Sail Shape

[WFK]

I'm having a heck of a time getting this ugly crease out of my sail.. I've tried adjusting the out hauls as well as slacking off on the peak in order to create a little more shape. Any thoughts would be appreciated.
Bill
http://www.imagestation.com/picture/sraid210/pa79993375aeae701eb5d7fd062041ac1/edd92cb7.jpg

[Tom Hunter]

Have you talked to your sail maker?

If you are the sail maker you might try loose footing it. I am not certain that would work but it might help.

[John B]

It needs more foot tension, probably more tension on the gaff( head) and a tightened peak halyard to pull those throat to clew lines out. Throat halyard/luff looks OK.
Looks like plenty of sail area you have there:)

Oh ( cue Hwyl), I can't quite see but that first gasket in from the clew looks under strain... that implies that you don't have a gasket/roband around the boom at the clew and you need one. If you do have one then the extra foot tension will straighten that out.

[almeyer]

when I set up my lug rig. At the advice of some folks on the forum, I set up a tack downhaul and moved the halyard attachment point back, which may not be applicable in your case. Worked fine.

Before:
http://www.imagestation.com/picture/sraid136/pff528ba578249d1aa67d797b34815d77/f74e6ff7.jpg

After:
http://www.imagestation.com/picture/sraid181/pd8ac7b32ef777a18450882e4355121ee/f2e8c2ea.jpg

[John B]

Which peaks the sail up a bit. ;)

she just looks so sweet doesn't she.

[WFK]

Thanks you guys. I'm excited to finally get a picture while under sail so I can sit back and really analyize this. I've put the robands on and it definatley helps, and if I take and physically pull the sail down and fwd. I can get the crease to dissappear, but John I'm not sure how extra foot tension will get rid of the strain at that gasket. It seems like it would make it worse. I'd think the same would apply up on the gaff..........I was beginning to wonder if the sail was just cut wrong......Thoughts?
Bill

[WFK]

almeyer...........Pretty boat. Since I'm dealing with a sliding gunter, I think it's a slightly different situation.
Isn't it a shame that work interferes with sailing time. Now I'm forced to wait until Saturday to mess around again. This weather has just been too nice and I was able to get in 8 or 10 hours of sailing over the weekend, so no complaints by me about this so called heat wave:rolleyes: . There'll be plenty of clouds and rain in no time around here!

Bill

[John B]

WFK, those lines throat to clew ,are caused because the angle made between the head and the luff is incorrect for the cut of the sail. The peak of the gaff needs to go higher and they will disappear.
Now, if the peak won't go higher its because its chockablock( is it?) or its because the single halyard( I'm thinking you have one gunter halyard rather than a seperate peak and throat halyard) is set up as far as it will go pulling in the luff component of the sail. If thats the case then perhaps the gaff halyard attachment point needs to go a couple or few inches higher on the gaff so that it pulls it in tighter to the mast( to get that peak angle correct)
It has to lift up first and pull in second. If the attachment is too low, it will pull up ok but can't fulfill that second part because it makes too acute an angle.
Another way to sort that out would be to let the boom go up a bit. set the sail with whatever controls your boom height loose and set the downhaul for luff tension last.that might allow you to get that gaff in tighter to the mast.

[Todd Bradshaw]

Usually, wrinkles from the clew which head upward to the mast on three-sided sails (which is essentially what you have here, even though it's a gunter) are "overbend wrinkles". The mast is bending too much to fit the luff of the sail. By the way, that's not a sliding gunter, it's just a gunter or more precisely a "folding gunter". A sliding gunter uses a plumb topmast section equipped with rings which allow it to slide straight up and down the mainmast. It does not hinge at the mast intersection as a gaff or folding gunter would and the topmast has zero rake.

You can start by applying enough outhaul tension to get the small wrinkles out along the boom. This will only move the aft end of the overbend wrinkle out to the clew corner, but it will put the strain where it belongs, on the reinforced clew area. Currently, it runs out to one of the aft boom lacing grommets, which isn't strong enough to take that kind of strain for long. The line of maximum strain on the sail is currently the overbend wrinkle. The rest of the luff, both above and below the wrinkle is fairly slack. To remedy this situation and get more even tension along the luff and across the body of the sail (and hopefully ditch the wrinkle in the process) you need to get the topmast more vertical (and/or maybe stiffer). It also looks like you could really use another few inches of topmast sticking up above the peak, as you seem about a quart low on luff tension along the topmast and don't seem to have much more spar to stretch the upper luff out along.

With a gunter, easing the halyard and allowing the topmast to have more rake is like bending the mast on a Marconi. It eats-up luff curve and flattens the sail. If you're trying to create draft, you want to straighten the mast and force the luff curve back into the body of the sail, where it forms draft.

As I've mentioned before, small boat gunters are often very difficult to design and build. You can only build the sail and it's luff curve to one shape with a limited amount of adjustability, but the spars are constantly flexing, bending and changing rake. A sail may set perfectly at ten knots and look absolutely awful at five knots or fifteen knots because the mast system is bending differently. There is no real fix for this situation other than inventing some sort of spars that don't bend. Sailshape is always going to be a compromise because of it, so the convenience of having your spars in shorter, stowable chunks often comes with a fairly hefty price.

Anyway, I'd certainly start by messing with outhaul tension and upper luff tension. Once the sail is smooth and clean-looking along those edges you can start playing with the mast/topmast junction and angle to see if you can get rid of the overbend. It also looks like you may eventually need to get the leech hollowed a little more on the middle two panels between the battens. Considering how flat the current distortion is making the leech area, there shouldn't be any curl or slack present along the leech. The photo seems to indicate that the leech is firmer 12" in than it is right at the edge. That's usually a pretty good formula for a flappy leech.

[rbgarr]

Yeah... what Todd said... I was just about to say all that (and in the exact same words!) but was having trouble tying my shoes :) :D ;)

[Joe ( Cold Spring on Hudson )]

Yeah... what Todd said... I was just about to say all that (and in the exact same words!) but was having trouble tying my shoes :) :D ;)

Spew :D :D :D

Yea yea me too :D

[WFK]

Thanks Todd for taking the time to spell that all out. I do find there is significant slack along the leech, especially when driving hard on the wind. It'll curl right at the end of the two lower batten pocket so of course I was wonder if longer battens would solve the issue.
A little longer topmast might be in the cards over the winter.

Bill

[Todd Bradshaw]

In order to prevent the leech folding over, battens need to be about three times as long as the amount of leech roach present in the area that they support. You can lay the sail out flat, run a string from the head end of the leech to the clew end and then measure how much roach extends past the string at each batten position. The mid and lower ones do look a little short. Probably not a problem when the sail is full of wind, but in light air it can be annoying as the whole thing wants to fold inward. If modified, they're going to be long enough (the top one already is) that it would be worth getting some tapered fiberglass battens with nice soft forward ends so that they don't make hard spots in the sail's shape. The top one should be a pretty soft batten (they're made in two or three grades of overall stiffness - either by varying core thickness or just by varying cross-section) and the other two can be medium stiffness.

[WFK]

Thanks again Todd, and I appreciate all the rest of the comments as well. It's been a great help.
I look forward to try and get her into shape on Saturday............

Bill

[WFK]

Wow Todd, what a difference! I took some time after work tonight and re-laced both the topmast as well the boom and that ugly crease is gone! It's truley a different boat going to wind! Thanks for the help.............
Bill