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Strange noise at high rpm

My guess is that it does it mostly in the turns.

The motor sounds like it is cavitating or trimmed too high.

Basically, the prop is running out of water to dig into. It does not sound like anything is wrong with the motor.

This happens a lot if the motor is mounted too high.

If this boat runs good at other times, I would try trimming down a little when going into turns while pulling the inflatable and it may go away. I would not change motor height just for this periodic occurance.

One other thing you could do is, take your prop to a good prop shop and have them put some cup in your propeller blades. That will help them dig in the condition that you videoed.

I am sure others will jump in with some of their first hand experiences and solutions.

Mike
 
Yes sound seems like cavitation, engine mounting height, engine trim angle, while you pulling inflatable and turning extra load and prop not get sufficient water from down of the hull.

mike-. Is That Hydro Stabilizer which is fix on the cavitation plate,would help for him ? i have seen some boats with single engines they fixed that plates.


wajira
 
I have found that hydrofoils help getting a boat up on plane....I can not say if it would help with the cavitation. I try not to use them unless all else was tried.

Mike
 
Thank's for your replies. I will try to adjust the trim better and see if that was the problem
The motor seems to be a little too high, but except turnings it runs great.
 
The motor may be set high so that the boat gets up on plane easily. The lower the motor is set, the harder it is to plane. Steering can start getting weird also if motor is set too low.

Mike
 
Initially, the anti-cavitation plate should be set to be dead level with the lowest point on the transom. I suspect your engine is set too high.
 
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