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#1
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how to modify mainsail to raise boom
In my advancing age, I have developed a sensitivity to the sun.
Therefore I am installing a bimini on my Sea Sprite 23. I purchased a stock bimini and modified it so that it doesn't interfere with the sheets or winches. Now I need to raise the boom about six inches to get a couple of inches of clearance. I asked two sailmakers and got two completely different answers on how to do this. One sailmaker said that I should cut the six inches off the foot. He said modifying the head usually results in many problems, mainly interference with the backstay. However, to me, it looks as though it shouldn't interfere. The masthead assembly appears to keep the backstay far enough from the sail. I can't get an exact measurement though, since the mast is raised. Another sailmaker said that I should modify the head to get the six inches. My current mainsail has a headboard with a top width of 4 1/2". He says that he will use the same headboard and re-taper the leach of the sail from the top batten to headboard. The sail has four standard battens. Could you please give me your opinion on this? How would shortening the head and raising the sail effect how the boat sails and its stability? This method would of course mean losing much less sail area. I use the boat mostly for coastal crusing. |
#2
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I'd start with no modifying at all and hoist the sail with a "loose
bottom". In other words you don't shove the foot in the boom but you only attach the bottom with the front eye to the reef-hook using a 4"of strong line and the the rear opening of the bottom end in the normal way (sorry, English is not my native language). That way you can hoist the sail a bit higher (assuming you have sufficient room at the top of the mast. As a consequence the boom will raise 4"at the spot you want it to for your bimini. I do this for practically the same reason as you described and I'm very happy with the shape of the sail. On 9 Aug 2005 11:48:19 -0700, wrote: Now I need to raise the boom about six inches to get a couple of inches of clearance. ----------------snip Could you please give me your opinion on this? How would shortening the head and raising the sail effect how the boat sails and its stability? This method would of course mean losing much less sail area. |
#3
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Thanks Len,
But I already moved the front of the boom higher so that the sail now goes to the top of the mast. I still need six more inches so that I am a couple of inches above the bimini. John |
#5
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In that case it depends on how balanced you're now with a full rig at
say 5 bft. When you've got a bit of weather helm now, you'll probably improve the balance (and thus the speed) when you take away sail at the bottom... If you are happily belanced now I'd choose to modify the top of the sail, it's less loss of sail-surface. And probably cheaper than modifying the lenghthy bottom.... Only thing is how does the sailmaker make sure there'll be a adequate extension of the top part of the sail, maybe an extra stiffener on the right spot to avoid "flapping around" of the first yard(s) from the top ? Regards, Len. On 9 Aug 2005 16:10:56 -0700, wrote: But I already moved the front of the boom higher so that the sail now goes to the top of the mast. I still need six more inches so that I am a couple of inches above the bimini. |
#6
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Jere,
I don't understand how using the topping lift can get me more clearance. I've always assumed that the topping lift should be completely slack when sailing. Otherwise, wouldn't it adversely effect the sail shape. Also, it seems that the thin topping line would eventually break when the mainsheet is pulled down hard enough. John |
#7
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The most cost effective and efficient way to raise the boom is to cut it off
of the head. The amount of labor will quadruple if you cut it off of the foot. Remove the six inches put the same headboard back on and re-fair it to the top batten. In some extreme cases the angle at the top batten is too severe and your sailmaker will need to fair it down to the second batten. Andrew Scott www.scottsails.com wrote in message oups.com... In my advancing age, I have developed a sensitivity to the sun. Therefore I am installing a bimini on my Sea Sprite 23. I purchased a stock bimini and modified it so that it doesn't interfere with the sheets or winches. Now I need to raise the boom about six inches to get a couple of inches of clearance. I asked two sailmakers and got two completely different answers on how to do this. One sailmaker said that I should cut the six inches off the foot. He said modifying the head usually results in many problems, mainly interference with the backstay. However, to me, it looks as though it shouldn't interfere. The masthead assembly appears to keep the backstay far enough from the sail. I can't get an exact measurement though, since the mast is raised. Another sailmaker said that I should modify the head to get the six inches. My current mainsail has a headboard with a top width of 4 1/2". He says that he will use the same headboard and re-taper the leach of the sail from the top batten to headboard. The sail has four standard battens. Could you please give me your opinion on this? How would shortening the head and raising the sail effect how the boat sails and its stability? This method would of course mean losing much less sail area. I use the boat mostly for coastal crusing. |
#8
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In article .com,
wrote: Jere, I don't understand how using the topping lift can get me more clearance. I've always assumed that the topping lift should be completely slack when sailing. Otherwise, wouldn't it adversely effect the sail shape. Also, it seems that the thin topping line would eventually break when the mainsheet is pulled down hard enough. John In light-air conditions, I will tension the topping lift to introduce twist. Xan's boom is so heavy that I have to do it fairly regularly. What I forgot to mention is that most boats' booms are lifted off the topping lift when properly hoisted. Thus, it may be that the original poster need not change his sail at all; just support it a bit higher when the sail's furled. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
#9
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Oops, I posted this message yesterday as a new topic by mistake:
Thanks to everyone for your advice. I had the sail altered by cutting the six inches off of the head. The boat was sailing very well before. After I try the altered sail out, I will report back on this thread about what effect it had. It might not be for a week or so though. Thanks John |
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