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ISAF Sailing World Cup Melbourne
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Chris Williams: On Moth Culture And The New H-13
With around ten designs for the Moth class under his belt and years of competing in the class, Chris Williams tells us about the design cycle for the highly technical Moth sail, what makes a good sail good, and the best elements of sailing in the Moth class.
NN: Hi Chris, we know the new H-13 Moth sail is ready for the 2013 Worlds in Kaneohe Bay, HI this October. What makes the H-13 an improvement from your earlier generation sails?
CW: The boats have evolved, with most people upgrading to the Mach 2, and the sailors have gotten better - speeds have increased and, in the top half of the fleet, the sailors rarely touch the water except in tacks. This has changed the sail shapes to be much flatter and straight-backed. The boats are overpowered when on the foils, so the H-13 is designed with a lower center of effort by reducing the head width and adding roach to the sail. This is something I think will eventually filter down to yacht sails once the "style" of a very square mainsail is proven slower than a more traditionally roached mainsail. Another example is the TP-52 class mainsail which also has a smaller square head.
Mainsail photo of the H-13 Moth sail.
Before the switch to Mach 2s, Chris's North sail designs won five of the top ten places at the 2009 Worlds. The transition to the new boats was a period of trial and error, and eventual discovery. As Chris put it, "It became obvious that trying to sail a Bladerider vs. a Mach 2 was like showing up to the track with a VW vs. a Porsche. In the same respect, our sail designs needed an upgrade. After a few tries, we are confident that North will finally win a Worlds this year in Hawaii."
NN: Tell us about the design process for the Moth sail. What tools do you use? What are the competition using?
CW: Originally I used the whole North Design Suite: Spiral, Desman, Flow, MemBrain. This was helpful, especially for evaluating the mastbend and getting the luff curve close. I've probably built about ten different versions of the sails because the needs of the boats have changed as the class has evolved and we continue to learn more. My latest sail is a complete reset from my original sails and it took two tries to get it to where it is now. Having said that it is the most challenging class I have designed sails for. I use a lot of photos from practice to fine tune the sail and the tuning of the sail/rig.
The only other sailmaker in the Moth class is KA Sails. The owner and designer has been 2nd in the Moth Worlds quite a few times and is the designer of the Bladerider and the Mach 2. He uses a 2D design program he wrote for windsurfers.
NN: So its safe to say that you are one of two experts in designing Moth sails. In your opinion, what makes a good Moth sail good?
CW: Moth sails needs a good balance between enough power to get the boat foiling, and having the highest lift to drag ratio possible.
In addition, it has to be easy to rig and all six camber inducers need to function perfectly or it makes boat handling tricky.
Finally it needs to be easy to adjust on the water. A little change to the vang or downhaul can make a difference of 1-2 knots of upwind boatspeed (high mode for the Moth upwind is 14.5knts, low mode is 17knts). If the sail is too hard to get in the groove, you will not get the most out of the sail.
Andrew Lechte of North Sails in Japan has also created a sail design which has proven to be fast, especially in lighter conditions.
NN: There is a lot of interest in the Moth class, but much is left unsaid about what it takes to sail a Moth well. What are the parameters that determine how long it takes to be able to sail a Moth for fun, and then to get around a race course without being a liability?
CW: Fitness and sail handling are the most important. I like to think that if you can take a Laser out in 20 knots and feel comfortable sailing without flipping, you can handle a Moth no problem - with some time. If you cannot get a Laser around the course then you probably should steer clear of Moth sailing. Cat sailors and wind surfers seem able to jump into the class pretty quickly as well.
Moth sailors are very fun guys in general, so the social side of the regattas is always as much fun as the sailing. The class has done well with getting the right kind of sailors involved. We've also tried hard to avoid becoming an Olympic class, which many feel would ruin the class's culture. The top guys in the fleet are usually a little more organized than the new sailors and we spend a lot of time helping the new sailors out. We're all gearheads and there is quite a bit of tinkering on everyone's boats- but nothing is ever kept secret. Sharing is part of the culture in the Moth Class.
NN: Being an avid competitor yourself (and knowing that you work about 60 hours a week and have a growing family) how did you find the time to become competitive in the Moth?
CW: The truth is I can never find enough time to be at the top ten in the Worlds, but I still enjoy the challenge!
Check out footage of this year's
Moth Gorilla Camp
in Charleston, SC last month (video by Will Lyons).
Read more about the H-13 Mainsail on the
US Moth Blog
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