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Mast Tuning

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markreilly	Mast Tuning		Lead	[-]
Posts: 4 03/04/08 12:06:28	Tags : None Hey Guys, I've got a question for the racers. (this will get lengthy, sorry!) Headstay sag! I hate it. We have a 2001, 3-cabin pullman, In-mast furling, wing, Charleston Spar. Please, don't anybody tell me to tighten the backstay. Here's what I do know. She won't point at 30 degrees with a wing keel. (fine, but 45 would be nice) You need rake to point, (because of center of force physics) you can't bend a furling mast too much and expect the main to roll up easily, and swept spreaders are designed to keep pre-bend in the mast. O.K. here's the question. what have any of the racers done to tune their rig to handle a 15kt blow and not have the headstay bow out 12-15 inches? Yes, my sails are 2001 originals and a little 'baggy'. I've had 'The Rigger' try to tune her and he shortened the headstay 2" (in the turnbuckles) which gave me the wrong rake, bent the hull so bad I couldn't close my cabin door, and the boat went backwards (so to speak) I've tightened the shrouds before to 25% but still had my dreaded sag. It seems like the mast just wants to 'crush' down instead of tighten the headstay. I'm thinking of tightening the lowers to 'max' and just enough on the intermed. and cap shrouds to keep in-column. Oh yah, the off-set backstay makes it interesting to keep her staight. ( I can't get to this often but I'll try.) Mark, Bella Luna
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nickwigen	If I can't tell you to tighten the backstay I can't help you.	#1	[url]	[-]
Posts: 221 03/04/08 15:48:24	12-15" of sag is incredible. With the rail down in 18-20 kts (135% genoa) I see about 6" sag. Mast bend won't effect the sag in the headstay, it only effects the draft in the main. If you are going to straighten the headstay the only real choice is to tighten the backstay. I run ours with the shrouds adjusted so they leeward side is only slight snug with the rail at the water's edge. Repeated tacks are done to make the adjustments underway so the leeward side shrouds are the same and the mast is straight. Then tighten the backstay until the headstay has the 6" sag when hard to weather. You will have only a bit of effect on headstay tension with the upper shrouds, none with the lowers. The previous owner installed a hydraulic backstay adjuster that has limited use on our boat. I do run the backstay a bit slack at the dock but when sailing we crank it up to where it should be. I don't look at as a way of tightening the backstay but more as a way of loosening it when we are not sailing. If we bought another 42 I wouldn't bother with the adjustment. A couple of things I've found: After 22° heel it's time to reef. Our 1990 fin keel sails best with the mast a bit forward. It actually has a slight negative rake. Before making this change the weather helm was more than I like. If you are using a tension gauge the port side upper will have more tension than the starboard due to the off-center backstay. We found this out once after a professional rigger tried to set up the shoud tension based on % of shoud strength. By the time he had them equal we had about 4" of bend in the mast. After he left I went back to the procedure above and it seems to work just fine. Nick Wigen Ursa Minor #178 FK, 3-Cabin Portland, Oregon
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tomca		#2	[url]	[-]
Posts: 80 03/04/08 17:11:33	Tuning the 42's rig is a matter of trial and error. I tried to tune the rig using a tension gauge and that ended up just tweaking the rig from one side to the other once the proper backstay tension was applied. It is amazing how the slight offset in the backstay can really mess up the overall rig tension. I am seriously looking at adding a second backstay using Spectra line to have a centered fully adjustable backstay that can be removed easily when cruising. I believe that some sag is inevitable but removing the majority of it requires backstay tension...centered. Tom Maxwell #766 2-cabin Pullman Dana Point, CA
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markreilly		#3	[url]	[-]
Posts: 4 03/05/08 13:02:47	Thanks for the tips. I do know that the cap shrouds don't tighten the headstay much. The problem I have with tightening the backstay is that it only seems to put more bend in the mast. (crush the mast) When I had 0-negative rake, she was scary! She had a BUNCH of Lee helm. Darn dangerous if you ask me. If I could get only 6" of sag at 15kts, she would point at 45 degrees with no problem. But with all that sag, the luff back-winds at 45 degrees. I have to drop off to 50 degrees just to keep her from luffing the headsail. I'm not concerned with mast bend and flattening my main, it's a small, no roach, no batten, nothing son-of-a-gun anyway. To me, the mast bend takes away my headstay tension. And the 42's are a headsail driven boat. Oh by the way, I did have my backstay at 28% and still had my sag. Mark
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yorkrose		#4	[url]	[-]
Posts: 275 03/05/08 14:07:28	Mark, You seem to be avoiding the obvious. A baggy headsail simply is going to give a lot more thrust in the wrong direction, namely, sideways. The leading edge airfoil shape is critical to getting lift in the forward direction rather than the sideways direction. There may be little that can be done to improve either the headstay sag or the pointing with that sail. I presume you are already cranking on extreme halyard tension. Regards, Gene Fuller Yorkshire Rose, C42 #870
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markreilly		#5	[url]	[-]
Posts: 4 03/05/08 15:08:19	I agree the baggy sail comment. Yes, I'm cranking the halyard after unrolling it. I do have a new headsail coming and am hoping for much better perfomance. I do agree that the sail can cause a lot of the sag because of the extra drag on the sail. I was just wondering if any one else had that much sag and mast bend. Oh, and to throw one more thing in, when I go up the mast (which I climb myself to keep the person on the winch quiet) the mast is awfully 'springy' like a pogo stick. I thought that was odd, I don't know. I guess when I watched a fellow racer's mast fold in half (a 380 tall rig) in 20-25kts during a 'cruiser race', I worry a little. Mark
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