I've got Bethwaites and a lot of other books but understanding and using the theory is my problem. Last Saturday we raced in light puffy wind on a big lake and got hammered. At tea the RO said always head starboard tack as you round the bottom mark. We did that on the Sunday in plenty of wind and 2ft chop and got 50m on the boat on the other tack. How does that work? I cant understand the theory as to my mind I was travelling the same distance.