WOT Slower than lower RPM...

[SeaBreeze]

First time I have had the oppourtunity to travel a distance at WOT but found my best speed was at 6000 RPM vice 6300. It has a stock Merc prop.

[jrolin1]

It should not be that way unless your hub is slipping. I could understand it if it is not much faster at wot, but not slower.

[Bamaman]

I take it the GPS is running in KPH instead of MPH with 90 hp.

[Bryden24shp]

I bet the prop is cavitating a little bit at WOT. Did you try to bring the trim down a little to get it to bite at all?

[SeaBreeze]

I bet the prop is cavitating a little bit at WOT. Did you try to bring the trim down a little to get it to bite at all?

It could be cavitating a little, I was seeing about 29mph at 6300 rpm, I trimmed up and down but just lost speed both directions so that was as fast as I could get it at WOT. As I slowed down the rpm a little it picked up .2-.3 mph.

And, no I do not have my GPS set on KPH. I am in the ballpark of what the dealer said I would get with underskin and lifting strakes (their version of perfomance package).

[Bryden24shp]

When you are running WOT, have someone steer for you and run back and see how far the prop is in the water. Look at the cavitaion plate on the L/U and see if it is running out of the water. With the new prop I just ran, the cav plate was about 3" out and I could hear the props ears slapping the water. If you are little too far out, it will ventilate.

[Tlowry]

I take it the GPS is running in KPH instead of MPH with 90 hp.

I think 29.2 is believable.


Sounds like it's starting to suck air at the higher RPM to me too.