Overpowering a small aluminum

[mew]

I found a grumman sport boat on craigslist (like the one in the link), and it seems like it would be great for fishing shallow waters and exploring river islands. By all accounts they are built really well. The only problem is that it is only rated for 7HP, and the only motor I have is a 1964 18HP Evinrude Fastwin. I really trust that motor - I've worked on it and have grown attached to it - and I'm wondering if maybe I could get away with using it on the Grumman....

My concerns are transom strength and getting ticketed. I'm not too worried about going too fast because I'd just back off on the throttle if need be. The other concern is if I got a new 7HP, it might not be able to push me, a couple friends, and cargo up river.

Do you have any experience with putting a large motor on a small boat? Any help is greatly appreciated!


Grumman Sport Boat

 

[Howard Sterndrive]

Re: Overpowering a small aluminum

Some boats are fine, others are unpredictable at best.
I have a 12 foot cartopper rated for 7.5hp that goes like this:

5HP= dragging anchor?
6HP= dragging anchor?
7.5HP= ok, planes with one+dog...not fast
9.9HP= death machine- can't even begin to maintain control- like some sort of picklefork dragboat on steroids

That one in the picture with an 18? I think not.

 

[mew]

Re: Overpowering a small aluminum

So... it sounds like maybe it's a bad idea to put an 18HP on this boat. I a bit worried about 7HP not being powerful enough, though. I wonder why they rated it so low. Maybe it isn't meant for use on swift rivers.

 

[JB]

Re: Overpowering a small aluminum

That is not a planing hull. It is more of a canoe on steroids, a displacement hull. 7HP should be plenty, 18HP more than double too much.

That hull begs for a '70s JohnnyRude 6HP and an operator who respects its limitations.

 

[Bondo]

Re: Overpowering a small aluminum

So... it sounds like maybe it's a bad idea to put an 18HP on this boat. I a bit worried about 7HP not being powerful enough, though. I wonder why they rated it so low. Maybe it isn't meant for use on swift rivers.

Ayuh,.... Welcome Aboard,.... JB is Right, that's a square-stern Canoe,...

No Way I'd try over-powerin' it,...

You'll spend more time Up-side-down, than boatin'....

 

[Home Cookin']

Re: Overpowering a small aluminum

that's a great motor you have and I understand why you love it.
that's a great boat, too.

just not together.

the 18 will be way too heavy, then you need 6 gallons of gas, too. And motors aren't happy if they aren't run at high speed often.

put the 18 on a wide body 14' square bow jon

 

[rivermouse]

Re: Overpowering a small aluminum

Fried you need to find another boat. I wouldnt trust that boat any place but a quiet pond even with the correct engine. Go get yourself a real boat unless you love swimming..

 

[Frank Acampora]

Re: Overpowering a small aluminum

Oh, No, No, No, No! Even I whose motto is "Too much horsepower is never enough" Would not put that Rude on that hull.

It is (as said) basically a square back canoe. Note that shipping instructions state it must be shipped with a certified canoe hauler.

Buy that boat and buy a set of paddles to go with it.

 

[gm280]

Re: Overpowering a small aluminum

With as many 14 foot flat bottom Jon boats listed all the time, I'd spend the money on one of them and you and your friends would enjoy lots of memorable times on any body of water...safely too...

 

[lakelover]

Re: Overpowering a small aluminum

I wouldn't even think about it with that hull.

 

[Solittle]

Re: Overpowering a small aluminum

Lawyers would love that combination - -

 

[Jeep Man]

Re: Overpowering a small aluminum

Keep lookin' for a real tinny.

 

[Krichbourg]

Re: Overpowering a small aluminum

For what it's worth... I have a square stern canoe with a 4hp motor. My boat is an Old town Predator. It's rated for a 5 hp. On my boat, the 4 is more than enough. Even with two grown folks in the boat, I don't run it wide open. I think a 7 will push you fine. I love my little setup. On a calm day, I can go anywhere on almost no gas. If it's not calm, she stays on shore. Good luck.

 

[robert18hp]

Re: Overpowering a small aluminum

So... it sounds like maybe it's a bad idea to put an 18HP on this boat. I a bit worried about 7HP not being powerful enough, though. I wonder why they rated it so low. Maybe it isn't meant for use on swift rivers.

I have the 1964 18hp on my 1979 aluminum mirrowcraft 12ft. I love it! Feels like a small jet on the back. Lol. Without another person in front of a counter weight, it takes a little time to plane out. But it sure is fun! It's a strong motor and you have to be careful with the tiller steering. But I wouldn't go back to a smaller motor now.

 

[Bob_VT]

ONCE AGAIN PLEASE do not open old threads This one is over 10 years old