Removing Dynel/epoxy sheathing

[Patrick Miller]

I'm sorry if this topic has been covered before, I didn't have much luck searching the old threads. As well, I haven't been active on the forum for over a year.

Anyway, I have a lovely little 20' wooden sailing boat which I've done quite a lot of stripping out to return it to its only sound feature - its hull. So the decks, house and beams have all gone, as have the floors. What I have now is a well built carvel hull of Oregon (Douglas fir) attached to (I think) spotted gum ribs with roves and rivets, sitting on (and I mean that literally with no floors) a backbone of spotted gum and a lead ballast keel.

What started out as refurbishment has ended up in a rebuild. When I'm finished I'll have a boat that I intend to "dry" sail from a cradle. The hull was Dynel sheathed with epoxy resin many years ago, long before my ownership, perhaps when newly built. The sheathing has been patched, sometimes badly, over the years, but generally it has done its job well of keeping the water out.

But as the hull is now in a shed on my farm, and I'm in a mood to get rid of extraneous stuff, I'm looking for folk with experience of getting lots of Dynel and epoxy off fir. I know from trying to remove plywood that was epoxied to my fir deck beams that it's no use trying to separate the two.

Why am I thinking of doing it?
* I don't need the sheathing to keep the water out because the boat won't be kept on a mooring.
* It wasn't part of the original design (and now that I have the drawings I'm making a bit of a fetish of reinstating the designer's intention).
* It adds weight - albeit where it doesn't do much harm.
* I'd like to see the planking from the outside.
* The sheathing, while soundish, needs a lot of work in patching and fairing, particularly around the gunwales.
* Time is not an issue as I see a project of some years ahead.

At this stage I'm thinking that if I proceed I have a lot of CAREFUL grinding/sanding ahead of me. But maybe there are some of you who have done a similar thing and can give me the benefit of your experience.

[Howard Sharp]

I don't know that this would work, but you could try heating the epoxy/dynel to the point where the epoxy would let go, using hot air, or maybe steam from a wallpaper stripper. After all, epoxy is supposed to be strong enough "unless you intend to boil your boat". Maybe now's the time to try boiling your boat!

[Bob Cleek]

Howard's close, but no cigar. Use a heat gun and a sharp scraper. Epoxy will soften under a heat gun. Expect a nasty job of it, but at least it isn't fibreglass. The glass irritates skin like nobody's business. BTW, if she is well built with Doug fir planking, I doubt she was originally sheathed. Dumb thing to do, as you now know.

[Patrick Miller]

Dumb thing to do? Well the builder DID quite a number of dumb things. After building the hull pretty much to the drawings he built his own notion of a coachhouse and cockpit, ignoring the original designer's excellent and well proportioned work to produce a boxy, pokey affair that positively invited the rot that I found between the coachouse and carlins.

Also, when I bought her the Dynel and epoxy was run down onto the lead ballast keel where it had let go some years earlier and water had lifted the sheathing up to about the third plank above the garboards. (He-e-e-yyy! so maybe that's the answer... Instead of boiling her I'll just let the salt water sit in between the sheathing and the planking and wait for nature to do the work.)

For those interested in the design see this link.

web page (http://www.dngoodchild.com/5375.htm)

[Patrick Miller]

IT WORKS!!

The heat gun did the trick. It took me about half an hour to expose a patch about 50cm x 50cm. It wasn't as easy as old paint, but I've already found the trick is to be patient and let the heat do the work. That is, a firm steady push with the scraper at the edge of the heated part and the scraper will start moving when the epoxy is good and ready. To much too early results in gouging the grain of the fir. Similarly, pulling on a flap (hard too resist and a bit like peeling sunburnt skin - ahh the memories of a misspent, sun-drenched youth), will result in wood coming with the cloth/epoxy.

I guess I've got a few days of disagreeable work ahead, but it's just great to see that honey-coloured timber appear from under the gunk. And my planks look in really good shape too - just a few darker spots around the rivets, but I'll analyse what that means later. Seams are in excellent condition. smile.gif smile.gif smile.gif