Dynal

[gregJ]

Ive just turned over my Green island 18 and am thinking of dynal sheathing it below the waterline. A local boatbuilder has told me that dynal has a tendency to peel off after a while. Has anyone else experienced this?

[Figment]

Any sheathing can have a tendency to delaminate if applied improperly. The cloth isn't the issue.

The issue is the wood's ability to wick moisture through the back (unsheathed/unsealed) side, and the consequent expansion and contraction that comes with cycles of wet and dry. Search around this forum and you'll find more on this topic than I could type in a day's time.

[Dennis Marshall]

I used xynole on the bottom of my Dobler 16, a fabric that is similar to dynel. 4 years and much hard use and groundings later, I am having no delamination problems at all.

Dennis

[Keith Wilson]

I have never heard even rumors of properly applied Dynel/epoxy delaminating. The one boat I did it on is still fine after seven years or so. I would guess that it would stay on even better than fiberglass/epoxy because it's stretchier, but my experience is, of course, limited.

[Buddy]

Have to agree I would suspect problem is in the application. My Dynel's righty tighty after four years. I do feelits important to wet out your plywood with straight resin and let it absorb that and let it get tacky ( oo completely cure and then clear off the blush) before you put on the fabric.
I know a lot of people position the fabric dry on bare wood and then let the resin soak thru. I suspect sometimes the unsealed wood wicks away too much resin at the interface of the bond.Maybe not often a problem but you do hear the occasional bad luck story.

[Doug Wood]

My deck and cabin top is covered with Dynel and has remained in perfect condition for 15 years.

[Christopher Locke]

Greg, I'm building a Green Island 18 as well but am not as far along as you are. I've sent you an e-mail; love to exchange notes as we each move forward.

[Frank Wentzel]

Greg

You might check on the resin used in the lamination the boatbuilder spoke of. A very large percentage of people I have spoken to seem unaware that polyester resin is often the culprit in delaminations. I know some have used polyester with good results but the percentages overwhelmingly favor epoxy.

/// Frank ///

[gregJ]

Thanks for all the info. I am a first time builder and needed a bit of reassurance. I think I will proceed with the dynal as planned I have heard good things about its abrasion and impact resistance and I run aground a lot.

[Ex-Oceangoddess]

I think the important thing is to have the plywood VERY clean, i.e. no contaminants at all, rough up the surface and keep note of the necessary temperature constraints. I have experienced what happens when someone (not me, thank the gods) didn't realize that drops of oil etc. will make it impossible for dynel and epoxy to get married properly to the substrate.