The first question is "what type of boards are they racing?"
This is pretty important. Assuming that they plan on course racing (as opposed to say, slalom) there are two main types of boards that are raced today- longboards and formula boards.

Longboards are about 12ft long, narrow, and have a centerboard. They are generally slow (in my experience) and will most definately require that you set a shorter course. Depending on the skill of the people racing, their ideal conditions will be anything up to about 20kts. The cats will probably beat them in every condition.

Formula boards are less than 9ft long and very wide. Their intention is to plane around the entire course (upwind and downwind). They require a minimum amount of wind to race (much less than 10kts and they will not be able to plane consistantly- which means they shouldn't be racing). If they have enough wind, they will be about as fast or faster than the cats (depending on sailor skill). The same courses could be used.

If both longboards and formula boards are going to race, it would probably require separate starts (and possibly courses) as they really don't work well on the same start line.

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