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Author Topic:   1982 15' sport w/ 1982 Evinrude 75 Supersport
masbama posted 04-22-2001 11:04 PM ET (US)   Profile for masbama   Send Email to masbama  
I convinced my buddy to "go whaler". We found a 1982 15' sport w/ 1982 75hp Supersport Evinrude engine. Stainless steel prop-we DO NOT know what size, pitch, etc. Here's the problem-It won't get out of the hole! It is like starting a manual transmission car in 2nd or 3rd gear! I think it may be the prop; when in neutral the engine revs fine! After a while it will get on plane and move along. It has a custom tank under the seat, battery and cooler kept behind the seat. I have a '77 Montauk w/ a 1990 60hp Johnson-doesn't go fast but gets up "outta da hole" just fine. Think hard experts and please reply! Thanks!
jameso posted 04-23-2001 08:01 AM ET (US)     Profile for jameso  Send Email to jameso     
Prop size should be marked on prop somewhere maybe on hub behind lock nut? Also how far is engine in water, do you need to raise it? I have a 15 with a 50 HP OMC that will knock your socks off out of the hole and run 36+ with light load. That engine should really perform!!
Thanks Jim Armstrong
jameso posted 04-23-2001 08:05 AM ET (US)     Profile for jameso  Send Email to jameso     
Might also "weigh" the boat,,don't need scales just put her in the water and look at the water line, my 15 with engine, battery fuel ect. sits high with the outer chimes almost at surface of water,,,but I doubt that you would have enough water in hull to cause problem,,,but maybe if it is all in the stern? Just thinking aloud.
Jim Armstrong
masbama posted 04-23-2001 01:01 PM ET (US)     Profile for masbama  Send Email to masbama     
Thanks! What prop size would you reccomend?
Tom W Clark posted 04-23-2001 01:06 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Almost certainly a prop with way to high a pitch. A 17" pitch prop should be about right and the boat should do well into the low 40's at WOT. By the way, what is the RPM at WOT?
goldstem posted 04-23-2001 01:42 PM ET (US)     Profile for goldstem  Send Email to goldstem     
There is probably something wrong with the motor.
It takes NO power to rev an engine in neutral.
how does it sound? kind of a low growl??
your probably running on 2 rather than three cylinders.
when my 115 evinrude looses a cylinder (from 4 to 3) I know right away from sound and feel. since this motor is new to you you don't know what it should be like. but a decently running 75 on a 15 should get on plane no matter how badly propped.
where2 posted 04-23-2001 06:22 PM ET (US)     Profile for where2  Send Email to where2     
Background: own '85 15' BW Sport model with '85 70Hp Johnson.
If you and your buddy are fairly big guys, say 225lbs each, then you've probably got a 13-1/4"x19" SS prop on that 75Hp engine. I have the same prop, and also a 13-1/4"x17" aluminum. If I load my boat with 3-4 friends in the 150lbs and under weight range, and go skiing, I can't get the boat out of the hole with the 19" pitch prop. If I drop to the 17" pitch, everything is great until I go out in the boat solo and I'm pushing just over 6k RPM WOT.
I've been tinkering with drilling vents behind the blades on the 19" prop to make it more versatile (since switching props back and forth is no fun). I've currently got atleast 1/4" holes behind each blade on the 19" pitch prop, and it is somewhat better. I'm still probably going to carry along the cordless drill next time I go skiing and see if I can get to the point where I have enough ventilation to get out of the hole, but not so much that I get slip on plane.
Anyone, other than me ever, consider drilling holes in the prop like Merc uses on their high HP ocean models. The various restrictor plugs only cost $5 a set. (This is my backup plan if I get the holes TOO big in my 19" SS prop).
BTW, my whaler will run 49mph WOT with the 19" prop, which is what the boat originally came with. The 17" pitch works better for pulling up 180lbs skiers on a slalom. Unfortunately, top end is only low 40's with the 17" pitch. Trade-offs...
OMC props list the part #, diameter and pitch under the retaining washer, so you have to take the prop off to find out what you have. Typically, when a prop has been "reworked", they'll stamp it around the hub somewhere, although YMMV.
masbama posted 04-23-2001 10:28 PM ET (US)     Profile for masbama  Send Email to masbama     
Thanks! We will pull the prop and find out the size; then we'll get the GPS out and find the true speed.

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