placement of motor

[Papa G]

Does the motor on a johnboat have to be centered on the transom? I want to build up the tramsom so it will take a long shaft 15hp motor but I don't want to give up my short shaft incase I need to use it for a spare if the 15 hp gives out. I would not use both motors at the same time, just one or the other? It sounds like I want my cake and be able to eat it too. The build up for the long shaft will be bolted to the transom and would be permanent. Would I be able to mount the short shaft next to the bolted area without problems?

 

[BWR1953]

Re: placement of motor

Why not build up the transom for the short shaft with a notch, then add a cap that can be bolted on for the longshaft when needed?

-BWR

 

[Ned L]

Re: placement of motor

I would have to first ask, what size johnboat, and what size is your short shaft engine. I presume you would build up the transom in the middle so that your long shaft is on center, and only the short shaft would be offset those occasional times you used it. If it is a larger johnboat with a noticeably smaller outboard you may be able to get away with it (need further details though). In order for the boat to run straight with an offset outboard you will need to keep the tiller off to one side a bit, which will actually make the boat crab along at a slight angle (how much can only be determined by trying). My concern is when turning corners, the boat may tend bank unevenly (more in one direction than the other), and could conceivably result in a situation than causes it to roll over. This would be due to a combined effect of boat size, outboard HP and weight, how far off center it is, what weight is aboard (and where it is), etc. Again, need more details.

 

[tashasdaddy]

Re: placement of motor

add a transom elevator, then it could be removed.

 

[Papa G]

Re: placement of motor

Jonboat is 14 ft long 54inches at the center of boat from side to side. Weight on the 15 hp is 78 to 80 lbs. The build up is for the 15hp. Not sure I understand about the cap on the transom?

 

[BWR1953]

Re: placement of motor

Jonboat is 14 ft long 54inches at the center of boat from side to side. Weight on the 15 hp is 78 to 80 lbs. The build up is for the 15hp. Not sure I understand about the cap on the transom?

Like the red area in my pic below. Something that you'd have to make. Instead of a permanent mount like mine, you could just put in the filler with a bolt-on cap that can be installed when you have the larger motor to use.

-BWR