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davidpm 06-20-2013 08:57 PM

Epoxy screws
 
I just did something that I'm hoping will work.

I have an old beater sailing dinghy I use as a tender that has been dragged across rocks and sand for a few years.

It has a skeg about on inch thick and four inches deep.
The gel coat on the bottom of the skeg has been rubbed off for some time but I figured the skeg was a solid piece of wood encapsulated in glass so I didn't worry about it too much.

I was wrong the skeg shape is molded fiberglass no thicker than the rest of the boat.
If finally wore though and started to leak.
I glassed it up and figured I could glue a piece of aluminum to the bottom for protection. I bought 5200 but rather than wasting a tube of the expensive stuff I tried something else.

I drilled a few holes in the aluminum strap and counter sunk them just as if I was going to screw it on with flat head screws.
I then bedded the strap in thickened epoxy including the screw holes.
This makes an epoxy flat head screw which I hope will mechanically help the strap stay attached to the bottom.

I'll keep an eye on it.
Worst that will happen is that it will fall off.

Minnewaska 06-21-2013 06:38 AM

Re: Epoxy screws
 
Did you use epoxy that is meant to be underwater?

davidpm 06-21-2013 08:17 AM

Re: Epoxy screws
 
Quote:

Originally Posted by Minnewaska (Post 1047295)
Did you use epoxy that is meant to be underwater?

I used west system and plan on doing a very rough job of coating with gel coat.
http://www.westsystem.com/ss/assets/...2Polyester.pdf

I'm just using what I have on hand.
The boat is dry sailed anyway.

The way I understand it most epoxy is ok underwater but the underwater stuff will actually stick and cure better and faster.

Some new boats have vacuum bagged hulls with epoxy, but they are painted of course.

jimgo 06-21-2013 08:49 AM

Re: Epoxy screws
 
I'll be curious to see how this holds up. Please keep us updated!

BarryL 06-21-2013 10:41 AM

Re: Epoxy screws
 
Hey,

I had a similar situation with a old plastic WaterTender dinghy. After years of dragging it up and down the sand the 'skeg' wore though and allowed water to get between the outer and inner plastic. It still floated fine but got real heavy to drag up the beach. I got a few more years out of it by gluing a wood strip onto the skeg.

I tried your solution of epoxy and an aluminum strip but the aluminum was too brittle and broke off. The wood lasted longer but it was hard to get a water tight seal with epoxy.

My ultimate solution was to by a new Watertender 9.4 for $500 (when on sail). I figured it would last 20 years so I would be ok. It was stolen this spring but that's another story.

Good luck,
Barry

pauloman 06-21-2013 11:35 AM

Re: Epoxy screws
 
the only difference with underwater epoxy is that it uses curing agents etc. that don't react with the water during cure...

epoxy is sort of a medium hard plastic - not very strong or scratch resistant. The epoxy you used is known for it's brittleness.

bond strength is a surface area issue. - you want to get max surface area - ie. the bottom of the al. strip.

one common fix is to mix sand into the epoxy and spread over the worn areas. When that also wears down you mix up a bit more epoxy and sand and reapply.

paul

davidpm 06-22-2013 12:41 AM

Re: Epoxy screws
 
Quote:

Originally Posted by pauloman (Post 1047427)

one common fix is to mix sand into the epoxy and spread over the worn areas. When that also wears down you mix up a bit more epoxy and sand and reapply.

paul

I like that idea.
Sort of like an ablative paint.

davidpm 06-22-2013 12:44 AM

Re: Epoxy screws
 
Quote:

Originally Posted by BarryL (Post 1047397)
Hey,

I had a similar situation with a old plastic WaterTender dinghy. After years of dragging it up and down the sand the 'skeg' wore though and allowed water to get between the outer and inner plastic. It still floated fine but got real heavy to drag up the beach. I got a few more years out of it by gluing a wood strip onto the skeg.

I tried your solution of epoxy and an aluminum strip but the aluminum was too brittle and broke off. The wood lasted longer but it was hard to get a water tight seal with epoxy.

My ultimate solution was to by a new Watertender 9.4 for $500 (when on sail). I figured it would last 20 years so I would be ok. It was stolen this spring but that's another story.

Good luck,
Barry

This is a fiberglass dinghy so I'm hoping the epoxy will work better.
The aluminum is supported full length and if anything is too soft not too brittle.

I'll probably do what you did, fix it until I can't then buy something else.


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