Boat seriously underpowered w/9.5 HP Johnson

[Lundman A-14]

As I suspected it would be after trying it out this week at a local reservoir,...my 1973 Sea Nymph 14R is seriously underpowered with
the little 9.5 HP Johnson that came with it. As I have stated before,
my boat is rated for 25 HP. Even at full speed with the wind to my
back,she still could not get the boat up on plane. The boat needs at least an 18 HP motor all the way up to her max. rating of 25 HP to perform on such a large body of water like Salamonie Lake that lies within two northern Indiana counties;..Huntington and Wabash. The motor almost put me to sleep going at such a slow pace.

 

[Chris]

As I suspected it would be after trying it out this week at a local reservoir,...my 1973 Sea Nymph 14R is seriously underpowered with
the little 9.5 HP Johnson that came with it. As I have stated before,
my boat is rated for 25 HP. Even at full speed with the wind to my
back,she still could not get the boat up on plane. The boat needs at least an 18 HP motor all the way up to her max. rating of 25 HP to perform on such a large body of water like Salamonie Lake that lies within two northern Indiana counties;..Huntington and Wabash. The motor almost put me to sleep going at such a slow pace.

I would have thought it would plane with a 9.5. Have you tried moving some weight towards the front?

The other thing you could check is the compression and see if it's low. Maybe you're not making a full 9 1/2 ponies.

-Chris

 

[Lundman A-14]

I would have thought it would plane with a 9.5. Have you tried moving some weight towards the front?

The other thing you could check is the compression and see if it's low. Maybe you're not making a full 9 1/2 ponies.

-Chris

I moved the aft anchor to try and balance the weight,but that did not help at all,Chris! The boat still porpoises even at W.O.T. A buddy of mine on another site feels that I am indeed under powered and as a result,the motor burned more gas since it had to work harder. He feels that I should move up in power,...though he did not indicate how far,...
but feels if I did have a bigger motor it would not burn as much gas since it would not have to work as hard and I can back off the gas to save fuel.
I think at least an 18 HP motor would work quite well if not the full 25 HP
that my rig is rated for.

 

[Chris]

I moved the aft anchor to try and balance the weight,but that did not help at all,Chris! The boat still porpoises even at W.O.T. A buddy of mine on another site feels that I am indeed under powered and as a result,the motor burned more gas since it had to work harder. He feels that I should move up in power,...though he did not indicate how far,...
but feels if I did have a bigger motor it would not burn as much gas since it would not have to work as hard and I can back off the gas to save fuel.
I think at least an 18 HP motor would work quite well if not the full 25 HP
that my rig is rated for.

I think I misunderstood.

Originally, I thought you mentioned you couldn't get the boat to plane because of a lack of power.

Are you saying the boat is porpoising? As in the nose bouncing up and down at WOT?

-Chris

 

[Lundman A-14]

Not lack of power,Chris,...just too small a motor for a boat that is rated for 25 HP. The bowl does not bounce up and down,...it stays up,period!
Ever hear of www.iboats.com? I have a posting on their site under the "Johnson& Evinrude Troubles and Repair"board titled "Underpowered".
You might want to check out and see what those guys have to say.
Most agree that I am underpowered and have too small a motor on that boat of mine. They say I should have AT LEAST an 18 HP motor on my rig.

 

[Chris]

OK. I gotcha now.

A couple of things you could try...

-Try adjusting the manual tilt pin to the lowest position and see if helps the boat plane.

-Move some weight forward, the gas tank is a good item to move there. If the fuel hose isn't long enough, just get some hose and lengthen it.

-Make sure the motor is making 9 1/2 H.P. Best way is make sure it's tuned up and that the compression is decent.

If you can get it planed out, it will probably run quite a bit faster than you think, but with it plowing along with the nose in the air, you'll be going no-where fast.

-Chris

 

[Lundman A-14]

Went out on the boat today and I think I may have discovered the problem,Chris. On my motor,right below the choke lever/knob,there is
a slow speed adjustment. I found that to be set a tad too rich which I
believe would not allow the motor to reach much speed above idle and
not allow the motor to get the boat up on plane. I turned the"slow speed
adjustment" all the way down and that made a huge difference. The motor now at least gets the boat on plane,but she does it slowly,...holeshot is
way slow and the motor still has to use more fuel to do it. It sucked down another 1/4 tank today after two hours run time. Still,she is a tad under
powered,and could use a bigger motor. With just me in the boat,I think a
15 HP motor would get her up on plane faster and use less fuel since it
won't have to work as hard as that little 9.5 HP motor.

 

[Chris]

Hey Nymph,

Glad to hear you made some progress.

Do you have one knob on your motor or two?

-Chris