WOT Question

[stewtn]

I have a 22 FT pontoon with a 2015 Mercury 115 CT running a factory 15X17p black max prop. This engine is rated 5-6K RPM at WOT.
A couple of questions:

1. Currently running 85% wide open on the throttle I'm running at 4.9-5K RPMs and 22 MPH with a light load. Going WOT (the extra 15% on the throttle) has no effect on the RPMs or speed. I've checked the linkage and the throttle lever does move but no difference in engine speed, RPMs, or even engine sound. Is this normal?

2. I'm in the process of getting the toons cleaned for the season and I do know that getting them cleaned will improve my top speed. I bought a 15x15p extra cup black max prop and tested it out last weekend and saw almost no different in speed or RPMs. Since I haven't had a chance to test it out yet, will cleaning the toons also increase my WOT RPMs?

Thanks in advance for any advice.

 

[Chris1956]

Your prop likely has too much pitch. You probably want a prop or 12P or so, but try consulting a dealer or prop selector.

Unless the 'toons have some sort of rough coating like barnacles on them, I doubt speed with change much. 22MPH is pretty standard for 'toons.