On another thread there is talk of how a sail's luff may not be right for the mast.

I am interested in what to look for, what to measure, what to keep in mind when i am at Robbie's or some one else's yard/sail sale.

I recently shredded one of my used Tornado sails (808) that seemed (to me at least) to be perfect. I have another T sail that handles heavy air well. but is no where near as sensitive/responsive as the 808 sail,

I couldn't tell you how well its luff cut, fits my mast shape.

I may try to repair the old sail, but really need to look for a replacement for the light wind of the summer

Thanks,

First off, I am not a fast racer, but love boats, so here is my two cents on this topic. Overused sails are usually powerful. As the chord is blown deep and the sailcloth stretches out, the lift generated by the sail is substantial. These sails are fast on a reach, but are generally non-tunable in heavy air (don't depower in response to downhaul/cunningham), and don't point so great.

Start with your tuning guide to get your mast pre-bend close to where it should be for your weight. Then hoist the main with the boat fully rigged, and loaded, including main sheet blocks, with the sail on the mast head hook, and cunningham attached, but **WITH THE LUFF OUT OF THE TRACK**.

Compare your mast bend to the mainsail luff curve, when the down haul is near full on, and mainsheet blocks relatively tight. The curves in both the main and the mast should more or less match up, and your sail should flatten. If they match, and the sail flattens, it indicates that the combination of mast and sail has a broad range of tuning with the cunningham and blocks. If the sail has a big curve on the luff, looks baggy, either the mast requires more tuning to compensate, or the luff of the sail may require recutting.

While it is up this way, you may want to take a close look at what changing the mainsheet tension and cunningham do to interact with each other to create and decrease chord depth of the sail, and induce mast bend. It's kind of interesting.

Ther eis some valuable information here, as it applies to the A-Cats
http://www.usaca.info/index.php?option=com_content&view=article&id=229:landenberger-tuning-tips-mast-setup&catid=13:technical&Itemid=31

good info, thanks.

I dont really know of any tuning guides for my cat (mystere). If there were any, they would probably be in French... but worth looking for

i think i would have to do this with my current sails.. and really get a good picture of what is working and not... and then when i look to purchase new sails (used) bring mine with me to compare.

Who suggested doing this, I assume you picked this up from someone else?

I read it somewhere, I think it was a Landy suggestion. It really makes sense. Try it!