ideas on where to start with prop for 55hp Evinrude on 16.75 ft Alumacraft

Can'tFishEnough

Petty Officer 3rd Class
Joined
Apr 19, 2011
Messages
86
Hi all, I was wondering if anyone might be able to help me with a "where to start" question... The motor has never been on this boat before so I don't have any RPM/Speed data for you at this point. It came off a pontoon boat, but the guy who sold it to me said he didn't think that was the prop on it but just one the stuck on temporarily when his father-in-law gave him the motor.
This motor has a 12 1/4 x 15 prop on it now, but it's pretty damaged on one blade tip and at least one other is a little bent and will at least require about $55-70 work at my local shop to restore. If this one can be fixed that would be great, but I'd like to have an idea where to have them set the pitch while it's in there if it needs to be changed, to save a little bit of $.

So, do I need to get it out and run it as is first? with a chunk about like one forth of a quarter (same diameter side to side and about as deep as 1/3 to 1/4 of a quarter) or is that asking for trouble? Would it actually tell me anything about what prop would need to be on in good condition?

Other option- my local shop sells turning point props and I think Michigan wheel (do those also have a separate/ interchangeable hub) I maybe could get the hub and then the middle range prop and go from there? Then get the 15pitch prop on there fixed later when I have a better idea of what I need.

Or look online for used ones or something.

For background, if it helps with boat performance to work backwards from load of/in boat:
With a 25hp Evinrude and its current 11x10 prop (fixed up to that from my local shop) gear ratio of 12:29 listed in OMC service manual (guess that's like 2.42):

--with about 500-650 pounds of people on board (mix of kids and adults) two deep cycle batteries trolling motor and 6-8 gallons of gas max, I'm running about 5200-5400 RPM & 20mph (gps speed) within about 100 pounds doesn't seem to really affect it much speed wise (maybe + or - .75 mph depending on wind etc).

-- alone and lighter on fuel maybe 2-3 gal (with a little throttle left) I'm at 5500 rmp & about 25mph

-- nadaguides has boat listed at 563 pounds and current 25hp motor at 123 pounds and the 55hp at 187

Thanks for your help.
 
Last edited:

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Use the present prop lightly loaded get us the wot rpm and gps speed.Don't worry about a repair at this point.
 

Can'tFishEnough

Petty Officer 3rd Class
Joined
Apr 19, 2011
Messages
86
OK. Thanks. Wasn't sure if that was safe or not. Will be a bit since I'm waiting for more parts to show up in the mail. Be Back soon I hope.
 
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