Anyone specialize in SF 23 Inboard Specs?

[blunas2188]

I am wondering if there is anyone who owns or simply knows about the 23 foot SF inboard Seacraft. I recently bought an original potter built 23 footer - http://www.classicseacraft.com/SF23inboard.htm - that has a straight shaft. As of now I have a 1989 235 hp V8 gas inboard with a 1.25'' shaft. I am looking to re-power with a 200+ hp diesel. does anyone know if I would be able to put a bigger shaft, possibly a 1.5" instead of the 1.25"?

If anyone has any experience with this type of set up, help would be greatly appreciated. THANKS

[JohnB]

I have wrenched some on a friend of mines. He has a Savage with an inboard, 1989, probably the same engine you have.
I am not an expert on diesel's but my guess is you would have to put the bigger shaft in, which would include bearings, seals, and some other stuff. Those are not cheap.
You would probably have to change the propellor and transmission, and probably modify the engine mounts, unless you bought a diesel with the same mounting footprint.
Another thing I would watch closely is the balance. That motor, and the 100 gal gas tanks sitting in the back really have that thing stern heavy. We put the livewell forward, and tried to shift some stuff, but that layout just is tail heavy. A diesel usually weighs more, and I don't think any additional weight in that boat is a good thing.
That's just my opinion.

[Miles Offshore]

i think the 1.25" is probably fine as there were many inboards, i know of three/two sister ships of mine , that came with factory diesels. 1.5" would certainly be plenty and then some. i would think it would be fairly cut and dry replacing the stuffing box , coupling and strut. the line up being the most difficult part with the new strut. laser pointer should help with that

[joey]

You can probably get away with an 1 1/4 " shaft if you went with a stronger Aquamet 22 or like material, coupled to a higher RPM turning diesel like a Yanmar.The lower turning higher tourqe engines like the Cummins will definately require the 1 1/2" shaft.Also,be sure that if you put say a Cummins in that there is enough room under the boat to swing the larger wheel that it will need.I was having the same issues with a carolina boat that I had and I really,really tried to put a Cummins in her,but after alot of research it would of been just to much of a pain.Larger shaft,stuffing box,strut,exhaust,plumbing,etc.The Yanmar is a drop in for a 350 gas engine,same engine foot print,no running gear change,if you have 4" exhaust no change there,you will probably swing the same wheel that you have or one very close because the Yanmar turns about the same rpm's as a gas engine.I'm not crazy about a 3800 rpm diesel,kind of defeats the purpose to me,but a lot of folks swear by them.Good luck with your repower.