THRUST FAN

[redsled]

anybody try big air boat fans out. waterwalker maximus or whirlwind whisper tip. only need big hp to turn fast?

[bphillip2]

We use the 84" Ivo Paddle prop on some of the Explorer models. It has a 5.5 inch wide blade requiring a larger reduction ratio. The common airboat props have very little application for our designs.

[redsled]

Turn it slow with big blades to get tip speed down ?

[bphillip2]

Yes, we do that. Tip speeds are below 450fps, often under 350.

[jchovernut]

Big airboat props cost bit $$, too!! Remember, they're pushing several hundred HP through those things and some models are pushing the tips supersonic at high power settings. I live in Central Florida and am around airboats a lot. When they put the power on, you literally 'feel' it!

I'm considering experimenting with the KOOLProp when I eventually get to finishing up my 18' Prospector. On one of my next trips to Montreal, I'm going to visit the North American importer over at AirTrikes. The props are made in the Ukraine. They have models designed with airboats and hovercraft in mind. Some models have little winglets on the tips for supposedly quieter operation. I'm going to see if I can hear one run either up at AirTrikes, or at this Spring's Sun-'n-Fun EAA Fly-In over in Lakeland, FL.

Like Bryan said, he uses the Ivo 84" paddle blade prop for the Explorer-22TDI; it's a really nice prop! Also, he's using the PowerFin at its full diameter on the new Carbon-90 drive powered Surveyors & Vanguards. I believe that's 75" or so. It's amazingly quiet with the 40HP Kohler engine setup. The nice thing about the Ivo 84' and the PowerFIn is that at their diameters, they can be run slow enough to keep the tip speeds quite low resulting in a very quiet manner.

John Carter