line.
Final word...
Selden Mast is actually the manufacturer of the mast. Amazingly enough, checking their web site, the actually have instructions on how to tune thier main furling mast (see link). What a concept! They have a wealth of information on other things as well, so I suggest that you browse a little bit to find other answers to question you might not even thought of to ask. Steve
Selden Mast is actually the manufacturer of the mast. Amazingly enough, checking their web site, the actually have instructions on how to tune thier main furling mast (see link). What a concept! They have a wealth of information on other things as well, so I suggest that you browse a little bit to find other answers to question you might not even thought of to ask. Steve
Jim, I tried to send you an email reply to your
question, but it gets rejected. Try using the link on my web site and we'll do it again.
question, but it gets rejected. Try using the link on my web site and we'll do it again.
Hey, Les
I've been thinking about your furling line method of flattening the main. It acts as an outhaul in reverse. This means that you can indeed flatten the foot of the main, but that will not change the draft of the upper part of the sail. Mast bending is the only way to accomplish that. Don't get me wrong. I'm not saying that the main is the problem. The problem is that you have no way to reshape the main for varying wind conditions. In winds up to about 20kts this will simply mean that the main is a little too full. No big deal for a heavy boat, but as wind strength increases beyond that the boat is going to become a handful to manage. Furling the main will indeed shorten sail area, but sail shape is still going to be poor.
I've been thinking about your furling line method of flattening the main. It acts as an outhaul in reverse. This means that you can indeed flatten the foot of the main, but that will not change the draft of the upper part of the sail. Mast bending is the only way to accomplish that. Don't get me wrong. I'm not saying that the main is the problem. The problem is that you have no way to reshape the main for varying wind conditions. In winds up to about 20kts this will simply mean that the main is a little too full. No big deal for a heavy boat, but as wind strength increases beyond that the boat is going to become a handful to manage. Furling the main will indeed shorten sail area, but sail shape is still going to be poor.
Well, you're correct, but then...
Alan, I hear (?) what you are saying but it does seem to flatten the sail some. I went down to the boat today and looked up my mast and there is a slight bend in it--how much I can't say, but I seem to remember Brion Toss saying a slight bend will help (He tuned my mast). Maybe that is what is happening. But I repeat, it does not seem to be much of a bend. I'm not a sail maker so take my comments with grain of salt, but wouldn't the belly of the sail be somewhat forward toward the luff on our boats? Therefore when you furl in the sail, it takes up on the belly and leaves you the flat part. Am I making any sense here? Damn, now I have to go down and try this out. But for the last couple of years, I have been using the furling lines to flatten the main sail. For a number of years I did heavy duty racing and we had a hydrolic backstay adjuster. We raced with a Ranger 32 and we could really flatten the main. But we also found out we were pulling the ends of the boat up about two inches (fore ad aft) which may account why the head door would not close when the backstay adjuster was on. The more I thought about that, the less I began to use the backstay adjuster. Later on when I had a Hunter 35.5 (which incidentally, we won boat of the year locally in racing), we quit using a back stay adjuster and begain to use a cunningham line that went back to the cockpit. It doesn't work as well but does flatten the sail somewhat. Aside from having the perfect sail or the perfectly smooth bottom paint, there is always the reality that I will make the wrong tack as a skipper in a race and the damn sail shape wouldn't count anyway. Go figures.
Alan, I hear (?) what you are saying but it does seem to flatten the sail some. I went down to the boat today and looked up my mast and there is a slight bend in it--how much I can't say, but I seem to remember Brion Toss saying a slight bend will help (He tuned my mast). Maybe that is what is happening. But I repeat, it does not seem to be much of a bend. I'm not a sail maker so take my comments with grain of salt, but wouldn't the belly of the sail be somewhat forward toward the luff on our boats? Therefore when you furl in the sail, it takes up on the belly and leaves you the flat part. Am I making any sense here? Damn, now I have to go down and try this out. But for the last couple of years, I have been using the furling lines to flatten the main sail. For a number of years I did heavy duty racing and we had a hydrolic backstay adjuster. We raced with a Ranger 32 and we could really flatten the main. But we also found out we were pulling the ends of the boat up about two inches (fore ad aft) which may account why the head door would not close when the backstay adjuster was on. The more I thought about that, the less I began to use the backstay adjuster. Later on when I had a Hunter 35.5 (which incidentally, we won boat of the year locally in racing), we quit using a back stay adjuster and begain to use a cunningham line that went back to the cockpit. It doesn't work as well but does flatten the sail somewhat. Aside from having the perfect sail or the perfectly smooth bottom paint, there is always the reality that I will make the wrong tack as a skipper in a race and the damn sail shape wouldn't count anyway. Go figures.
There's a difference ...
..between draft position and draft depth. The former is adjusted with cunningham, halyard tension. This is the distance back along the curve of the main where the greatest depth occurs. The amount of draft (or depth) in the curve of the main is controled by mast bend. The more the mast is bent the less draft the main has. Certainly there is a limit to how much backstay to put in. If you are deforming the shape of the hull, then I think you've gone a bit too far. I'm not trying to beat a dead horse here, but trying to understand how Hunter could produce a rig that basically can't be adjusted properly. And it's not just Hunter, but all boats that use in-mast furling.
..between draft position and draft depth. The former is adjusted with cunningham, halyard tension. This is the distance back along the curve of the main where the greatest depth occurs. The amount of draft (or depth) in the curve of the main is controled by mast bend. The more the mast is bent the less draft the main has. Certainly there is a limit to how much backstay to put in. If you are deforming the shape of the hull, then I think you've gone a bit too far. I'm not trying to beat a dead horse here, but trying to understand how Hunter could produce a rig that basically can't be adjusted properly. And it's not just Hunter, but all boats that use in-mast furling.
