Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

[nhblock]

As detailed in this thread, I picked up a beautifully-running 1966 Sears/McCullogh Ted Williams 7.5 for my 14' fiberglass dinghy. Now that I have the fuel line issues solved, it's on to cosmetics.

As you can see in the pictures, there are some cracks in the cowl, and even some chunks missing. I came up with (what I thought was) a solution, which was to make patterns and cut some pieces out of plexiglass, then epoxy them in to the missing parts of the cover. However, the pieces are so small that I just ended up shattering the plexiglass (and sliced open my palm in the process).

Is there another, more flexible material that is resistant enough to heat/water that I can use to patch these holes? Or am I just not cutting the plexiglass correctly?

 

[mrcrabs]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

My friend I'm with you on this, I have a briitle old Gamfisher hood thats been heat damged and has UV cracking,
I youtubed plastic welding and found I could spend $$$ or use the soldering pencil method...trenching and folding each side, which works but the one factor is the old plastic....it still brittle even after a repair.

I asked Todd Ashly Peters about it since he's the best resto man I have seen and he suggested after the repair to use a coat of resin inside the hood then resin and cloth for structural support,
if all else fails use the personal message system and contact me, I have a 63 Sears Elgin branded McCullough hood that needs a good paint job and one or two minor cracks repaired,

Good luck and keep us posted.

 

[nhblock]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

Thanks for the solidarity on this... I'm going to head to Home Depot and see if they have any alternate repair materials for the missing pieces. I have an Ace in my neighborhood where I do most of my hardware shopping but they don't have a very large raw materials selection. I'll let you know what I come up with.

The cracks I'm going to try 2-part plastic epoxy. I've heard of plastic soldering but it sounds... difficult lol.

Hopefully I can get this repaired myself -- that's a good suggestion about the cloth/resin on the inside for support and longevity. I'm planning on doing a full teardown and resto of the fiberglass boat this summer while the waterways are shut down for the NATO conference in Chicago, so I'll add that to the list. If I can't get this cowl sorted, I'll take you up on that offer!

 

[todd ashley peters]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

hey block, hows things.

ya plexy glass sucks to work with and is not itself uv resistant. not sure what kind of plastic is in that hood but it aint plexy. skim a small bit off of an inconspicuous spot. burn it with a bic. smell will tell. if its just a plasticy smell(oh blow it out before you smell), its likely polyethelene. if it has a waxxy smell then its polypropelene. both of these are called thermoplastics(formed by melting). if it refuses to burn or burns only with some coaxing, its likley an earlier polymer. these you cant weld at all.

i would try to use some material that is as similar to the hood as you can find, even if you are going to glue or epoxy. if you weld it the pieces have to be an exact materials match, and if a filler rod is used it must also match the parent material.

i would use a high viscosity epoxy like mas or west\east systems, but just to get by until you convince yourself that you would have been much better off to get ahold of mrcrabs, the hardware kind will probibly do. rough up the edges of both real good, and anywhere that the 6 oz cloth will hit.(at least 1" on both sides of the seam) hold the pieces togeter with duct tape from the outside. goop the epoxy on with a paintbrush, then lay the cloth into the epoxy. with more epoxy on the brush, roll it over the patch to soak it in good. dont use 5 min for that job. dont rush it, one section at a time and let it cure well before you mess around with it. then when your done the inside do the bodywork on the out side to match up. good luck.

 

[nhblock]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

Thanks for the pro-tip, Todd. I've decided to leave it be for now and create a mold, then cast a reproduction in fiberglass. I'm thinking it will be about the same cost as buying a replacement, plus some good experience in molding/casting. I'll shoot it in gelcoat when I do the resto on the boat.

The slice on my hand from mucking about with the plastic is just starting to close up, so I'll stick to something a bit less dangerous.

I did some searching and found this guide to creating a mold (warning: PDF), which I think should work.

 

[todd ashley peters]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

ya that looks good be real nice if you could get it one peice. let us know how things go. if you are like me you'l sick with until ya get it.

lol

I'll try anything twice.

 

[nhblock]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

So I did some more searching for a more pliable material and came up with a flexible plastic sign, like a for sale sign you'd put on your house. It ended up being easy to cut and bend, but still decently thick. So I made up some templates and went to work with the plastic epoxy. It worked great.

It doesn't look pretty, but I'll do some sanding once the epoxy cures. It's certainly not perfect, but it will have to do until I get all the materials together to cast the whole thing and re-make the hood in fiberglass.

 

[F_R]

Re: Repairing plastic cowl on a 1966 Sears/McCullogh 7.5

Run off a few extras of those hood castings. Everybody with one of those motors needs one.