long shaft motor on short transom?

[imported_steelshot]

i was just given a 16'grumman alum semi-v with a transom for a shortshaft,the 25 hp is a long shaft motor and was apparantly used with the boat does anyone have knolledge of what kind of performance i can expect to encounter?my use is primarily duck hunting on a fresh water lake, also can anyone id my omc motor?j25rlcsa thanks in advance! dave

 

[rickdb1boat]

Re: long shaft motor on short transom?

Hi steelshot


It will work, maybe not perfect, but it will work. Might be a little slower than it could be and might tend to throw a little water up at higher speeds. Each boat has it's own characteristics on how it handles. That's a 1980 Model Johnson Long Shaft...

 

[Wiggy]

Re: long shaft motor on short transom?

Perfect is obviously have a short shaft motor on a short shaft transom but you'll notice little difference. I too have run a long shaft motor on a short shaft transom, only problems were slightly increased fuel usage, slightly reduce top speed and the motor hitting the ground under transport on a trailer (of course you can always tilt the motor, but that isn't recommended). Then there's the chance of hitting the bottom is obviously increased in shallow water with a long shaft on a short transom due to more motor sitting lower thatn the boat's hull.

I also had to tilt the motor more than a short shaft to get the boat up on plane.

But really, the differences are really that insignificant that it'll be fine.

 

[deerhound]

Re: long shaft motor on short transom?

Although my set-up is on my inflatable which is 8ft. 6inch long dinghy with 4hp long shaft (should be short) it works fine with similar problems as mentioned. JBD

 

[Bob_VT]

Re: long shaft motor on short transom?

You can get a bracket that will raise the outboard to the proper height. The question is ..... is the extra money worth it? It's your choice.

The other option is to rebuild the transom wood completely and make the new transom higher. Once again money is the question.

 

[Texasmark]

Re: long shaft motor on short transom?

About a week ago we addressed this same issue. Suggest you look

Mark

 

[Solittle]

Re: long shaft motor on short transom?

I run a 9.9 on a 12'er that way with no problem.

 

[steelespike]

Re: long shaft motor on short transom?

As has been said this will work though not very practical.
Certainly a waste if gas at $3= a gallon.
Just one inch reduction in lowerunit in the water can
mean a 2 or 3 mph difference at planing speed.Your going to be dragging 5 inches too much.

 

[imported_steelshot]

Re: long shaft motor on short transom?

gas mileage is not an issue ,i wait all year to go duck'n spend ton o money too.my island is about 2or three miles from launch just need to be able to get back in timely fashion will have to just try it if it constantly loses plane and cavitates then i have an old 9.9 short shsft that has'nt been used in 7 years or so in back of garage it'll be slow i'm sure. i was working on boat today lots of salt corrosian fix some but it's lost cause to bad i wanted a 16' painted mud brown like this one real bad i'll use this year and get rid in spring look for newer fresh water boat.

 

[hunterope]

Re: long shaft motor on short transom?

Guys.. Thank you so much for this post. You've addressed several of my issues with a 15 HP Force. Motor is in tip-top condition, Prop is in super good shape, but I wasn't getting a good top end out of it. Wasn't over reving (5300 to 5500 rpm)'s/ I was going to switch the prop and see if that helped, but in stead, I raised my long shaft up about 2 inches(the most I could get out of it ) Just below level with the bottom of the boat and I picked up almost 4 MPH and my fuel consumption went way down. I noticed a difference immediatly. If you can raise up your motor on a short transom boat, do it. Well worth the money if your looking to get the most out of your motor/boat combo.

Good luck and thanks gain.

 

[geordybass]

Re: long shaft motor on short transom?

(of course you can always tilt the motor, but that isn't recommended).

Why isn't it?

 

[Dale Speck]

Re: long shaft motor on short transom?

I had the same problem. I rebuilt the transom for about 12 bucks and my time. The 9.9 really isn't a bad option. If it is set up and tuned correctly it will surely surprise you how well it will push you up the proverbial crick.