Alan, you're starting with the wrong assumption..
By far not all sailboats without in-mast furling use adjustable mast bend as a tool to depower or power up the main. Many of the larger cruising vessels with sturdy rigs can't use this tool because the forces needed would be unacceptably large, thereby increasing the chances of rig failure and/or deck/hull structure deformation (fore-and-aft hogging). Moreover, the fractional B&R rig with pre-bend mast on our own Legend 43 is also not set up to allow increased mast bend. Although the ability to increase or decrease mast bend is unquestionably useful and handy there would appear to be nothing inherently indispensible about it. IMHO, it is just one of a handful of tools for powering up or powering down the main. Have fun! Flying Dutchman
By far not all sailboats without in-mast furling use adjustable mast bend as a tool to depower or power up the main. Many of the larger cruising vessels with sturdy rigs can't use this tool because the forces needed would be unacceptably large, thereby increasing the chances of rig failure and/or deck/hull structure deformation (fore-and-aft hogging). Moreover, the fractional B&R rig with pre-bend mast on our own Legend 43 is also not set up to allow increased mast bend. Although the ability to increase or decrease mast bend is unquestionably useful and handy there would appear to be nothing inherently indispensible about it. IMHO, it is just one of a handful of tools for powering up or powering down the main. Have fun! Flying Dutchman
Pre Bend
Guy's it's a prebent mast with cabling set up that's doesn't allow you to adjust the bend by back stay adjustment. Look at what happens to the inner diamond cables when you tighten the back stay they pull against you preventing any more bending of the mast. Basically all the back stay adjuster does on a B&R rig is tighten the forstay helping head sail control. That's why one of the boats was having problems with the head door and pulling up on bow & stern. You have 2 controls to really help flaten and maintain main sail shape on this rig. Cunningham & Boom Vang. need more belly put on Cunningham. For a flater sail release Cunningham, increase down word Vang pressure. With these 2 controls you can control the depth and postion of belly of the main. Sure there other controls available but I'm telling these are your basic 2 for main sail control. I could tell you the others but I'm a real slow typiest and terrible speller. There are some VCR tapes out there that explain all of this in heavy weather sailing. Can't remember the name now mine is under snow and 22 degress. See Ya
Guy's it's a prebent mast with cabling set up that's doesn't allow you to adjust the bend by back stay adjustment. Look at what happens to the inner diamond cables when you tighten the back stay they pull against you preventing any more bending of the mast. Basically all the back stay adjuster does on a B&R rig is tighten the forstay helping head sail control. That's why one of the boats was having problems with the head door and pulling up on bow & stern. You have 2 controls to really help flaten and maintain main sail shape on this rig. Cunningham & Boom Vang. need more belly put on Cunningham. For a flater sail release Cunningham, increase down word Vang pressure. With these 2 controls you can control the depth and postion of belly of the main. Sure there other controls available but I'm telling these are your basic 2 for main sail control. I could tell you the others but I'm a real slow typiest and terrible speller. There are some VCR tapes out there that explain all of this in heavy weather sailing. Can't remember the name now mine is under snow and 22 degress. See Ya
rattling Fred's cage?
First of all, backstay tension is about shaping the foresail, not the main. The backstay affects depth in the middle and upper genoa sections by controlling luff sag. To a lesser extent, backstay tension affects twist. Second, it's possible to have both battens and roach in a furling main. My main is a full-battened tri-radial laminate with vertical carbon-fiber battens. The shape is incredible, and it flattens itself automatically when I reef it because it reefs toward the clew, not the head, meaning that I reef toward the flatter part of the sail, unlike conventional systems where reefing doesn't affect draft. (This, by the way, is why Les can claim to flatten the sail more effectively with the inhaul than the outhaul.) I can go from full sail to quadruple reef in about twelve seconds without ever leaving the cockpit, and without expending any more energy than it takes to roll up my jib. I don't really need a cunningham because I use the batten pockets as reef points, which means that the sail adjusts for luff tension internally. With vertical battens it's vitally important to minimize pre-bend, but this factor is designed into the sail shape in accordance with the initial specs. The only thing I lose from this setup is the ability to control jib sag, but I didn't have that ability to begin with thanks to the B&R rig. From my perspective that's a fair trade-off, because very few cruising boats have that ability anyway. The boat I used to race had a hydraulic backstay tensioner and running backstays. Don't miss them at all.
First of all, backstay tension is about shaping the foresail, not the main. The backstay affects depth in the middle and upper genoa sections by controlling luff sag. To a lesser extent, backstay tension affects twist. Second, it's possible to have both battens and roach in a furling main. My main is a full-battened tri-radial laminate with vertical carbon-fiber battens. The shape is incredible, and it flattens itself automatically when I reef it because it reefs toward the clew, not the head, meaning that I reef toward the flatter part of the sail, unlike conventional systems where reefing doesn't affect draft. (This, by the way, is why Les can claim to flatten the sail more effectively with the inhaul than the outhaul.) I can go from full sail to quadruple reef in about twelve seconds without ever leaving the cockpit, and without expending any more energy than it takes to roll up my jib. I don't really need a cunningham because I use the batten pockets as reef points, which means that the sail adjusts for luff tension internally. With vertical battens it's vitally important to minimize pre-bend, but this factor is designed into the sail shape in accordance with the initial specs. The only thing I lose from this setup is the ability to control jib sag, but I didn't have that ability to begin with thanks to the B&R rig. From my perspective that's a fair trade-off, because very few cruising boats have that ability anyway. The boat I used to race had a hydraulic backstay tensioner and running backstays. Don't miss them at all.
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