2015 RT188 Evinrude 115 performance

[Bryanneely]

I’ve seen several post on props and motor mount position, but none of them helped. I just bought a 2015 RT188 with the Etec motor. It has a Viper 21p prop, mounted in the third hole from the top. It doesn’t matter if there are three people or two people or loaded, unloaded…can only get 42 mph GPS 5500 rpm’s through the nema system connected to my graph. Before I dive into this, does anyone else have the same/similar setup? If so is this all I can expect? What can I do to get the speed up to the numbers I’ve seen on other post? (45-47 mph) Thanks for any info!

[CincyGus]

A couple questions. What is spec top RPM for your boat? Are you there or are you a little shy of it? How much do you have loaded in all the storage in the boat? Tried lightening up and removing the things you don't need to carry every trip to reduce weight? Compression test on the engine is the first thing I would do before spending anything on different props or moving the motor. 7 Year old motor may be fine or may have lost a little and you can't tell if it's an engine or a prop/ mounting problem until you know the engines giving it what it should.

[GeauxTide]

Your prop is too tall and your WOT is 6000. I would suggest a 19 or 20. My numbers are 44.7 empty and 43.2 loaded at 5500 (WOT is 5750) and height is hole #3. The 4 Blade Spitfire made a ridiculous difference in handling and stern lift.

[Bryanneely]

I should have put this in the original. I tried a Raker 19p. It was slower. Handling is no issue. Rides smooth!

[Bryanneely]

I believe it is 6000 rpm. The motor only has 120 hours so wouldn’t think it was compression. Motor runs great! Boat was almost empty when I tried it out. With both the 21p and 19 p.

[gbsmallie]

I have a 2015 RT with a 115 etec, no jack plate. I swapped out the stock prop for a stainless 4 blade....cant remember exactly which one but i can look, and gained a couple mph. 42 is pretty normal top speed with my wife and daughter and dog, it will hit 47 now solo in the right conditions and temps but usually 45 is max with 4 blade prop at about 57-5800rpm. I hit 50 once going downriver with the Spring runoff moving pretty good lol. These aren't fast boats but you can get a little better than 42 if its worth it to you

[justsomeguy]

When I had my 2014 RT188 with ETEC 115 I was running an 18P Raker and solo 46, with a passenger 44. Viper isn't the fastest prop for the ETEC.