Topic: Enough power? – Antique Outboard Motor Club,Inc

This topic has 18 replies, 13 voices, and was last updated 6 years, 10 months ago by garry-in-michigan.

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June 15, 2017 at 3:21 pm #7338
mikeg
Participant
I have a 16′ tiller steer fishing boat, power is 1963 28hp Evinrude.
New carb kit, Ignition, good compression.
Boat is 420lbs, battery in rear, fuel tanks in front. With me (200lbs) this boat
has a hard time getting up on plane, top speed is 17mph.
I’ve tried a couple different props and tilt settings. Is this all I should expect?
I do have a 35hp, but would need to convert to long shaft.
What do you think.
Thanks, Mike ,Buffalo,NY
June 15, 2017 at 3:35 pm #59727
RICHARD A. WHITE
Participant
Lifetime Member
Have you looked at your USCG tag for rated hp of that particular boat?
should be back on the inside of the transom.

http://www.richardsoutboardtools.com
classicomctools@gmail.com
June 15, 2017 at 4:13 pm #59731
chinewalker
Participant
US Member
What are you running for a prop? Boat is fairly light. Those old 28s are good pullers. Might help if you drop down a notch in prop pitch to bring the RPM up. Akin to dropping down a gear when going uphill while towing a trailer.
June 15, 2017 at 6:04 pm #59733
hmai
Participant
I have a 25 hp bigtwin with a similar boat. 16ft utility. I am a very large guy and it doesn’t matter what i have in the back of the boat it will do high 20’s almost 30. It will plane the 16ft utility at 2/3’rds throttle. Have you made sure it is throttling up all the way? Long shaft on short shaft transom etc.
June 15, 2017 at 9:45 pm #59742
phil-b
Participant
After a run are both plugs dry? My first outing with my first outboard was only firing on one cylinder. Testing that the spark jumps 20 thousandths on the plug in open air wasn’t enough: in open air you need to test with a quarter inch gap, and the spark should be blue and have an audible snap.
June 15, 2017 at 9:50 pm #59743
mikeg
Participant
Boat is rated for up to 40hp, long shaft motor on long shaft transom.
It has never sounded like it’s "winding up". What should I look for to increase RPM,
besides prop?
June 16, 2017 at 2:06 am #59757
retiredoz
Participant
US Member
What are the specs on the prop you’re running now ?
June 16, 2017 at 2:30 am #59758
hmai
Participant
This is my 7.5hp, but same concept. Under the flywheel/magplate you will see a roller riding on a 1/2 moon. I.believe u want it to ride as far left when fully advanced without going off the plate. On the start position it should just barely touch on the plate.

Is the motor original to the boat? You may have lost a 8th of a inch off the prop without knowing it. A prop shop should be able to tell you and recommend the proper pitch for tour boat.

Both plugs firing and looking ok? You can get a bad condenser.

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June 16, 2017 at 2:45 am #59759
auldscott
Participant
US Member - 2 Years
Definitely does not sound like you are getting all 28 hp. I have an 18 foot utility, 460 lbs empty, that would do 20.3 with a 15 hp Yamaha with one aboard.

Lots of good advice here – check to be sure that at wide open throttle, the throttle butterfly is horizontal. The throttle and spark linkages could be out of whack. Also, be sure the neutral/reverse throttle stop is properly adjusted.

Angle, transom height, propeller conditon (not diam and pitch) can all have an effect, but I think much more is involved here.
June 16, 2017 at 2:59 am #59760
outbdnut2
Participant
US Member
Going to a short shaft motor for your short shaft transom should get you at least another 5 MPH – you are essentially dragging a 5 inch club through the water. I’ve seen blocking the motor up the thickness of two paint stir sticks (about 1/4 inch) give a 35 HP motor another 2 MPH on a lightweight 14′ aluminum runabout. Gas mileage will increase too.
Dave
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