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ContinuousWave: Whaler Performance
1982 15' sport w/ 1982 Evinrude 75 Supersport
|Author||Topic: 1982 15' sport w/ 1982 Evinrude 75 Supersport|
posted 04-22-2001 11:04 PM ET (US)
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!
posted 04-23-2001 08:01 AM ET (US)
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
posted 04-23-2001 08:05 AM ET (US)
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.
posted 04-23-2001 01:01 PM ET (US)
Thanks! What prop size would you reccomend?
|Tom W Clark||
posted 04-23-2001 01:06 PM ET (US)
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?
posted 04-23-2001 01:42 PM ET (US)
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.
posted 04-23-2001 06:22 PM ET (US)
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.
posted 04-23-2001 10:28 PM ET (US)
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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