Don ... I have an old main (sailing a C27) that I can't afford to replace right now. On the wind in upwards of 10 knots, I set it for: good halyard tension sheet tensioned to place the top batten parallel to the boom traveler positioning the boom at center line Set up that way, all three of my leech telltails are streaming correctly. That's my understanding of the "book" on setting up your main. Here's the problem. I've pulled the mast forward till it's standing straight up, but I'm still getting too much weather helm as heal goes to 15 degrees or more. I'm thinking the culprit is the blown out main, which has its center of effort too far toward the leech cause it's bellied up too much. Any other suggestions? Tom
compensating for an old main
- Thread starter Tom Monroe
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Tom
You could very well be correct about needing a new main. Check the draft location. If it is more than 50% then you could increase halyard/cunningham tension to try and pull it further forward. Weather helm is also created by a dirty bottom and high drag props like a fixed 3 blade. You could also try easing the traveler down a little and increasing sheet and vang tension. This will certainly cost you some speed but will also ease some of the weather helm. Here is where a fractional rig with a backstay adjuster becomes a great asset. Bending the mast helps to flatten the main de-powering it and relieving weather helm. Unfortunately your mast is built more like a telephone pole and would be near impossible to bend.
You could very well be correct about needing a new main. Check the draft location. If it is more than 50% then you could increase halyard/cunningham tension to try and pull it further forward. Weather helm is also created by a dirty bottom and high drag props like a fixed 3 blade. You could also try easing the traveler down a little and increasing sheet and vang tension. This will certainly cost you some speed but will also ease some of the weather helm. Here is where a fractional rig with a backstay adjuster becomes a great asset. Bending the mast helps to flatten the main de-powering it and relieving weather helm. Unfortunately your mast is built more like a telephone pole and would be near impossible to bend.
Old Main
Tom: As you can imagine it is hard to determine the cause of a problem by reading a short narrative but lets give it a go. There are 2 parts to deal with in your situation. One is the weather helm problem and the other is the heeling problem. Lets deal with the weather helm situation and hope this might solve your heeling problem. First, I don't think the problem is with the mainsail. Before I go on, it might be a good idea to have a sail maker look at your mainsail. With a little "nip and tuck" you might get a few more years out of it. I thought the mainsail on my C30 was shot and took it to a local sail maker who fixed it up for under $150 dollars. He could have sold me a new one with my mind set so look for an honest guy. I had a weather helm problem when I first bought the C30 and had no idea what the previous owner had done. I started with mast alighment and lined up the mast to straight up and down. I still had a weather helm problem. Finally I had a rigger check it out. Guess what - it was not as straight as I thought it was. Mast rake will increase weather helm because you are moving the mast aft on the deck and changing the center of effort. About 1/2" of rake on a 40' luff can change the shape of the sail. Rake effects sail shape and sail shape effect weather helm. Sort of a vicious circle. A tight leech can be another part of the problem because a tight leech with no twist turns the wind more. This turning effort is similiar to turning the rudder. Turning the rudder = weather helm. You did not indicate how much weather helm you were experiencing. You can calculate it by placing a piece of tape on your wheel when the rudder is centered. 7 degrees of weather helm can be acceptable but when you approach 10 degrees something is wrong. The rudder is creating too much drag. On a reach some weather helm is acceptable but on a run you want zero weather helm. Getting the mast straight is not the whole story. Helm is very important. At about 5 knots of wind you should start to feel WH. If you take your hand off the wheel or tiller the boat should start to react. At 10 to 12 knots you should need about 3 to 5 degrees of helm to make the boat go straight. At 14 to 15 knots you would need about 5 degress of helm to make the boat go straight. These setting are normal and indicate your getting the proper amount of lift from your rudder. Anything beyond that indicates a problem. Before tearning the mast apart, try this the next time your out sailing. You can decrease WH by increasing mainsail twist and by moving the fairleads aft and/or easing the mainsheet and jib shet. If it were me I'd start with the mast. Additionally, could you tell me how much WH (not heel) you are experiencing?
Tom: As you can imagine it is hard to determine the cause of a problem by reading a short narrative but lets give it a go. There are 2 parts to deal with in your situation. One is the weather helm problem and the other is the heeling problem. Lets deal with the weather helm situation and hope this might solve your heeling problem. First, I don't think the problem is with the mainsail. Before I go on, it might be a good idea to have a sail maker look at your mainsail. With a little "nip and tuck" you might get a few more years out of it. I thought the mainsail on my C30 was shot and took it to a local sail maker who fixed it up for under $150 dollars. He could have sold me a new one with my mind set so look for an honest guy. I had a weather helm problem when I first bought the C30 and had no idea what the previous owner had done. I started with mast alighment and lined up the mast to straight up and down. I still had a weather helm problem. Finally I had a rigger check it out. Guess what - it was not as straight as I thought it was. Mast rake will increase weather helm because you are moving the mast aft on the deck and changing the center of effort. About 1/2" of rake on a 40' luff can change the shape of the sail. Rake effects sail shape and sail shape effect weather helm. Sort of a vicious circle. A tight leech can be another part of the problem because a tight leech with no twist turns the wind more. This turning effort is similiar to turning the rudder. Turning the rudder = weather helm. You did not indicate how much weather helm you were experiencing. You can calculate it by placing a piece of tape on your wheel when the rudder is centered. 7 degrees of weather helm can be acceptable but when you approach 10 degrees something is wrong. The rudder is creating too much drag. On a reach some weather helm is acceptable but on a run you want zero weather helm. Getting the mast straight is not the whole story. Helm is very important. At about 5 knots of wind you should start to feel WH. If you take your hand off the wheel or tiller the boat should start to react. At 10 to 12 knots you should need about 3 to 5 degrees of helm to make the boat go straight. At 14 to 15 knots you would need about 5 degress of helm to make the boat go straight. These setting are normal and indicate your getting the proper amount of lift from your rudder. Anything beyond that indicates a problem. Before tearning the mast apart, try this the next time your out sailing. You can decrease WH by increasing mainsail twist and by moving the fairleads aft and/or easing the mainsheet and jib shet. If it were me I'd start with the mast. Additionally, could you tell me how much WH (not heel) you are experiencing?
