Prop pitch

[liver42]

I have a 22' pontoon, bought a 2019 mercury 90hp. Originally had a 13 pitch on it with no speed and hitting the rev limiter. Tried a 19 pitch 4400-4600 rpms at 18 mph dropped to a 17 pitch rpms went up to 4900ish but no top end speed increase. Should I try a 14 or 15 pitch? This was all done with just the wife and I

[Puto]

I don't know if I'm allowed to post a link, so my apologies if I violate TOS. I'm just trying to help the poster out a bit. If you haven't gone over the most popular video-watching site in the world and watched the videos on props by Family Marine in Wisconsin, then you should. PS-- Part of the two video's titles include "Prop" and "Be a hero, not a zero."

Fantastic primer on props. Each video is about 20 min, but the education is free and irreplaceable.

Hope this helps.

[wwind3]

I have a 20ft Lowe --90 Optimax. 27 GPS at 5800rpm. SS prop- 16inch pitch. Went to 17" --- rpm dropped to 5400 and no increase in speed--lost 1 mph I believe.

Strangely-my spare aluminum prop 16 pitch-same diameter is faster. 28 GPS-have hit 29 once. Go figger.

Bottom line--propping a pontoon boat is fun

18 mph seems slow even with a 22 ft--but maybe so--harder to get the bow outa the water I suspect. You are basically pushing a dumpster thru the water.

[liver42]

I've done a lot of research, will check out the video

[TheWhisker]

I'm thinking I may have to figure out something similar now that I've rebuilt my 'toon. I have only had it out once since the rebuild, and had very little time to test any WOT performance. The reason I'm thinking this is because the new layout has dramatically changed how it sits in the water. Previously it had a *very low* stern down angle in the water (so low that two separate times, people actually thought my boat was sinking). There's no water in the logs, by the way. It was just very rear-heavy with a lot of furniture, the gas tank, the motor, and two batteries all at the rear.

The new design eliminated most of the rear furniture except for two captain's chairs. The gas tank is now just in front of the transom, and the batteries are nearly mid-ship. In other words, far less weight back there. The result is the boat sits up much higher back there now and overall it's close to level with a slight stern pitch-down when sitting still. It is also lighter by several hundred pounds now because there's a lot less furniture.

So, next time I am out I am going to dedicate some time to running at WOT to see how the performance is. I'm a little concerned that it will not be bow-up enough and I may not be able to trim it enough to properly compensate and may need a different prop. Am I off in my thinking? 20' toon with a 90hp Yamaha 4 stroke.