Still trying to make up my mind on a new flat bottom boat for this year. Here is some info on tunnels a guide on the MN river directed me to. Thought it was interisting.
http://www.snyderboats.com/seven_steps.html
Thought this was very good info for anyone considering a tunnel hull. The person I got this info from sounded like he may of had to learn about the cavitation problems of a true flat bottom boat the hard way.