Prop for my 1978 evinrude 75hp

[shawn.54]

I have 1977 starcraft capri 15 it is in good shape for age. it is powered by 1978 75hp evinrude had this same post in winter but now have more numbers to share speed 30 mph prop michigan super prop in great shape 13 1/4 x 17 rpm 5400 12 gallon fuel 3 adults 1 child 320,225,130,90.
this combo preforms well can turn wheel all way left or right she turns sharp and only looses about 150 rpm's. this makes tubing fun. the only complaint is front raises alot on take off and if most weight is not up front it stays up. stay up with 320 and 90 in front. My question is do i change props or try to level boat seem like it wants to go faster the closer to level it gets. I don't know??? would pich change slow it down/ thanks for input in advanced


shawn

 

[dazk14]

Re: Prop for my 1978 evinrude 75hp

Those 3 cylinder loopers do not have a lot of low end torque. So getting rpm's up is a must and normally a 15" pitch is used if there is any watersports involved. You can run the rpm up to 6000.

3 questions.
Does your existing prop have vent holes at the leading edge base of the blades?
Do you have power trim?
Do you have a planing aid aka "Doel-fin" etc.?

A 4 Blade 15" pitch Solas Amita4 for $111 delivered from iboats will probably be ideal. You may lose a mph on top end.

Post back

 

[shawn.54]

Re: Prop for my 1978 evinrude 75hp

no power trim no vents no hydro foil was thinking about smart tabs have a 14 x 13 prop will try that. watching tach of course.

 

[dazk14]

Re: Prop for my 1978 evinrude 75hp

That's fine. For testing the 13" pitch, you can run that motor to 6300 for 20 seconds, or so, without fear of throwing a rod.

Is the motor somewhat trimmed in? A 15" 4 blade will provide better acceleration and be stern lifting and a common solution in boats similar to yours. A foil is also very common in that application.

Are you close to planing?

 

[shawn.54]

Re: Prop for my 1978 evinrude 75hp

how to put this the power is there iboat jumps out of hole hits 4000 quick then front starts coming down slowly and builds rpm's at decent rate have been in over proped boats that take forever to wind up and are easy hold back this boat not like them when pulling me on tube (320) does not loose power only 100-150 rpm's i'm asking a lot out of this little rig it will pull me skiing too. it just needs that little push over top. gets most speed and take off in lowest setting.