propulsion
best of luck with the project, you are going into unchartered water here! Fireboat has a brushless single screw in his, its quick, but is the 3 foot model, and HS93 has twin outrunners in his small Fireboat, its very fast, but dont know how you will get on with the bigger 4 foot model. The problem is expense I think. You will need the 2 motors, 2 esc's, two lots of packs, if you go to all the bother of the motors and esc's there is no point spoiling things with a poor battery supply.
If you wait a week or two, HS93 and I are almost finished sorting a brushless setup on my 4 foot Huntsman 28, so the size and weight will be very similar. We did many months research, but there isnt much info to go on as most Brushless set ups are with the lightweight and smaller Fast electric race guys who have very different boats to us.
With the 3 foot Fireboat hulls, they become very unstable being narrow, it will be very interesting to see the 4 foot going brushless as it shouild handle far better.
Keep us posted with your progress,