I have a 20' pontoon with a 25 HP 2017 Etec, and I am trying to determine the correct prop for the combo. With a 11x7 4 blade at WOT it hits 6000 RPM's for a max speed of 9-10 MPH. With a 11x9 3 blade at WOT it hits 5100 RPM's for a max speed of 11-12 MPH.
When I called Evinrude hey were no help. The services rep told me they o not provide technical support and to call a dealer. I have talked to several dealers and get no help form them...they tell me to talk to Evinrude.
When researching props, I noticed that most props for the 15,25, &30 Etec are 10" in diameter and not 11"
So, on pontoon, should I be using a 10” prop vs an 11” prop? My objective is not fast hole shoot with my pontoon but a good top end speed with a good load performance.
Thanks in advance,
06-05-2019 09:59 - edited 06-05-2019 10:03
A 25 HP on a 20' pontoon boat may be considered a little under-powered, thus the low speeds. Your engine specs call for the motor to be propped for full throttle in the 5500-6000 rpm range with a normal load which makes the 11 x 7 prop in the ball park. You may also want to try the 10 x 11 SSP - #765176 - to see how that performs.
Prop diameter is designed by the engineer to be most efficient for the pitch and the speed of the boat. As a rule of thumb,for the same engine, a lower pitch is for slower boats and usually has a larger diameter than the higher pitched props.
With a pontoon boat you always want to prop at the top of the rpm range because as you add more people and gear, the engine will still be in its recommended operating range.
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