Prop education

[joshadurham]

Rickinfarmington just posted asking about which prop to run for a certain application, so I decided to ask for a schooling on props. I’m new to this whole outboard hobby. I just recently moved from west Texas, where there is no water, to east Texas where there is water everywhere. I just stumbled upon a CD-13, 2 months ago, and have learned a lot and had a blast. So props are something I’ve often wondered about. I’ve heard of weedless props, prop pitch (which I understand somewhat since I grew up in an aviation family and am a pilot), all different kinds of props. I’ve had my cd-13 on three different boats, and they all acted different obviously. How does a person pick a prop to run, for a certain application, and where do you find them? Does it make a noticeable difference?

[frankr]

If you are thinking in terms of your CD-13 the prop that came on it from the factory is suitable for the average boat it is likely to be used on. Sure you can spend some dough trying to tweak that extra MPH out of it, but will you actually be able to tell? Probably not. One exception might be if the stock setup is almost, but not quite able to plane it. If that is the case, you may be able to get it up on plane with a prop change and see a noticeable difference.

[joshadurham]

Makes sense. I plan on getting more larger 50’s Johnson outboards in the near future. Does it become more important as the horses increase? And what the heck is a weedless prop? How does that work?

Thanks

[frankr]

The swept-back blades are supposed to shed the weeds instead of winding them up around the prop. Doesn’t work though, at least not down here in the hay fields we call lakes.

[r-c]

As in racing the prop makes a big difference. However the choice of props for your engine is limited as most of the lower HP engines are. The OMC prop is 8 x 7 1/4 2 blade weedless with no other options. There are some Michigan made props but all are out of stock. They offered: AM 430 7 3/4 x 6 1/2 BR 3 blade, AM 431 7 3/4 x 6 1/2 Al 3 bld, AM 433 7 3/4 x 7 BR 3 bld, J300 8 x 7 1/2 AL 2 bld standard replacement and JWC 5 7 3/4 x 6 1/2 AL 3 bld weedless. Whtch your swap meets to find.
Weedless means the swept back blade design is suppose to let weeds fall off the prop. Like Frank says doesn’t alwalys work. Your transom height makes a difference between boats. Not all of the smaller boats actually have a 15" transom. Measure and get shim sticks to adjust higher.

[legendre]

The way I see it, the advent of the ‘weedless’ propeller was more of a marketing breakthrough than anything else.

If you think about the fact that ‘weedless’ propellers have been "new & improved" more than once, it should start to sink in.. heh.

This said, some designs are better than others, I’m sure.. and as ever, YMMV.

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