propeller for a Johnson 50hp 2 stroke

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J

jeff K

I have a 2003 26M with a Johnson 50hp 2 stroke and I get about 16-18 mph(GPS)max. If anyone has this motor and is getting better maximum speed what propellor are you using. Also I wanted to get a less expensive Sunshade. It's supposed to be 10 degrees here on saturday and I don't want to put up my mast and sail in the snow to measure the height I can make the sunshade/bimini without hitting the boom. Does anyone know the height of the sunshade that MacGregor sells or how high the boom is above the helm or cockpit floor. Thanks. Jeff K. Michigan
 
T

Timm Miller

RPM's

Are you using a tachometer? What is the WOT of the motor?........what rpm's are YOU getting at WOT? I would be more concerned about getting the motor up to WOT then top end speed. The 20+ mph you're thinking about isn't going to happen. No replacement for displacement.
 
N

Norm

Hope this helps

This may be comparing apples to, well, a differnt kind of apple, but I have a 2003 Johnson 50hp 4-stroke on my 2002 26X. I get 20mph max (GPS) @ 6200 RPMs using a 11-3/4" X 10 pitch prop. Thats on calm water no wind. The "M" is a little heavier and has a rounder bottom so 18mph sounds about right to me. And as Tim said, the important thing is that your getting the correct RPM's at WOT. For the Johnson 4-stroke that would be between 6000-6400. I don't know about the 2-stroke.
 
B

BW

operating range

Jeff, just in case you didn't know, the WOT RPM range on a 2 stroke is less than a 4 stroke. 2 stroke is normally 5500 on the top end. The 10 pitch prop with a 11 1/2 to 12 inch diameter is probably the most common for the 50 horse used on Macs or at least the 26X. Your motor needs to be able to turn at least 5000+ at WOT.
 
Jun 7, 2004
3
Macgregor 26X Mayo, MD
Try bigger

I have a 26X with a 1996 Johnson 50 2 stroke. My prop is 12 inches or bigger. I easily get 22-24 mph flat out with no ballast. With ballast I can still get 18-20.
 
Jun 5, 2004
72
- - Pensacola, Fl
Operating range

As BW and Timm noted, it is extremely important that your motor be able to turn the prop at least 5000+ rpms at full throttle. If not the motor is lugging and wearing out very fast. When choosing a prop both the diameter and the pitch must be considered. It really doesn't mean much to say "I have a 12 inch prop" without also noting the pitch. As long as the prop doesn't strike the shaft housing (cavitation plate) that prop will work. However the pith on such a prop would probably have to be well less than 10. I use a 11 7/8 X 10 pitch on my 50 HP. I have a 10 X 12 pitch as a spare and use it sometimes if I am cruising under power for a long distance at low rpm.
 
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