Transom too short

[freeisforme]

I picked up a free boat today, it appears to be a 1960 Starcraft Voyager.
It belonged to a guy that restored Corvettes, which explains the new plywood and glass deck, and what appears to be a solid transom laid up with fiberglass throughout. It was in the water when I found it and I even got to test drive it before I took it. It ran great, did nothing wrong at all. The boat is solid, handles well, and the Tohatsu motor ran flawlessly. The only issues I found at all weren't realized till I got it home and started really going over it.
The deck is unpainted, it just had a huge piece of carpet laying over the new deck, (I tossed the carpet), the stern light is missing its lens, and the most serious, the motor is too long for the transom. It's got a 20" shaft length 40hp Tohatsu engine on a 17" tall transom. The anti ventilation plate is about 4" below the lowest part of the transom.

Keeping in mind that the boat runs and drives fine, what would you do? Raise the motor with a bracket? Find a short shaft motor? Built up the transom or shim the transom on top a bit? (Keep in mind that the motor is a clamp on style, with no bolts, so I'd only be able to add maybe a couple of inches of spacer to the top of the transom, and at that I don't like that idea much.

How strong is an all fiberglass transom? I've seen and done a few poured transoms, but this guy appears to have laid up many, many layers of mat and built up a 1.5" transom. In doing so, he's also made the top cap of the boat permanent, as the new transom and splashwell is now all one piece.
The boat uses threaded plastic through hull fittings, I was able to remove those and see that the transom is solid. I can stand on the lower unit, there's no flex at all. I'd sort of rather keep the motor weight over the transom and not add any leverage by using a bracket.
I also don't suppose I'd find any cheap running short shaft remote control motors too easily either, at least none in this size range.
As it stands right now, I have nothing invested, and it floats, runs, and has all it's paperwork.
What would be the worst case scenario if I just run it the way it is with the motor being too long?

 

[ezmobee]

Re: Transom too short

I'd do this http://forums.iboats.com/showthread.php?t=321432

 

[Woodonglass]

Re: Transom too short

EZ took the "Thread" right outa my keyboard!

I'm just sayin...

 

[freeisforme]

Re: Transom too short

I was thinking of doing something like this, take two pieces of aluminum angle, make a 4" riser panel, and bolt the angle aluminum so as to keep the new riser panel flush with the original transom. Then I'd like to add wear plates to both the inside and outside of the transom to protect the hull and add some support.
Being that the boat is cable and pulley steered, setting the motor back may affect the way the cables align with the pulleys? The system works fine so I hate to mess with it until it needs to be done, then maybe I'd convert to teleflex steering. The cable, pulleys, and springs all look like new right now, so I don't see it being any safety issue for some time yet.

I've never been a big fan of short transom boats, adding to this transom all the way across would also help make the boat safer in my opinion, especially in following seas.

 

[tmcalavy]

Re: Transom too short

Depends on how well you like/dislike the Tohatsu. The only effect of a longshaft motor will be less top end and kinda sluggish in turns...also more exposure to underwater obstacles.
Try raising it with shims under the motor/transom clamp...raising it only 2 inches might make a difference...depends on hull shape/design. That boat would look/ride sweet with a 58-62 OMC big twin on it...plenty of those around in short shaft configuration. Post some pix, we love eye candy.

 

[redfury]

Re: Transom too short

Both ideas will work as long as the thrust from the motor is being distributed on the transom evenly, and that the new transom board isn't going to "let go" in any way, shape, or form. Last thing you want to do is hit something underwater and watch the motor disappear behind the boat.

Usually, even with a clamp on motor, there are bolt holes in the mount you can use...my little 25 Johnson is clamped and bolted to my boat ( keeps anyone from just "lifting" the motor, if you know what I mean.

 

[freeisforme]

Re: Transom too short

There are only two bolt holes, they are both pretty high up on the motor bracket. They may or may not be low enough to go through the original part of the transom if I add a riser.
The one thing I like about the Tohatsu is that it's really light, far lighter than those older big twins I suppose. This motor weighs less than my 30hp Evinrude.
The lower unit design is a bit different than on an American motor, even though its sitting on a 16.5" tall transom, and the motor measures 21 7/8" from the clamp bracket down to the anti-cavitation plate, the anti-cavitation plate sits only about 2 inches below the boats bottom when checked with a straight edge.

I'll try to get a few pics if it stops raining before dark.

 

[freeisforme]

Re: Transom too short

After some messing around with the Tohatsu motor, I found that it needs to come up almost 7" to put the anti-cavitation plate just above the bottom of the hull. The motor measures 21.5" from the inside the bracket to the top of the lower fin.
My thinking is that anything I do will be nothing short of a rig and at that I'd be adding weight.
I pulled the Tohatsu off and found a short shaft Mercury 500 to replace it with. The Merc is older but has perfect compression and runs good. I do need to deal with some bad wiring under the hood on the motor but that's easier to deal with then making big structural changes to the boat. I still may add some sort of transom addition just to prevent any backwash over the transom since it's only 16" tall, but that can be rubber or something light.
The Mercury is heavier than the Tohatsu but about 40 or so pounds I guess, but since its a quick fix for the boat, on it goes.

I'll either sell the Tohatsu or save it for another boat.

 

[ezmobee]

Re: Transom too short

Sounds like a good solution to me. Old Mercs often have issues with deteriorated wiring so nothing out of the ordinary there. I'm sure it will be a good motor for your boat.

 

[freeisforme]

Re: Transom too short

I was going to just order a harness from CDI for the Merc but figured that the motor will not likely ever leave this boat, I just tossed the plug on the control harness, made up two new batter cables, and ran the wires direct. I replaced the individual wires, picked up a new rectifier at NAPA and wired it in with some spade connectors and new wire. The only thing left to deal with is the rotten wires on the stator. The trigger is new, so at least those wires are good. The wires from the stator are so rotted they fall apart when touched. I just need to figure out how to re-solder on new leads to the stator without damaging the stator. I actually like the direct wire method since it takes the battery connection out of the side plug, the control harness end was a bit worn too so I'm sure I eliminated any future issues there. I found a rubber grommet to fit the hole and glued that in place with some 5200, and ran the wires inside that through three separate smaller holes all sealed with 5200. I wrapped all the external wires in harness convoluted tubing and tied it securely to the bracket. I soldered and heat shrank all the terminal ends so they should be permanent.
Other than the wiring being rotted, the motor looks like new. Its newer than I thought, the number turned out to be a 1977, which matched the date stamped on the starter. I can't wait to see how a 15', 500lb glass boat moves on the water with the Mercury motor. It was pretty quick with the too long Tohatsu motor, I'm betting the right length motor will be an improvement. Of course, the HP rating change of 1984 may mean that I really didn't gain much in HP at the prop?