I have spent the last 3 weeks helping my 10 y.o. daughter and her
classmates design and build 3 solar boats. It was a kids project so I
didn't design them, but did tell them what makes boats fast: long
skinny hulls with just enough buoyancy to float, just enough RM not
to capsize and as light as possible.

They designed and built a short, stubby trimaran; a big hulled, max
width and length cat and a wide, flat bottom mono. The cat and tri
had enormous freeboard. They competed against 25 mostly 11 and 12
year olds from other schools and the cat won overall, by mms from the
mono, with the tri knocked out of it's heat a small distance behind
the mono. The mono set the fastest time for the day. Very
satisfying from a teaching/mentoring point of view, but didn't do much
for my design credibility!

rob