[LifeIsGood]

Guess that is what led me to believe I had used the wrong terminology. I have not run full throttle trimmed down. Original post:
WOT trimmed up would get me to 5k RPMs. Running with 19 [correction - 21] pitch prop. Had it out this weekend and noticed I was hitting 5k RPMs at only 3/4 throttle trimmed all the way down.

[Andy b]

Originally Posted by blockp

I wouldn't think small burrs on the blades would have that much effect... unless you buried it hard and took some cupping out of blades or something like that.?

you'd be surprised how much Cavitation a rough leading edge can cause!

Cavitation occurs when pressure on the water across the blade’s surface is reduced to the point of becoming water vapour, forming bubbles.
If these bubbles burst, they can cause a cavitation burn which can deteriorate the propeller’s surface and cause negative performance issues.
As this condition can cause an increase in engine rpm, it’s often confused with ventilation.

[LifeIsGood]

Thanks Andy b,
I have experienced cavitation in the past but typically on a sharp turn. I do not believe that is what I am experiencing now though.

I do appreciate the response.

LifeIsGood

[mikeyt]

Originally Posted by LifeIsGood

Thanks Andy b,
I have experienced cavitation in the past but typically on a sharp turn. I do not believe that is what I am experiencing now though.

I do appreciate the response.

LifeIsGood

Sharp turns dont cause 'cavitation' but you can experience 'ventilation' during sharp turns.... as Andy noted, they are easily confused.

[Andy b]

Originally Posted by LifeIsGood

Thanks Andy b,
I have experienced cavitation in the past but typically on a sharp turn. I do not believe that is what I am experiencing now though.

I do appreciate the response.

LifeIsGood

Ventilation is when air is drawn in around the propeller blades.
Normally, this causes a gain in rpm, but a loss of speed, since the propeller blades are not biting clean water.
This most commonly occurs during hard cornering or in certain water conditions, such as following seas.

[Andy b]

If you look here you will see how the water vapour is formed on the blades edge.