short shaft ventilating in turns

[whywhyzed]

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[steelespike]

Re: short shaft ventilating in turns

Your height is about right.a long shaft will just cause problems. You could see if a prop shop can add some cup to the prop.Or you could buy or make a wedge to go between the mounting bracket and the transom so you can adj 1/2 a notch.A little more diameter
on the prop could help also and in the extreme 4 blades.I would try the trim and prop cup first.

 

[MikDee]

Re: short shaft ventilating in turns

IMO your motor is too low! The cavitation plate, (the plate just above the water inlet holes) should be flush with the bottom of the boat! If it's a short shaft motor it should only be 15" long, not 20".

 

[Snowdrggn]

Re: short shaft ventilating in turns

When I first put the inflatable I have now in the water, I had a really bad ventilation issue. Make sure the pieces that hold your floor boards down at the transom are as low as possible so there is no "hook" at the bottom of the transom on the bottom. I also went to a Piranha prop which made a big difference. Inflatables are notorious for not having the floors sit flush with the bottom of the transom.

Cheers,
Snow.

 

[MikDee]

Re: short shaft ventilating in turns

Go figure, when you trim (angle) your motor up, it being that low, water is hitting the top of your cavitation plate, and being thrown back at your transom.

 

[whywhyzed]

Re: short shaft ventilating in turns

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[Laddies]

Re: short shaft ventilating in turns

If you can't adjust it out by moving the engine, take the prop to a prop shop and have them double cup it. We use to have problems with a house boat and thats what fixed it.

 

[Franky219]

Re: short shaft ventilating in turns

I had the same problem with my 12 ft Zodiac. I put a hydrafoil on it and the problem went away. I know alot of people say their worthless but it totally fixed my problem.

 

[Franky219]

Re: short shaft ventilating in turns

Just thought of something else! Go to allinflatables.com They have planing trim tabs. A buddy of mine put them on his inflatable and says they work great.

 

[MikDee]

Re: short shaft ventilating in turns

I still say your cavitation plate is below the transom quite a bit, you need to move it up to slightly above the transom. (out of the way of water flow). Aside from this, (in the pics) it looks like the rear bottom of your hull is angled up towards the transom, and extra water flow is being directed up to the top of the cavitation plate, when tilting the motor up, it stands to reason water is shooting back at you, and taken away from the prop, compounding this problem!. No wonder you have cavitation problems at times, and in turns. A hydrofoil would probably help all around, BUT, it mounts on the cavitation plate, and also needs to be slightly above the transom, to sit on top of the water when planing, (not dig in!)

P.S. I think your motor needs to go up at least 3" guessing from the pics.