Cavitation Problems

[cpenrose]

I have a 12' saturn inflatable with a 2004 johnson 8 hp. I got the motor today and every time I went to get on plane and the stern started rising, the engine would lose , I don't know what it's called for boats, but traction. It would just rev real loud, and would slow down. I couldn't really get on plane all day. Do I have to cut my transom down?

 

[Another retired guy]

Re: Cavitation Problems

With the motor lowered, the anti cavitation plate should be level with the bottom of the boat. If it's more than 1/2" higher, then the motor is too high.

Another possibility is the prop - it may not be correct size/pitch for use on an inflatable.

 

[cpenrose]

Re: Cavitation Problems

It's pretty hard to keep it at a certain depth. With someone on the bow it could easily raise the motor 2 inches, so I don't know when I should look to see how deep it is. Say it is too high, should I cut the transom down? And is there a way to find what type of prop I need?

 

[Texasmark]

Re: Cavitation Problems

Before you do anything keep "bumping" your question to the top till a person on here answers you who is familiar with inflatable problems. You are after ventilation, not cavitation. Ventilation is sucking surface air into the prop slip stream reducing the water volume and thus the thrust. Cavitation is air bubbles associated with disturbances around the prop blade tips. The plate is an antiventilation plate.

Seems inflatables are different critters and require special attention.

Mark

 

[chriscraft254]

Re: Cavitation Problems

Might have a spun prop as well, but I doubt it on a 8hp motor.

 

[cpenrose]

Re: Cavitation Problems

Ventilation sounds much better. Didn't know how air being sucked down made cavities...