is this correct

[djohnalyn]

increase pitch = decreases rpm's / increases mph/ decreases wholeshot?

decrease pitch = increases rpm's / increases wholeshot / decreases mph?

I have a 17' bayliner capri w/85hp force turning 4900 rpm @ wot. (operating range is 4500 - 5500) I DONT KNOW MY MPH

boat weight is appropriate, the boat planes quickly (5-6 seconds), the engine is at the correct height, motor seems to run well. However, I want the engine to reach its peak of 5500rpm.

I currently have a 13 1/4 X 15 michigan allum prop on it...

any thoughts or suggestions

 

[Texasmark]

Re: is this correct

Not necessarily so. In theory yes, but in practice other things move on you and modify your anticipated results. BTDT and I am not the expert.

For me, changing types of props had an impact, as did hull drag.

Different prop types give you different performance......so you have to keep it apples and apples...same mfgr., same prop type.

By getting better performance out of the hull with more pitch (in my case) the boat drag was reduced (less boat in the water) so I got both increased rpm and increased mph......on one particular setup which is the only one I am using for reference in answering your question.

Hole shot can be modified (improved) by adding "ports" to the prop to let it ventilate on the shot. Has no affect on other parameters.

Mark