5.8 sail tuning

G'day I've tried all types of settings but I'm finding it hard to get my sail to stay full in the front 20% of the sail upwind. You can see in the photo's taken yesterday how its luffing, it does this with full rotation or only 45 degree rotation. The only way I've been able to fill it is by pulling on more downhaul that I want and depowering the boat. I was also supprised by the amount of twist, should I have had it on more? but that seems to choke the boat. Anybody know my error?
regards

Jeff,
. . . there are lots of variables. Pay attention to the jib, it is a large overlapping setup on the 5.8NA. Be careful to not oversheet the jib and pay attention to the jib block position, forward vs aft, inbound/out. It is easy to backwind the main on the NA.

Jeff,

It's difficult to tell from those photos but I can definitely see a really full deep shape at the bottom with the draft at or further back than 50% - it just looks like a sail with a bad cut/shape. The boomless sail is a difficult cut to get correct - is that a sail built by Nacra (E/P) or someone else? If you want to try and salvage the sail and get a little more out of it, you might want to try putting a boom on the rig so you can force the foot of the sail out further toward the rear of the boat.

Or just move your mainsheet forward on the foot creating more outhaul. It looks to have the track,but I can't tell for sure.If no track try the forward most grommet hole(if it's a class sail)Like Jake said ,the draft appears to be way aft.
Also looks like you need more downhaul,if you loose to much power ,try the other adjustments to get it back.

Thank's guys it's not a Nacra sail it was given to me it was fine but it may have stretched. This sail doesn't have the outhaul track on it so I'll try it in the next hole to pull the sail back, I was reluctant to do that as all my reading said to keep it in the middle hole but I can see from the photo's how full the sail is. The jib does a lot of drumming if its not pulled on really tight but when its pulled tight enough to stop the drumming you can feel it choke the boat, is the drumming a sign that the jib is too old? We had a pile of wind about 2 hours after that photo and I found it hard to point or have any speed up wind.

If the jib is "motoring" (flapping making the sound like a motor), the leech has probably stretched. You can probably tape in a couple of small battens (6" or so) horizontally on the leach at those areas and at least make the sail quiet. Sounds like it's time for some new sails though.

Thank's Jake I had the feeling that the jib was tired but really have never sailed anything with newish sails, so white with no holes looked good. I'm in the process of looking for a newer 5.8 anyway so I'll just have to find one with good sails.
regards Jeff

Jeff, does the cunningham on the nacra jib pull the sail up or down (attach to the head of tack)? If its up try a little more of this. The luff looks loose in the photo and lifting the jib even a little will allow you to tighten the leach without flattening the sail.

Thanks Scarecrow it does pull up, I've been running it looser lately so I'll try more pull on it
regards

you might also try a longer shackle at the bottom.

If you're downhauling and the wrinkles won't go away, I'd say the bolt rope has shrunk and needs to be "relaxed".

The rope inside the luff of the sail shrinks and can shrink A LOT, often a foot or more. You want to downhaul the sail material, not the rope. The rope just holds the sail in the track. The sail is only held to the rope with a few stitches top and bottom. Cut those bottom stitches and downhaul the sail and the rope will pull up into the sail quite a bit. Now the sail will slide down an extra foot, smoothing out the wrinkles and correcting its shape.

You'll have to feed a new bit of rope up into the pocket and stitch it in to keep the new piece from falling out. Alternatively, you can melt the new piece and fuze it to the butt end of the old before you cut those stitches. Then when you downhaul it will draw the new bit up into the sail.

Don't let anyone convince you that you pull on the rope. It does NOT need to be continuously strong top to bottom. It's only there to keep the sail in the track.

Look at your photo. You can see the wrinkles and yet your downhaul is tight. 15 minutes will fix it and add 10% to your upwind power.

Thank's David I should have said that photo was the worst I could find that actually showed the sail luffing. It was just after the start and a puff had just passed through that flattened a 5.7 and A just out of the photo before my wife pulled on much downhaul, it was one of those days where it goes from nothing to full on which was why she grabbed me going upwind. When she pulls the downhaul it sorts out the wrinkles no worries and sorts out most of the luffing so it doesn't show in a photo but it's still there. Chris I added a 6 inch lead to the bottom of my jib to fit in my downhaul arrangement, could the lifting of the jib create this problem?
regards

If your jig is 'luffing' when you sheet it fairly tight, move the jib block forward some, this pulls more tension vertically, and puts more tension on the leach, and will often stop the 'luffing', motoring, whatever you call it, it's slow.

And as has been said, it is easy to stall, or backwind the main with the HUGE jib of the Nacra NA's. If so, also move the jib block outward some. It hsould have the 4-way jib system on it, making it an easy thing to adjust.

Good luck, let us know.

BTW, from the looks of the one picture, move the mainsheet block clew forward a bunch, and then play with it to get things flowing right.

If you move the mainsheeting point foward on the sail, you may flatten the bottom but you will also induce hell of a lot more twist. the large amount of twist that you say you already have will be a good reason that the boat is not pointing [Pointing is down to jib and main leech control/tension]
It looks like you need to let the mast bend more to take some of the fullness out. i think that the 5.8s go with a 'soft' rig so you can loosen the diamond wires a bit. To stop this bend choking the slot, let some rotation off.
The trouble is, you may end up with a totally gutless boat with no power on this set-up!

New sails time maybe

I just got rid of my old dacron on my N5.7, an went to a mylar. I had the same problem with the sails chocking in the heavies. With the main bellying out so far, it chocked off the slot. I couldent point at all. on a reach, in even moderate wind i would be over powered. It was like riding a bronco. New Mylar squaretop = new boat. The sail can be shaped any way you want it. I tightened up the diamonds, added rotation, no more chocked off slot. tons of useable and controllable power.
I think your sails are tired. Look around in the winter, there are some great deals out there.

Thank's guys I'm going to have a play with settings this weekend. The main sail was holding a good shape until I started playing with the jib or I may have stretched it. I have the loose diamond wire setup where you can just make the wires touch 18 inches up from the bottom. I'll see what I can do with various settings before the race on Saturday.
regards