Most of this thread has been about individuals arguing engineering theories applied to boat design. They are called theories for a good reason. In reality there is very little engineering fact when it is applied to the real world. Things are far too complex. Engineers use the theory to guide them toward a design. Bill Roberts designs good cats, it doesn’t matter if you don’t believe in the theories he has used to reach that design. The proof is in the pudding.

A good example of this is Mary’s proposed sliding mast design, in reality it will not give a larger righting moment see http://www.wingo.com/proa/rig_placement.html ( I think that is what she was getting at, forgive me if I am wrong). But if she went and built it she would probably find it does give more power for a number of other reasons, so building something based on the wrong theory is not necessarily a bad thing. The important thing is to try things out.

Mary, if you or any other non engineers want to understand engineering better I would recommend the book “Structures or why things don’t fall down” by J.E. Gordon its available in paperback about $12 on amazon.

In boat design, because conditions change every time you sail, then its nigh on impossible to say you have a better boat than the next man. Using a system of rules narrows the field down and allows a little more comparison, which appeals to many people (not me). I believe the ultimate measure of a boats performance is the size of your smile. If you hadn’t guessed I am a design engineer (engines) and amateur boat designer/builder and my interpretation of the theories are very strange indeed.

Gareth Roberts (no relation to Bill or Carl)