Prop size issues

[smitdog]

I have a 1972 16' starcraft holiday v-hull aluminum runabout with a 1995 70hp evinrude on it. The boat has a ton of power coming out of the hole but seems to top out quickly. I bought the motor used and I used the prop that came with it. The boat the motor was on was larger and alot heavier. I have looked at other thread asking simular questions and saw that there was alot of imformation needed to get the exact prop. I am just looking for a ballpark figure because I am unable to get alot of that information. I mainly use to boat for fishing and do not keep alot of gear in the boat.

 

[Knightgang]

Re: Prop size issues

what size prop is on it now? That will help in determining what you will need. Look on the prop and you w=should find numbers stamped in it like 13X19, 12X21, etc. This will give us a starting point....

 

[propper_advice]

Re: Prop size issues

We can give a solid recommendation if we know what size prop is on the boat, and RPM's at WOT. That should be enough to get you really close to perfectly proppped.

 

[steelespike]

Re: Prop size issues

It can be very bad for the motor to guess at the best prop.
At the least you could end up with poor performance and mileage
at the worse premature engine failure.
as suggested if you can get us the prop size (usually on the barrel or under the prop nut)Max rpm and speed. A tiny tach is reasonable and easy to install.Just read carefully the description A gps, borrowed, is excellent for speed.After testing you can still use the tach to help establish the best cruising rpm.