I have a 14 foot flat bottom boat with a 433cc Yamaha mounted to it. I know the prop that is on there, not sure of size, is too small from the readings i have done. I have taken it on the water and it is slow. I know the boat will not act like a real air boat should due to the design of the hull, but i want more speed. Eventually, when i finish working on my Lake Buggy, i will have ideas to retrofit this motor into a wooden hull air boat made by me. Can anyone get me in the ball park with what size prop i need for a 433cc snowmobile motor that is mounted direct drive? I plan on using it in a 14ft alumacraft flat at this time. Thanks for any help you can give.