Building to optimise performance

Most of the old one designs have tolerences built into their rules which would normally be a set of dimensions plus or minus one inch I beleive. These were put in to enable the boats to be easier to home build but as you say they can be used to tweak performance. Theres no specific method of designing a fast boat though unfortunately. If anyone discovers one can you let me know asap as its gonna make the next few years at uni a damn sight easier....

Originally posted by foaminatthedeck Don't some of classes have a rule which states that if you build using the tolerances to opermise speed then the boat will not measure?

How can you define the difference between a boat built to optimise speed and a boat not built to the exact dimensions by builder error though? very tricky situation....

I'm totally sure how it applies, but with FRP moulded boats (i.e. pretty much everything these days!), the builder has to be approved as an authorised builder for the class. Part of this involves measuring the mould and a sample boat, and in some classes, if the mould is right on the limits, "authorised builder" status sometimes isn't forthcoming....

In theory, I think this has more to do with preventing boats that don't measure due to a very small manufacturing difference being sold, and the new owners then being told their shiny boat doesn't measure. My Fireball was right on the limit on the forward rocker station and a number of other measurements, but provided the builder can consistently build them to within a much smaller tolerance (I think they can manage down to about 1.5mm, but someone who actually builds boats might know better!) than allowed for in the rules there's nothing wrong with this.

Actually the Swift has rather close tolerances. I don't think a couple cm in rocker change would make a big enough difference. You would probably have to be a much better builder than average to gain much but then as with most things, a flat bottom might be faster off the wind but then you'll suffer a bit up wind unless you race in flat water. You might minimize the bow volume for windward performance but then you'll dive more off the wind.

I think the biggest gains are to be had in quality of the software on top of the water than any adjustments you can make under the water.

This will differ for boats that allow wide tolerances but some will not allow too much variance.

generally people try to minimse waterline beam and wetted surface. whilst keeping the lines nice and straight.

lots of compromises and things to weigh up. and you can never have the best hull for every condiotion