Curved Transome

[DsledgeR]

Hello all,

I'm restoring a '65 Glasspar Marathon. It has a curved transom, which I've Seacasted.....man that stuff is very cool. At any rate, it previously had a '98 Evinrude 60HP mounted on it, and it's a strong runner. I want to put it back on, but here's my dilemma:

The gap between the curved transom/straight mount of the engine are what caused the water intrusion to begin with. Is there a relatively easy way to shim the space, or build a mount that goes between the engine and takes up the curve of the transom???

 

[Bob_VT]

Re: Curved Transome

Welcome to iboats.

I guess you could use a piece of 3/4" plywood and a belt sander. Get it to match the curve then seal it up with fiberglass and cloth.

How much curve are you talking about?

Pictures??

 

[DsledgeR]

Re: Curved Transome

Thanks for responding Bob,

At the top bolting points, maybe a 1/4 inch, if that. At the bottom bolting points, around 1/8". I was thinking instead of wood, using a corian cutting board and sanding it down on the curved side, the hard part being getting the right shape.

Was also wondering if there was a thinner, heat-shapable material where I could bend one to the curve, mate it to a straight piece, and fill the void between the two thin sheets with epoxy/filler, and glass as an assembly.

I'm out of town right now, but will post pics next week when I get back.....

 

[reelfishin]

Re: Curved Transome

The first curved transom I redid was on a Glaspar Tacoma, their a pia to say the least but the fix I found was pretty simple, and may have even helped performance a bit?
I did the transom using layers of 1/4" plywood, glass mat, and epoxy, then to solve the curved transom/flat motor issue, I made up a setback plate using four pieces of 4" angle iron, and remounted the motor, then a 40hp Mercury, later a 60hp Evinrude. The boat ran and handled great, the offset brackets kept the motor from distorting the transom, the bolt holes could be permanently sealed, and the set back bracket allowed me to fine tune the motor height for the most top end. I sold it two years ago, the current owner is still running it that way but with a larger motor, a 90hp Evinrude as I kept my motor when I sold it.

Seacast is the way to go, but if your not digging out the floor, damming up the Seacast pour below the deck is a challenge as is building a curved support to hold the weight of the wet resin when you make the pour. (The inner hull skin on mine was nothing but a single very thin layer of woven mat). My thoughts were since no matter what I did, it would most likely outlast me, I went with the wood since to me, it was easier in that I didn't need to built up the wood supports and wouldn't have the flow control issues I could picture with the Sea Cast. I was happy with the results of the fix on mine, it was a better boat all around, at least it seemed that way when I was done, if nothing else, it was peace of mind. My only complaint was that the boat was too small which lead to my selling it.

 

[Bob_VT]

Re: Curved Transome

Do not use cutting board for two reasons.....

No strength

NOTHING will adhere to it (except the smell of a cut onion )

 

[DsledgeR]

Re: Curved Transome

Reelfishin....any old pics of that offset plate you built? I know you sold the boat, but thought I'd ask. I already Seacasted the transome, and it turned out great.......solid as a rock.....unfortunately, a curved rock!

Bob.....As for using a piece of corian......It would be between the motor mounting surface, and the curved exterior surface of the transome, with four bolts run through it as an assembly to hold it in place, so not sure I need anything to stick to it, or are you referring to the sealant for the holes?? Maybe use a piece of Starboard??? Just want it to be fairly permanent, so don't want to use wood.....

 

[reelfishin]

Re: Curved Transome

I don't think I have any pics saved but all I did was take four 12" pieces of 1.5" angle aluminum, bolted them together to make a Z channel, then made up a 12x14 or so motor mounting panel out of two layers of epoxy laminated 3/4" plywood. This was then bolted across the two aluminum brackets.

(Tashasdaddy here has a few good pics of one he built that's very similar but with the intention of raising or lower the motor).

Check out this thread: http://forums.iboats.com/showthread.php?t=321432&highlight=jack+plate

The purpose is different but it may work for your situation quite well.
I've found that moving the outboard rearward is usually a win/win situation performance wise too. By moving the motor back no matter how much, you get the prop into 'cleaner' water. Often allowing the motor to be run a bit higher than normal, yet still able to properly cool. This reduces drag on the lower unit overall.

Most don't ever even notice the misfit between a flat motor bracket and curved transom and just tighten up the bolts and go with it. But the right answer is to make that a tight fit that don't stress either the motor or transom.

 

[DsledgeR]

Re: Curved Transome

Thanks....that looks like it'll work! Probably easier too......I've got a couple of friends good at that kind of stuff, and will show them the pics......