After having some alterations carried out on my Landy Main I asked Grant Piggott for his advice on batten tension. He reckoned you need just enough tension to make the battens pop from one side to the other. Thus not a lot of tension is required. However, I have now got into the habit of loosening the top three battens after every race and then re-adjust the tension prior to every race for the predicted conditions. Tight for light and loose for lots of wind. I can't say I really notice any difference but psychologically it feels much, much better so must be faster