Prop testing on my F90

the-little-B

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Got some more numbers trying a couple more props. Excuse my chicken scratches I call notes!

The boat came with the Solace 13.5x15 and all I'm able to get out of it is 5000 rpm. The speed is great and it's hit 26.5 mph in good water but the rpm's aren't where they need to be. Overall I'd say this prop feels the best except for the fact it can't get past 5000 rpm.

The Yamaha 13.5x14 "K" prop suprised me and was disappointing. It performed ok as far as no cavitation etc but only 4850 rpm's? That didn't make sense to me. It doesn't follow the rules for pitch changes.

The Yamaha 13 5/8x13 ran right at 5959-6000 rpm and is only a couple mph off of the speed of the 15 pitch prop but seems almost lethargic from 4000 rpm on up and feels like it's slipping a bit.

All this was with 3 people on the boat in what would be normal conditions around here. A bit of a breeze and some chop and other boat traffic. The boat is a 20ssx , two 25" tubes , full underskinning , and the motor in the lowest mounting position. I'm going to try raising the motor and do it all over again to see if anything is gained or lost. One last thing...the local prop shop said they thought the 13 pitch should be good for my set up but the Yamaha props are not cupped. He thought cupping the 13 might put things where they need to be.

Thoughts and comments from the more prop savvy here are welcomed! IMG_20180701_142304.jpg
 
I have a 2018 21SL with 90hp Yamaha. It has a 13 5/8 x 13 prop on it. I can hit between 28 and 29 mph at 6000 rpms. That is with my wife, son and myself. I had a 21 year old worn out Suncruiser w/40hp Johnson and the best I got was 13mph at 4800 rpm's. I am very pleased with my new Benny.
 
Banditz,
Yamaha prop? K series prop or talon? What position is your motor mounted at?
 
Yamaha prop. I believe the motor is at the lowest position. I don't even have to mess with the trim when I'm out.
 
GPS app on phone. Has always been right on with my cars digital speedometer
 
I'm using the Humminbird gps. I'd think that would be pretty accurate as well. I know it's not a speed boat! But a guy still wants everything out of what he has...
 
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