rig tuning

From our fairly recent experience of the same thing, I would say that the banana shape of the mast is correct. It looks extreme but we set the boat up with a forestay length of 9.932m as recommended in this forum with 32 caps and 28 lowers Loos gauge. The bend is radical but no more so than an X99. All I can say is that Farr Out goes like a train upwind now - downwind the forestay is very very slack but that doesn't worry me. This summer we mistakenly left the old ragged dyneema core backstay on whilst doing 9 knots under kite - the backstay blew to pieces but the rig stayed up...

I appreciate the input. Simone, at 32 the pre-bend is significant and the lowers could only reduce that if screwed down very tight which would then limit the side bend and cause the top to fall off disproportionately to the bottom and mid-section. If I have it right, the 32 is about right to get the required fore stay tension, and the "banana" is a result of that. Hence the main needs to be cut to suit the curve of the mast since curve can't be reduced without either reducing the tension in the uppers, losing fore stay tension, or modifying the mast butt-end cut (heaven forbid). Am I understanding this correctly?

Much thanks to all so far.

This is one of my favorite topics. I've had my boat 3 years now and of course, I'm always trying to get more out of her.
I have a North kevlar main that came w/ the boat and I don't know what kind of curve it was cut for. There is a good thread in "what the winners use". At 32/28, my main hangs with a big wrinkle/sag down the middle. At 32/30, it looks better but not perfect. In the Spring, maybe I'll take a shot at 30/30.
I'm wondering if I should replace the main and if so, with what. I remember a post recommending a Laser28 sail-maker in Canada, but I can't find the post... can someone remind me?

I'd be interested in trying out a used mylar main that Denise has cut but I'm assuming that everything is being cut from Dacron for the one design. fj

Hi Denise,
Your correction is accurate, when I said "mylar", I meant an aramid laminate type sail. And I was thinking laminate because I didn't think there would be a used dacron main available that was still crisp. Your offer sounds like a great idea, thank you, john

Hi Billman,

You should read this topic http://www.laser28.org/forum/forum_posts.asp?TID=282

I suggest you measure your fore stay pin-to-pin while it is up. We use a mast tower to do this, but using a chair to get to the top of the fore stay is not a big deal. While set up to do this measure, also measure from the center of the top pin to the top of the swage at the bottom of the stay and mark that distance. Then you will always be able to relate that to adjustments you may make from time to time in the total length. Don't forget to write that number down in a safe place. In fact, put it in three places so that it doesn't get lost.

There is much written on the tuning of these boats. Most comes from owners/sailors active in the one-design racing, and largely these people have the most experience with the boat. However, most are using sails that come from the same loft. No doubt that loft has more experience than any other working with the Laser and using their sails and tuning information is the quickest way to get maximum drive from a set of sails and rig. However, if you own a set of sails made by another loft, then some of that tuning information becomes less applicable, except for fore stay length. My own boat has sails from another loft and I suspect my main is cut flatter and won't set well using a typical 32 loos on the uppers and 28 on the lowers (a common average among the OD fleet). Such a set-up provides very substantial pre-bend and if your sail is not cut to that then the sail will become far too flat. When you slacken the uppers to fit the flatter main, you will then sacrifice fore stay tension requiring fuller cut head sails.........etc, etc, etc.

In summary, set the fore stay length starting at the 32'-6 3/4", and then set the shrouds to a tension that fits your main sail. Experiment with fore stay lengths within +-3/8", but I doubt you will like anything shorter than 6 3/4" because the helm will have no feel. Have fun!

Usually the reason for the bananna rig is to get more of the leech of the main at a 90 deg angle to the airflow over the sail. This simply makes more use of the sail area that you have, and it also can change the neutral rudder angle as well. I just had a really flat main made, but I still prefer less prebend so I can get more adjustment out of the backstay. I also like to keep my uppers and lowers loose, so I can get the number 1 sheeting angle a bit tighter, and for me a little power loss is ok because I race single handed.... well, I didn't get to race the laser at all this year... darn job...