Thread: 3 or 4 blade prop?

Just thought of this, how far in the water do you have to back the trailer, to launch? If it's not very far, look at your springs/axle. Is the axle overslung or underslung? If it's overslung, measure to see how much it would raise the trailer, if you underslung the axle, that should keep the prop from bottoming out. If axle is already underslung, look at the spindles, are they straight from the axle? Angles up or down? Mounted on top or bottom of the axle? If they're angled up, or mounted on top, again measure, and see how it much it would lift the trailer if you flipped the axle.I did this (had the opposite problem your having) on a previous boat, the trailer sat to high. It loaded and launched like a dream after that.

4 blade is best, especially on boats with smaller hp engines. My boat with a 40 hp tiller came with a 3 blade, it became a totally different boat when I changed to a 4 blade.

Advantage is more "bite" meaning it gets on plane faster, you are able to stay on plane at lower speeds, and it lifts the stern more which helps if all of your batteries/fuel tank/weight are in the stern of the boat. A 4 blade typically provides better fuel economy as well.

People talk about loss of speed between a 3 blade and a 4 blade, with a 40 hp you're only talking maybe 0.5 mph difference.

Solas Amita 4 is the one I like, has a pressed-in hub, and is about $100. The original prop was a 15 pitch 3 blade, I changed to a 13 pitch 4 blade.....I tried the 14 pitch 4 blade but it was too much pitch if I had more than just myself in the boat.

Originally Posted by DoyleAlley

I once had a 19' Aquasport DC with a stepped hull. Even though it had a 2-stroke 150hp Evinrude.....However, I did loose about 1-2 mph on the top end.

That loss would be expected for a 19 ft boat with a 150 hp

For a 16 ft with a 40 hp, the loss is barely even noticed, maybe a 0.5 mph at most.