didn't get an answer

[bobjoe1]

Several days ago I posted a question and did not get a response. The ? was , I have a 1989 Evinrude 40hp motor mounted on a 17 ft. Lowe aluminum boat with a 8 hp trolling motor. I was curious as to what the max rpm's and top speed would be, if all things were perfect. Currently I max out at 5000 Rpm's and 31 mph. Does this sound normal, bad good ot otherwise. Thanks. Also I do not know what pitch the prop is.

 

[Solittle]

Re: didn't get an answer

I think you should be getting 5500 rpms out of your engine at WOT. Take your prop to any prop shop and they will measure what you have and re pitch it or sell you a new one. If you drop an inch in pitch you should pick up about 500 rpm.

 

[bob johnson]

Re: didn't get an answer

sounds nromal, but you do want your rpms to max out higher, like 5500

But i think you would have to go more than an inch down in pitch to pick up 500 RPMs!!!

I thought the rule of thumb was 1"= 200 rpms

you might need to go down 3" in pitch!!

if you do, be carefull if you lighten the standard load...you could start to run up into the high 5,000's...

i doubt you will get much more speed...2 mph if you are very lucky with the same rigged boat

good luck

bob