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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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Old 12-26-2001
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recutting my blown out main

The shape of my 20 year old main is a bit blown out. The draft is far forward and the boat sails a bit better with a reef in, due to the better shape. A new (Or used) sail is not in the cards right now. I am going to try to recut the main along the foot of the sail. My best guess is to draw a chalk line on the sail while raised on the boom along where I think it should be taken in. I guess that I plan on taking in about the shape of an airfoil, deepest just aft of the mast and going shallow and the luff. Does anyone have any idea, recomendations, cautions or comments? I would be reusing the boltrope.
Fair winds,
Jollymonjeff
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Old 12-26-2001
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recutting my blown out main

mmmmmm Something doesn''t sound quite right here as normally with a dacron sail (I am supposing that the sail is dacron) with a *3 strand dacron bolt rope* usually over time develops into a draft-aft with more fullness configuration as the sail ages. What normally occurs is that the dacron bolt rope shrinks with age, not stretches. A stretched bolt rope results in a ''flatter'' sail and that doesnt seem like what you are posting. If you have the original dimensions of the sail, carefully measure the luff and foot to see in fact that the boltrope has changed dimensions. Normally, when constructing a new dacron sail, a boltrope is pre-set/pre-loaded with approximately 1" shortening for every 10-11ft. of luff or foot length.... meaning that sometimes you can recondition (somewhat) the shape and draft position by loosening/easing and repositioning (or replacing) a shrunken bolt-rope.
Many times a sail with a shrunken bolt rope will set ''OK'' if you use extreme halyard and outhaul tension. On my own sails, I used to readjust/replace the dacron boltropes every 2nd year.
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Old 12-26-2001
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recutting my blown out main

Jeez, Jeff. You are a brave man; especially if you can''t afford to replace the sail if you screw up. First of all, the maximum draft should be quite far forward. Normally as a sail ages, it is the leech that stretches and as it does the point of max camber migrates aft. Recuts rarely take anything out of the luff. They are normally broad seamed cuts (curving on one panel and not the other) that occur at several panel seams and extend from the leech of the sail going forward of the center of the sail. Doing a good recut takes quite a bit of skill and judgement to do well and avoid ending up with ''Frankensail''. A well executed recut is actually harder to figure out what to do than to design a whole new sail which in a good loft is done on a computer. My best suggestion is to befriend someone who works for a sailmaker and pick their brain.

Good luck
Jeff
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Old 12-27-2001
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recutting my blown out main

Ahoy jollymonjeff, poppycock and goofy haven''t a clue on this one, Holidays are over folks! I''ve got your answer because I''ve just done what you mentioned and your plan is sound. Your sail has pulled into the shape you see it as. I used a majic marker (red of course) and made my line along the boom as you suggest. I recut the sail removed the rope then very carefully hemmed the sailcoth , hand sewing it where I wanted it (keep in mind that the material has a mind of it''s own. Don''t fight it. Start by making several tack points and see how it lays out. (You''''ll need lots of open space to work in). After I had it hemmed flat all along the sail I then had a friendy machine operator sew it but good. Re-attaching the rope was a painfull and tedious process but not all that difficult. Keep the rope straight and watch it dosen''ty twist up and pull the lower edge of the sail out of shape.
Lastly I had to re-gromet for my slides and re-tie them on. My finished product corrected 90% of my problem and cost little except patience and about two thimbles of blood from needle pricks. Your not wrong to make your interium changes no matter what the" buy new , professional desiged " pundits say. From what you describe it can''t get any worse any way, mine didn''t. The chalk line didn''t work for me. I will admit that having a recut unprofessional sail on my boat my may make me a Pirate among the esteemed members of this site but you know what? ... shiver me resins I don''t care! Big Red 56
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Old 12-27-2001
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recutting my blown out main

A total a recut, especially with the original dimensions lost in time, is difficult at best. If you can send me a digital pic of the sail beating to windward @ 10-15kt., held near to the centerline and with normal mainsheet tension, etc. ... and the pic taken from directly under the boom (looking to the top of the mast) I''ll better be able to give a more precise suggestion on rebuilding. A temporarily placed draft stripe at mid section (halfway up using a removable masking tape etc.) would be of benefit. The maximum draft on a main (for a masthead rig) should be at mid-cord to 40% of mid cord from the luff; a too far forward draft location will get you nowhere. I completely disagree with BigRed as normally (again assuming a dacron sail with dacron 3 strand boltrope) the boltrope system doesnt have to be entirely replaced - many times you can simply slide the old rope from the sleeve and put in a new one with the proper normal preload and simply restitch the 3 connections with sail twine and a robust sail needle and awl. Leech sag (stretch) over time usually does NOT affect draft location. If the leech is stretched (tripped), sometimes you can ''get away'' with placing intermediate short lightweight battens between the present battens - otherwise its a simple process of reseaming the panels ends to correct for a leech that falls off to leeward. The real question that you have to ask yourself is: is the sail material too far degraded by UV that any adjustment will NOT be worth the effort, is the stitching UV destroyed and the sail need an entire restitching? Is the material degraded (weak), etc., for that case you probably will need a new sail.
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Old 12-27-2001
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recutting my blown out main

To all who have been kind enough to offer their help...I thank you. A request was made to see what the sail looks like. I appoligize that I did not think to take any pics that really show it well, but I do have some pics posted that can give you an idea. In the pics, the mainsail is what we are looking at. The Halyard is drawn taught as is the outhaul. The boom is sheeted at about 90 degrees to the mast using an endboom sheeting arrangement to a traveler. Keeping in mind that the boat is far from a racer to beginwith, I am just looking to make her sail a bit better. again, all opinions welcome.
http://communities.msn.com/BaylinerBuccaneerSloops/margaritaville285ccundersail.msnw
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Old 12-27-2001
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recutting my blown out main

Bucpic2.jpeg is the only one that shows much of the main. Its hard to analyse from a ''head on'' photo . But, from the ''girts'' (beginnings of creases) that run diagonally from the mast down towards the clew, suggests that there simply in not enough halyard tension (and perhaps too much outhaul tension). The mainsail also seems grossly overtrimmed and the wind seems exceptionaly light ---- so that may confuse what is actually going on in the pic. I also see that there are no tell-tales on the sails (luff and leech) ... and they would tremendously help in correctly setting and shaping a sail for the exact conditions at hand. My suggestion before you start recutting, etc. is to get a full set of telltales on each sail at the leech and luff (also do a websearch for "gentry-tufts") and then see if some heavy halyard tension in setting up the sails might greatly improve the situation; applying self adhesive draft stripes would also help. If you can find a copy of the "New - Best of Sail Trim", a paperback published by Sail Mag (about 1980) would be of benefit, especially the articles written by Arvel Gentry - probably one of the foremost aerodynamicists who did quite a lot of actual and theoretical sail analysis ... and then clearly wrote very elegant and simple articles for the sailing world.
From the age of the sail, the pic shown on the website either you need much more halyard (or cunningham) tension .... or need to ease the boltrope.
:-)
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