Weather helm
You are probably correct in your assumption that the draft in your old main is too far aft. This will certainly induce excessive weather helm. If you are able to get the top batten parallel to the boom with this old sail, I wouldn't be surprised if the sail is over trimmed with excessive depth for the prevailing wind conditions. If after you try putting more halyard or cunningham tension on the luff and you still can't get the draft to move forward, try taking a reef in the main. The reduction of sail area will not hurt you nearly as much as too much weather helm.
You are probably correct in your assumption that the draft in your old main is too far aft. This will certainly induce excessive weather helm. If you are able to get the top batten parallel to the boom with this old sail, I wouldn't be surprised if the sail is over trimmed with excessive depth for the prevailing wind conditions. If after you try putting more halyard or cunningham tension on the luff and you still can't get the draft to move forward, try taking a reef in the main. The reduction of sail area will not hurt you nearly as much as too much weather helm.
Outhaul?
Tom - You say the draft depth is too much but don't mention the outhaul. Is it tight as can be and still "bellied up too much"? Rick
Tom - You say the draft depth is too much but don't mention the outhaul. Is it tight as can be and still "bellied up too much"? Rick
Tight Leech
I know that my mainsail has a tight leech - it's the first thing that gets tight when I sheet, before the main is ANYWHERE near flat. I think I may try cutting the leech reinforcement and adding a little bit to it..tired of ol' baggysail!
I know that my mainsail has a tight leech - it's the first thing that gets tight when I sheet, before the main is ANYWHERE near flat. I think I may try cutting the leech reinforcement and adding a little bit to it..tired of ol' baggysail!
I tried everything ...
... in 15 knots of wind this past weekend, with a new 135 up in the front. Bottom line is the main just won't set at all anymore. Reefing will stand the boat up, but doesn't change the fact that the main is just not contributing to boat speed anymore. At one point, I checked boat speed with it up, reefed, and doused all the way. 0.1 knots of difference. Since it is a twenty year old sail, I'm not going to have it re-cut. Maybe the sailing fairy will drop $1000 on me during the offseason with which to buy a new one. Otherwise, I guess I just live with it. Tom
... in 15 knots of wind this past weekend, with a new 135 up in the front. Bottom line is the main just won't set at all anymore. Reefing will stand the boat up, but doesn't change the fact that the main is just not contributing to boat speed anymore. At one point, I checked boat speed with it up, reefed, and doused all the way. 0.1 knots of difference. Since it is a twenty year old sail, I'm not going to have it re-cut. Maybe the sailing fairy will drop $1000 on me during the offseason with which to buy a new one. Otherwise, I guess I just live with it. Tom
used sails
Have you looked at used sails?? Or "stock" sails?? I see Catalina 27 mains going for around $650-$700
Have you looked at used sails?? Or "stock" sails?? I see Catalina 27 mains going for around $650-$700
Tighten it up!
While my 23 year old main may not have seen what your main has, it still looks old. But it still works well and I think that's mostly from the tuning. Unless you are bucking heavy seas tighten it up and flatten it out. Especially the cunningham/halyard to pull the draft forward. If you really have aft streaming leech telltales you are pretty close. Put some in the middle of the sail to see if you are OK. The main is pretty stall resistant with a genoa but make sure you aren't closing the slot too much. Try sailing with just the main sometime, with my h27 that was really enlightening and told me the sail was fine. I'm not sure where Don gets his scoop but rake won't affect the sailshape--it will certainly change the center of effort position and that affects the weather helm but not the shape. Hope you don't have to buy new sails... Cheers, Hugh
While my 23 year old main may not have seen what your main has, it still looks old. But it still works well and I think that's mostly from the tuning. Unless you are bucking heavy seas tighten it up and flatten it out. Especially the cunningham/halyard to pull the draft forward. If you really have aft streaming leech telltales you are pretty close. Put some in the middle of the sail to see if you are OK. The main is pretty stall resistant with a genoa but make sure you aren't closing the slot too much. Try sailing with just the main sometime, with my h27 that was really enlightening and told me the sail was fine. I'm not sure where Don gets his scoop but rake won't affect the sailshape--it will certainly change the center of effort position and that affects the weather helm but not the shape. Hope you don't have to buy new sails... Cheers, Hugh
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