1963 Evinrude Sportwin 10hp bogs with two people in the boat

[Zrbush]

I've got a 1963 evinrude on a 12 ft V-hull. It works great with just me in the boat, getting up to about 20mph, but with another person in the boat I can only get 8-10. It just feels like it's not getting to full throttle. I've tried messing with the trim pins, and the mixture knobs, but nothing works.

Does anyone have any idea what this might be? The only other thing I've noticed that might be related is there sometimes is like an oily water mix around the cavitation plate and prop after use.

Any help would be appreciated

-Zane

 

[CMOS]

Are you suggesting there is a PROBLEM with the motor, or are you just unhappy with the performance?

How big are these "two people"? How much fuel weight and other gear do you have on board?

Those speeds don't sound too out of the ordinary.

CMOS

 

[Zrbush]

I'm thinking there might be a problem. Perhaps it's weight distribution, but having another guy who weighs 140 soaking wet slowing the boat down 10 miles an hour. I've only got a battery trolling motor and a tackle box or two. I'm wondering if something can be done to tune the motor to work better under load or something.

Thanks,

-Zane

 

[KMixson]

Could be a few things. First, it could be normal since there is more weight in the boat it may be just enough to keep it from planing causing the motor to not reach its rated RPM since it is having more resistance from the water not moving fast enough by the prop. I have noticed there is a limit of weight and when you exceed that weight the performance can drop drastically. It may plane and run fine at one weight and then add 15 pounds and it refuses to move. The oily water may be a result of the motor not being worked that hard before and creating forces on the prop shaft and seals causing it to leak.

Second, it may be the weight and balance of the items in the boat. Move things around and see if that helps.

All in all I would bet my first guess would be the most probable cause.

 

[CMOS]

Have you tried trimming up the motor one notch to see of that helps?



CMOS

 

[lckstckn2smknbrls]

Have you done a compression test on the motor?

 

[user 20022]

It's all in the weight distribution and the prop. More weight and you'll need a second prop to compensate the diff. The hole shot won't be the same as with one person nor will wot but it will be close enough.

Sent from my LGLS991 using Tapatalk

 

[Pappy]

A 12' boat has very little lifting surface compared to a 14' or better. Added weight really takes a toll on a smaller hull. Run the boat super light and see what the engine is capable of then run it again with the weight you are questioning. Am thinking you will find your answer.
I just ran the Suwanee River this weekend with several boats and antique/vintage engines. On one of the longer runs there was a fellow with a 1956 15hp Johnson on a 12' Alumacraft. Single person at about 180 plus a battery, safety gear, extra 6 gallon tank full of fuel, a spare tire...and a cooler. Performance was pretty dismal and not up to his expectations. I was asked about the engine. We unloaded the boat and he was happy with the engine.
In your case you may find that a 14' or longer hull with more planing surface will actually perform better than the smaller hull.

Here is a photo of the rig I mention.