Air vent for props????

[coldwater]

1234

[Pismo]

You really only need those on boats that wont plane off without them.

[Pismo]

They dont do anything at high speed because they are high and dry. Only to get air into prop to plane, get the revs up.

[gpapich]

If you are running your drive high enough to be considered surface piercing when planing, you might want to consider venting your prop, especially if you are running a surfacing prop (cleaver, etc.).

This typically applies to the guys running big props with monster pitch and having trouble coming on plane. As one of the other guys said, you need to get air to these big props otherwise it'll bog the engines until you're up (if you ever get up.) Again, surface piercing designs only (ventilated, not cavitating).

[gcarter]

Actually Sonny Renato Levy ran into a similar problem in Italy in the late '60's. He built a largish twin turbo diesel powered race boat w/ a Vee drive and couldn't get the engine revs up to get boost w/the turbos to get on plane. Remember there were no HD outdrives in the '60's so Vee drives were the only alternative. His solution was to install a air pressure tank on board w/ an outlet just in front of the prop at the strut. He'd turn on the air to get on plane.
But he had to have gotten the idea from somewhere else.....
Maybe the idea has been around longer than we think.