Cavitation plate above keel (pic) will this work?

[gwoloshyn]

I've recently built a Glen-L boat and installed my short shaft motor. Right now, my cavitation plate is about 1.5" above the bottom of the boat, how much will this affect my performance on plane? Also, I'm concerned with water pickup. I know it's ideal to have the plate in a straight line with the keel of the boat, but this would require me cutting down my transom (maybe a winter project if I can run it like this now). Thanks

 

[H20Rat]

Re: Cavitation plate above keel (pic) will this work?

(ventilation plate, not cavitation, huge difference... there, got that out of the way!)

How big of an engine is that? It looks like its a fairly decent size. The reason I'm asking is that the smaller/slower a boat is, the higher you can get away with running the engine in relation to the bottom of the boat. At 15 mph, the surface of the water is going to be substantially higher on the motor than it will be at 50 mph.

All that said, gut feeling tells me that motor is too high. You will have to run it for test no matter what, but I expect the prop is probably going to ventilate, especially on turns.

 

[Philster]

Re: Cavitation plate above keel (pic) will this work?

Bottom is flat? Heck, being 1.5" above the bottom is fine or low.

Being even with the bottom is called for on most any v-bottom boat. The flatter the hull/stern, the higher up she goes.


Edit: water pickup. The water will come up from the stern/bottom and push up against the AV plate. Really, 1.5" above the bottom is nothing at all. It's quite right actually.

If you took the pic right, with the motor trimmed vertical and not trimmed out, the AV plate would be measure even less distance from the bottom so... really, no worries.

 

[gwoloshyn]

Re: Cavitation plate above keel (pic) will this work?

Thanks for the info. The engine is a 30hp on an 11 ft Glen-L TNT. I'm about to go test this later this evening, how does the motors trim position look for starting? Should I make any adjustments?

 

[NSBCraig]

Re: Cavitation plate above keel (pic) will this work?

Oh I wanna play with that!

 

[MWG2600]

Re: Cavitation plate above keel (pic) will this work?

Go test it, get a water psi gauge if you are worried. Looks like a lot of fun, I bet it works good!

 

[jestor68]

Re: Cavitation plate above keel (pic) will this work?

I agree that you are likely to experience some ventilation with the anti-cavitation plate that high above the bottom. :facepalm:

 

[BonairII]

Re: Cavitation plate above keel (pic) will this work?

Hopefully your motor has a telltale. If so, if the pee stream lessens or stops altogether at WOT....then the motor is too high(and not getting enough water)

 

[catfishcarl99]

Re: Cavitation plate above keel (pic) will this work?

Thanks for the info. The engine is a 30hp on an 11 ft Glen-L TNT. I'm about to go test this later this evening, how does the motors trim position look for starting? Should I make any adjustments?

View attachment 155414

that looks scary.

 

[jestor68]

Re: Cavitation plate above keel (pic) will this work?

Start with it all the down(in) and adjust from there. That little boat will be very prone to porpoising. I doubt it will tolerate much trim.