Inflatable catamaran 9.9hp case file

I would like to find the most efficient prop in terms of offering the least amount of prop slip. I am interested in attaining the fastest cruising speed available if I don't already have it.

Current prop is Yamaha aluminum 9.25 x 9 pitch 3 blade

2008 Yamaha 9.9hp short shaft 2 stroke 2.08 gear ratio (I completed initial break-in 1 month ago) 4500-5500 rpm

2009 Aquamax 9.5' inflatable catamaran

Boat weights 100lbs + 3 gal fuel + 81lb outboard + 2 people together weighing 230 lbs (100f+130m)

WOT 5400 16mph

note: with just me in it 18mph sans the 100lb female
note: borrowed a Yam 9.25x12 3 blade AL WOT 3800 15mph

I want to try both the Turning Point Rascal AL 9x9 and their 9x10 3 blade

Plenty of other possibilities are available as well from SS, going up to 4 Blades, composites, as well as Yamaha's "Duel Thrust" plastic and aluminum options that I vaguely understand modulate the exhaust venting for less initial slip designed for bigboats/ sailboats.

Thank you just trying to learn something

Re: Inflatable catamaran 9.9hp case file

On a good day on a light reasonably fast boat your 9,9 should approach about 21
mph. Unfortunately while your inflatable is light it isn't particularly fast.The hull shape doesn't really get up on the water very well.The hull type doesn't make much of a foot print for getting up on the water.It probably flexes both from wave action,motor stress and weight placement. If you don't have any ventilation(cavitation) problems you might be able to raise the motor.On a regular hull if you can't see the anti vent plate (just above the prop) at speed you should raise the motor. Motor trim is also important. You might gain a mph but I really think your pretty close for the hull design.Its possible a tiller extension so you can sit forward more, perhaps both sitting on the middle seat.Be sure it is infalted to maximum pressure.