Wood-Fiberglass Transition

I currently have a fiberglass deck on my boat; however, I am redoing all of my wooden side rails, rod holders, dashboard, cuddy door, etc- replacing with all new wood. I have decided that it would look really sharp to go ahead and put in a matching wood deck.
The question I have for somebody is this: where my wood deck butts up to the gunwale (which are still fiberglass) there is a considerable gap due to the slope of the wall there. I see this area becoming filled with blood, grime, and slime before long, and in so becoming quite unsightly. Will it adversely affect my wood decking (sealed with spar varnish) to pour a clear fiberglass resin into that gap where the gunwale and floor meet and so seal it off from coagulate?...

Any help is much appreciated!!!

 

I've done this type of treatment on several 'glass boats and you have two major issues to contend with. Firstly is keeping the veneer attached, particularly if it's teak and second are these transitions areas.

The places where wood will butt against a toe rail, cabin side etc. will be substantially radiused, which makes a problem. You could just fill these areas, but it looks terrible with a pool of resin around the perimeter. The best solution is a covering board which raises up around the perimeter and covers this transition from wood to 'glass. These are glued in place just like the rest of the decking, but are back cut to allow them to sit square on the irregular surfaces of these areas.

The biggest problem, especially in southern states where sun light is more direct, is perfect adhesion of the veneers. I just did a teak and mahogany deck on a plywood boat and after a week of hot Florida summer sun, it had four small blisters. These weren't totally unexpected, though it would have been nice if I'd gotten lucky.

When you apply the deck, you have to insure complete and perfect glue contact between the two materials. I used a notched trowel and was careful, but four 1" to 2" long blisters appeared anyway. In direct sun, these were areas where a small air gap was present, which heated in the sun, expanding into a blister. I slit open each, injected adhesive and weighted it down until cure. This doesn't happen on thicker stock, just veneers.

So, can you do it, yep, you sure can. Do you want to maintain this type of deck, probably not if it's veneer, but maybe if solid lumber (3/8" minimum). You'll need to mill up some custom covering boards for the transition areas, which is tedious, but worth it if you just have to have the look. The other option is as you suggested and back filling these areas with resin to level it flush with the wooden decking, but it will look like amateur hour and will also need UV protection (paint, varnish, etc.).

 

What I plan on doing is attaching a half inch grid of pressure treated lumber to the fiberglass bottom using Epoxy-Tie Adhesive and VGC Adhesive Anchors to go into the foam core. Then I plan on using 1/2"x1 3/4"x6' teak planks to lay the deck, attached to the below flooring system with the same Epoxy-Tie and brass, ring shank nails (the brass being for an even more decorative look). Essentially raising the entire deck an inch...

So what you're saying is around the edges, where the gap forms I just need to take the time of sanding and shaping a toe kick to the contour of the gunwales and cabin side, rather than trying to fill the crack? Sounds extremely tedious, though I would rather do it right and have it look better.

Thanks for the help; oh, and what do you think of my idea for the decking system I just talked about? Does it all seem sound and stable?

 

Epoxy and pressure treated lumber don't mix. The glass tube anchors (Vinylester Glass Capsule) you mention will not work very well with the core. The best result will be epoxy bonded (not glued, bonded) fasteners to the core. You also want bronze not brass ring shanks, though these wouldn't be the best choice either.

Look, attaching a decking system to a cored deck requires some thought and serious understanding of the materials and loads involved.

You're making this a lot hard then you need. One of the problems is fastening to the cored deck. Don't bother, bond directly to the 'glass, thus skipping the trouble of fastening to the core. I'd seriously rough up the deck, with say 24 grit, then epoxy coat the exposed mat with at least three neat coats. Now you have a base that can be bonded to the decking.

The decking could be set into epoxy if it's not teak. If it's teak, then you might consider 3M 5200 with 3M 101 in the seams after you're bonded. I've had some luck prepping teak and other oily woods for epoxy bonding, but it requires careful prep. Of course both these bonded decks will be destroyed if repairs required removal.

This isn't the way I recommend a wooden deck be attached to 'glass yachts, but it could work.

The only way I recommend this be done and can offer reliable results, is to lay down an encapsulated plywood substrate, which is then 'glassed over, to which the new wooden deck is both mechanically and chemically attached.