The role of the battens

I understand the function and the basic knowledge of what the battens are for, but just don't have a good understanding of batten tension and what conditions are best for what. I'm assuming light air more tension to get more sail shape, and flatten out (less tension) the sail in higher winds. . . ? ? but not even sure it's that simple. Also because my 18 is new to me, the previous owner seemed to thin out the first 2-3 feet of the battens to make them more flexible. This is more on the bottom 1/3 of the sail then not so much on the rest. Good, bad? ? ?

I did a search on battens, but didn't get much info. Am I over thinking things. Is this something I just get a feel for in the conditions I sail in. Thanks.

I've found that batten tension plays a pretty minor role in sail shape. The batten curve and the sail cut are much more significant. We tension our battens the same for all conditions. Just tight enough so there aren't any wrinkles along the batten pocket. Overtensioning the battens can make the sail not want to "pop" when you change tacks.

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I only have two years of hobie experience so I cannot comment on the effectiveness yet of the battens. I have been windsurfing for 30 years and I can tell you the battens make a huge difference in sail performance especially in the light and moderate winds. A few of the things they do are;

Leech stability
Draft stability
Minor sail shape

Here is a good article describing the batten's purpose:
http://www.sailmaker.com/articles/fullbatt.htm

Generally though the sail maker determines the shape of the sail, but with thinner battens for the first 2-3 feet of batten will allow the draft of the sail will stay closer to the mast vs. moving back in the sail. Also, tighter battens will slighly force the main sail to bow, which increases the draft of the sial and this will benefit light to moderate wind sail performance. I say slight because this is more dictated by sail make not batten forcing.....

Hope this helps. I know other have way more experience with Hobie sails and they should weigh in with their extensive experience.