prop slip

[ril0]

have fitted merc 150hp seems like prop is slipping but have tried three different props with same result .When revs get to 1500rpm prop seems to loose grip and revs rise with no increase in speed . Engine install is correct and dont think can be cavitation as revs not high enough .Is there a clutch or anything in gear box that could slip reverse is fine and there dosnt seem to be any grateing or grinding noises .Also drive feels smooth with no jumping or clunking when selecting gears .

 

[AMD Rules]

Re: prop slip

The drive system is direct, without a clutch. What you describe is indicative of a loose prop hub, but since you have tried three different props it would seem that must not be the case.

It must be a ventilation problem. Is your motor trimmed all the way down? Where is the antiventialtion plate in relation to the water surface when you reach that rpm? Have an assistant look at the position while underway. Do you have any obstructions mounted near the motor on the transom, that may be interfering with the clean flow of water to the prop? Weight distribution of the boat...nose heavy?

This is another topic that is better suited for the prop forum, located here:

Prop Questions and Topics

 

[JB]

Re: prop slip

Repost in the Prop Forum.