Mainsail attitude or altitude?

[slowpoke]

Hi folks, I know we talked about it on the old site a little, but frankly I can't remember what the outcome was. The question is, during the last epoxy cup, which type of main seemed to work best in the light air you raced in? For the guys with the mains with a more traditional shape, if you had the money, would you buy a new "barn door" main? And what happens when the barn door gets out there in 15-25kts? Do you have reef points?

Here on the west coast we tend to have 5-15kt winds during the day, sometimes a little more. The question for me is will I be overpowered with a barn door? What does everyone think?

[Ron Bowman]

No reef points on our barn door sail. It's possible to reduce power without reefing. Flatten the main, drop the traveler, put a bubble in the luff and only power up the back side (leech side ) of the sail. We've sailed on some windy days and never felt that reefing would have been necessary. One thing the large head mains do is twist off at the top. Kind of an auto depowering system when sailing upwind. In a gust, the top catches air, the mast bends so as to flatten and depower the main and then the top twists off to release air.

As far as comparing performance during the epoxy cup, it's tough to draw conclusions from those four light air races. Upwind performance was fairly close and sail area was similar among the three boats – just a different shape. I had some prebend/trim issues that I couldn't sort out that hindered our mainsail trim. Hitting the shifts made a big difference in those conditions. Downwind performance was much different among the three boats but I did not believe that was because of differences in mainsail shapes.

All in all, mainsail shape differences didn't have a lot to do with the results at the epoxy cup, in my opinion. But in heavy air, a square or large head main will depower itself in gusts. 15 knots of breeze is manageable with either a square head or more traditionally shaped main. Above that, a square head sail will depower itself and can be easier to sail than a traditional main. You need a flexible rig to depower like that, though.

Ron

[Tim Ford]

I'm going with what's basically Ron's main, same company, same designer (I think) or maybe not...can't remember if you used MAD sails, Ron. But along those lines, please refresh my notoriously bad memory: did you add the second set of spreaders due to the flat head? Or was that a kite-related decision? (trying to save myself having to build a set of spreaders as slick as Ron's, which would basically be impossible as his are awesome)

[Kevin]

The difference between Ron's main and mine is the leech shape. Basic sail area are about the same (mine is 160sqft). He has more head width and a hollow leech, I have more girth in the middle and a positive leech. The theory behind Ron's main is that the hollow leech will allow the head to fall off more easily when you need it to because the leech isn't a continuous curve. I believe that this beta came from Laurie (who is F15 and a sail maker, co-owner of shazza).

Pre-bend and rake also greatly impact performance of the main. The sail has to match what you can create with the spar. For instance, I was running more pre-bend then both Jeff and Ron (and more than the sail was designed for). Shazza has something like 8" of pre-bend which is a ton. Vipers have balanced out at around 6" of luff curve I think, a few rigs were lost when a low amount of pre-bend and heavy conditions resulted in some inversion. Pre-bend helps support the tip and keep the mast in column with the single spreader c-tech rig.

Kevin.

p.s. This is the complicated stuff that makes sailing such a challenge.

[Ron Bowman]

My main was built by MAD sails too. Ryan Malmgren is the sailmaker.

As far as the second set of spreaders... I added those because I was a little bit concerned about the masthead kite and an unsupported top on the rig. We first sailed Lunatic Fringe late in the season in 2009. We were knocked down a few times with the kite up and I didn't like how the tip of the mast was flexing forward. I added the upper spreaders that winter after putting the boat away. We might not have needed the uppers but I went ahead and put them on during that off season. Gives me peace of mind but also encouraged me to fly too much sail one day and we blew up the compression post and tore the cabin top to shreds. The mast was fine. Kinda exposed the next most vulnerable spot in the column - in my case an under-built compression post.

Ron