There is another option, seeing you already have a reinforced transom: An outboard. It would be far lighter back there, which would help plane off and trim, plus you cna carry more weight aft. Lots of good used ones out there at the moment, costing as much or less than a new outdrive.

You'd need an extended mounting bracket that you could fab up of aluminum or purchase. Longer cables will work the throttle and shifter from your present controls, and a new steering cable can be adapted fairly easily. Best of all, modern outboards are reliable and--if something goes wrong--easier to remove than an inboard.


Something to consider.

Jeff

There'd be so much less weight back there a 200 hp OB would move it easily. As for twin engines, OBs are very reliable nowadays.


Jeff

PS: There's a video out there of a guy who converted a Marinette to OB power. Went great with far less than 200 hp, and I think it was an old 26 footer. Anyone have the URL?

Holy Crap!
I could drop 6 to 10k on an outboard!

I was impressed with a MercTrans II sterndrive I saw, I think the TR/TRS are simliar...to bad the lower housing was cracked. The thing was a tank! Don't know if parts are available for something like that but I would guess that I would have a whole lot less labor into replacing a sterndrive than I would hanging a bracket and pulling my engine for an outboard.

Still thinking this one over...I'm planning on it as winter work.


Thanks

That old Mercruser drive (with the conventional marine transmission inside the boat) is the BEST outdrive setup I've seen: smooth shifting and durable. Too bad that it cost way more than the slam/ clunk designs that took its place.


Jeff

As a fixed prop/transmission seems the most reliable way to go I now have to figure if I have the room.

Does anyone have info on how far from the engine do I need to make my thru-hull for the shaft packing?

I have a single GM engine and have no idea how much room behind my engine the tranny and the prop shaft will need.

OK Doc,
6' less 1-1/4" gives me 70-3/4" for the shaft.
Now how much do I figure for the tranny and u-joint from the engine to the shaft?

Tranny and u-joint? The stock setup has the engine tilted back about 14 degrees so that the crankshaft and tranny are in line with the shaft, which attaches to the tranny with a flange.

If you use a jointed shaft, you should use CV joints unless the crankshaft is parallel with the propshaft. If you do this, you should provide a thrust bearing at the front of the propeller shaft so as not to put that load onto the flexible joint. This setup is common in Europe and I did it on my 28'. I will make up a drawing if that would help at all.

But, the wonderful simplicity of shaft drive is lost.

I don't think a V-drive is going to give you what you are looking for:

Pros:
1. It allows you to put the engine closer to the transom

Cons:
1. Reduced efficiency due to added drivetrain drag
2. Makes adjusting and changing packing very difficult
3. Makes transmission removal much more difficult
4. More expensive to purchase
5. Increases the installed height of the engine
6. Moves the boats center of gravity rearward (harder to plane / increased minimum planing speed)
7. Adds (some) drivetrain noise
8. More difficult access to prop flange

IMO, the most reliable automotive based engine setup is good 'ol detroit iron running through a 1:1 velvet drive. Though I love my Mopars, as far as parts cost and availability, a small block chevy is hard to beat.

For overall reliability and ease of repair, and single 200-250hp outboard is hard to beat, though the cost can be a bit much.

If I were in your shoes... Stick with the I/O, keep up with maintenance, and enjoy many years of trouble free service. Though I am partial to VP drives (A 280pt is hard to beat for simplicity and durability), the Merc drives are pretty good too, though ignition cut out was a dumb idea, and the impeller IN the drive was also not a great idea. The VP units have no ignition interrupt and use a much more robust dog clutch. They also use an IB drive plate instead of a rubber coupler, and have an IB style impeller pump...

-Shane

OK, it is probably not relevant but I promised a picture of the flexible drive that I used on my old 28'. These drives are common in Europe, and you can buy them made of marine materials, costing several thousands. There are two advantages: First, the engine can be mounted flat (horizontal) so that a taller engine will fit. This is important if one is repowering with an in-line diesel. Second, the engine can be mounted on very soft mounts (there is no thrust to absorb) and will therefore not transmit vibration into the engine bed.



The propeller thrust does not go through the engine to the engine mounts, so a thrust bearing is needed. I got an industrial one and mounted it in line with the stuffing box, mounted through a hole in the web of an I-beam section that was secured to the stringers (engine bed) on either side. I used two split collars around the shaft to transfer the thrust (one for forward thrust and one for reverse thrust). I didn't want to rely on the grub screw in the thrust bearing itself.

The Euro flexible shaft is big bux, but such shafts are used in front-wheel-drive cars. I got one with two flanges (most have a flange at one end and a spline at the other) from a Cadillac Eldorado and machined up an adapter for each end. The flexible shafts will not insulate electrically so one of the adapters has to provide electrical insulation, as well as insulating the thrust bearing from the I-beam section.

This worked OK for me, allowing me to mount my tall 4-cylinder Perkins. I ended up bolting the engine directly to the mounting rails, didn't seem to matter.

Yeah, I was pretty proud of how that turned out. It looks so neat and well-thought-out, but actually it was a summer of running around looking for parts, then making stuff that didn't work and had to be thrown out, then running across something good in the junkyard. Jeff, I am sure you have been there.

The lady who bought the boat wanted no part of diesels, and restored her to a stock 318. I gave the flex shaft, for a fit check, to a guy who said he would give me some money for it, and haven't seen hide nor hair of him since. And, the photos I took are missing and I can't find the negatives.

I did find the other source: www.pythondrive.com The shafts are a little shorter than I remember, but I these will let you mount the engine level and couple to an inclined shaft, as I did.