Converting IO to OB?

[dingbat]

Re: Converting IO to OB?

that the bracket you are refering too? i am thinking of just taking my time and making a new bracket or catch tank that sits off my transom just to say hey i did it Iboats and give my review, it is scraps i will scrap the hull and by another out board hull. i am 21 so i have all the time in the world. but so far i ahvnt seen a review on someone who actually did it. it just get discouraged.

Don't get discouraged; go for it if you have the time and patients. Replacing a transom isn?t that hard and making provisions to mount an outboard is as easy as measuring up from the keel and making the cut.

Unless you have a high performance hull a bracket really isn?t practical. While giving the props better water to work in they can present problems in low speed backing maneuvers. When backing up you have to remember to trim the motor up to properly apply back thrust.

My boat has the option of a bracket (pictured below) that I choose not to purchase but in hindsight I probably should have and learned to live with it.

 

[erikgreen]

Re: Converting IO to OB?

Actually, in an IO relatively little force is borne by the motor mounts, which as you say are on the stringers. Almost no thrust force is transmitted from the lower unit to the motor - that would misalign the drive train and destroy it in short order pretty easily.

The torque of the motor and its weight are held by the stringers/motor mounts, but all the steering torque, thrust, etc from the motor is transmitted directly to the transom via the gimbal ring assembly.

Also keep in mind that most I/Os are higher hp than most outboards, and have more force to deal with. A transom that mounts a 400 horsepower sterndrive is going to be much stronger than one with a 250 horse outboard on it - because it has to be. The whole drive train will be cheaper, too

On a 17 foot boat with a 100 horse outboard how thick is the transom? I know mercruiser specifies a nominal 2 inch thickness of transom wood and glass just to mount the lower end inboards. Most people on this board who rebuild use two layers of 3/4" plywood laminated and covered with glass.

Erik

 

[Robj]

Re: Converting IO to OB?

Those outboard brackets look great. But do not forget your cg location. You may end up with a stern heavy boat that handles like crap. On that boat shown earlier, look at where all the structure is, the helm etc, close to the front to move the cg closer to the bow. On a larger boat, you can have two outboards hanging off the back because you have alot of boat up front to move your cg forward. I remember in my little tin can, we often put rocks up front to improve the steering. I would imagine the same goes for boats, you do not want them too stern heavy. I am sure there are design guidelines somewhere as to where the cg should be in boats. Maybe someone has this information.

Have a great day,

Rob.

 

[newbie4life]

Re: Converting IO to OB?

WOW...

But in a lighter note (no pun intended to the mother in law) everyone is correct. The stringers take alot more of the thurst force than the transom. i am embarking on this quest (maybe) with a 24' scarab hull. and the transom is nothing like that of my old 21ft well craft OB.

You darn right, WOW. Obviously, you've seen her.

 

[peacekeeper6]

Re: Converting IO to OB?

Another advantage of the big brackets is they are hollow and give additional floatation...

These are listed advantages from continouswave.com :



BTW, these babies aint cheap. Some people make their own out of plywood and many layers of glass.

that is a really clean set up, but i bet with some time and patience something like that could be manufactured onto the back of a boat. instead of paying a g or more for it.