Outboard conversion w/out a bracket??

[kdc808]

Anyone convert an i/o to an outboard without using an extension. Maybe making a splashwell?

 

[Scott Danforth]

3 easy steps

sell I/O boat for small pile of cash
empty wallet onto pile making it bigger
buy OB boat for medium pile of cash.

or do a bunch of engineering to develop a transom for an outboard, and make a custom splashwell.

many projects have been attempted. I do not know of any that were finished.

 

[dingbat]

Anyone convert an i/o to an outboard without using an extension. Maybe making a splashwell?

That splash well isn't the issue. Lots of boats out there running w/o splash wells

It's all the modifications required to the transom to mount and support the outboard. Basically remove and replace in it's entirely.

 

[Lou C]

I have seen some of these done over at www.thehulltruth.com
they usually use some kind of transom extension though and the inside of the transom has to be extensively strengthened due to the different forces and greater weight on the transom vs an I/O. It is very expensive, time consuming and is usually done on a boat with high resale potential, not mass market boats like most of us have. Keep in mind beyond that the high price of outboards themselves, unless you don't mind buying a used one. There are real benefits to it but a lot of unknowns and a lot of 'glass work.
If I were buying a newer boat there's no question I'd go outboard, but convert an older (even is valuable) boat? I don't think so.....

 

[mickyryan]

here is what you would need to do
1 remove all existing i/o equipment
2 gain acess to the transom , personally id decap boat to make that possible,
3 unskin inside of boat and remove existing wood from transom leaving outer skin
4 install new wood proper thickess or make a form and pour in a pourable type transom after coverring the original hole for i /o
5 install knee braces from transom to floor for strength
6 glass it all in and then you ready to figure out proper cut on cap to allow for installation of outboard,
7 cut transom to proper height for long or short shaft outboard, id try to go with long that way you dont have to worry about water coming over back of boat.
8 finish off top of transom and the cap to make it look as nice as possible .
9 install outboard after predrilling holes for mounting
10 install all rigging and cables
as you can see it is a task that isnt easy, can it be done?, of course, are you gonna stick with it till end ? thats a question only you can answer.
this is based on good stringers if not good stringers you might as well gut boat cut floor and stringers out and redo those at same time . you will need about 30 gallons of resin to do the job most likely if stringers floor and transom.

 

[mickyryan]

btw i dont think you can beat a ride of a inboard or io because the weight is in the bottom of hull, ease of maintence the outboard wins hands down,

 

[kdc808]

btw i dont think you can beat a ride of a inboard or io because the weight is in the bottom of hull, ease of maintence the outboard wins hands down,

Thanks for the detailed breakdown. If the boat was bigger I'd definitely keep the inboard. Outboard would free up a lot of space and yes ease of maintenance is a big thing.

 

[stresspoint]

iv seen a few done without a bracket , owners have re engineered the transom to suit outboard .
personally i would stay below 100 hp if i was to go that route.

 

[kdc808]

Boat is a 222 cuddycon. Most likely put a 175 suzuki on it

 

[airshot]

Would never attempt that changeover on a fiberglass boat, way to much messy work and expense and you would never get a return on your time and effort. Now if it were an aluminum boat, that might be a different story as their resale is far greater, but...you will never recoup your expenses. Find the boat you want and replace the one you have.

 

[mickyryan]

22 footer is a lot of work but doable if its the boat you want to keep and yeah id go big on the outboard thats not a small boat lol

 

[mickyryan]

some pics of said boat would go far to help us assist with the "plan"

 

[stresspoint]

in most cases the build structure of a outboard hull as opposed to a IO or inboard is different, transoms for example are not as solid built on an IO as there is no weight to support .
steering cable is another thing to consider , hence one reason for a tub or bracket for outboards ,the tub also acts as a support structure to relive stresses on the cap join.

i would suggest a bracket set up for your boat with that motor , strait to the point , you go right ahead and re invent the wheel if that's your thing.

as i posted a small HP on a small boat you can get away with what you want to do , a 22 footer with a 175 , i hope you don't want to do blue water boating .

 

[Scott Danforth]

there is a reason that two identical boats, one I/O and one outboard. the outboard will have 100hp as its max rating, the I/O can have 2000hp.

the outboard is trying to pry the top of the transom off the boat
the I/O is pushing the boat forward from the bottom of the transom and the stringers

 

[mickyryan]

Thing to remember also is stress points, as others have men tioned, as you change structure of boat think of where stress will be I'd also argue the rear corners of a outboard transom are probably reinforced as well since that's a transfer point of stresses

 

[matt167]

Outboards are built with a transom angle. Do I/O’s have the same angle? I’ve never checked. The tilt pin/ position would negate it a bit if it was different tho

 

[tpenfield]

Anyone convert an i/o to an outboard without using an extension. Maybe making a splashwell?

Save yourself the design challenges and agony of reworking the stern/transom. . . get yourself an appropriate sized bracket. There will be enough work in just modifying and reinforcing the transom.

 

[dingbat]

The bracket is used to help provide additional floatation given your moving the center of mass of the propulsion system back roughly 24-30” from it original design location

FWIW my outboard transom is reinforced with aluminum bracing