I have a 15.5 ft Avon inflatable with a 40 HP outboard. It is cramped with 4 divers with 2 tanks each but workable. I have had 4 divers and a pilot but we only had 1 tank each on that trip. Normally we dive 2 people at a time while the other 2 gear up which makes things easier. The large tubes on the Avon make it very stable.