I/O SF to Outboard, no bracket

Sf20 · #1 04-12-2015, 11:19 PM

I am considering doing something similar to what Frizzle did with his 1974 Sceptre with my 20sf that is currently i/o. I am kicking around the idea of converting it to outboard, but would like to do it without having to use a bracket. Do you think that bracing the transom by adding a few knees connecting the transom to the hull would be sufficient to support an outboard? I know that the SF hull was also made for an outboard, so I thought that I could just maybe modify the transom of my i/o to resemble the transom that they made for outboards so that it could structurally support an outboard. Advice and thoughts?? Is this doable without a bracket? Is it advisable without a bracket, or will it cause stress to my hull?

flyingfrizzle · #2 04-13-2015, 08:09 AM

Quote:

Originally Posted by Sf20

I am considering doing something similar to what Frizzle did with his 1974 Sceptre with my 20sf that is currently i/o. I am kicking around the idea of converting it to outboard, but would like to do it without having to use a bracket. Do you think that bracing the transom by adding a few knees connecting the transom to the hull would be sufficient to support an outboard? I know that the SF hull was also made for an outboard, so I thought that I could just maybe modify the transom of my i/o to resemble the transom that they made for outboards so that it could structurally support an outboard. Advice and thoughts?? Is this doable without a bracket? Is it advisable without a bracket, or will it cause stress to my hull?

It all depends on how strong the transom is. If you are going to replace the old wood and re-core it then no worries. Knees are good for extra strength but not necessary. The knee I added on my 20' is a little big and excessive but I tend to run the crap out of my boats in ruff water so I added it. Part of the reason I made it as large as I did was so I could mount my fuel/water separator to it. Having knees don't hurt anything except just adding a small amount of extra weight but worth it to me for the strength. I rather over build than under. The only part that will be tough is converting the engine box area to a splash well for the motor to tilt up into. You can copy the outboard model liners or do something similar.

shine · #3 04-14-2015, 10:15 AM

It will most likely work without much modification to the transom. How thick is the transom core?

Sf20 · #4 04-15-2015, 10:31 PM

Frizzle- I was planning on replacing the transom if necessary and potentially notching it down a few inches.

Shine- the transom is about 1-7/8 inches thick, I don't know much about how fiberglass is laid, but I'm guessing the core is about 1-1/2 inches thick or so.

Sf20 · #5 04-15-2015, 10:37 PM

Is this a project a fiberglass novice could/should undertake? I have a friend that does fiberglass work that I know would be willing to offer advice/guidance, so I wouldn't be flying totally blind.

flyingfrizzle · #6 04-16-2015, 11:02 AM

Quote:

Originally Posted by Sf20

Is this a project a fiberglass novice could/should undertake? I have a friend that does fiberglass work that I know would be willing to offer advice/guidance, so I wouldn't be flying totally blind.

If you have basic skills you can do it! Lots of help up here. Read as many post in the rebuild section as possible and ask questions. Its not rocket science but a dirt job. Prepare to get itchy.

Two 3/4" marine plys or either marine foam like coosa will be plenty strong with a good layer of glass on each side.