wooden runabout deck seam alternatives, solutions

[Oyster]

I have tried numerous alternatives over the years with pretty good success, but this time around the use and storage of the boat will be entirely different. This application will be stored outdoors under a vented cover during the bulk of the summer heat, so several methods such as tinted epoxy may not be the absolute ideal setup. I am truely leaning towards the wood filled seams.

I have used the cedars and even the cypress in the wider boards, which has worked out pretty well. But with the planks being all mahogany, using either wood in smaller widths will probably not be the ideal solution here, IMO.

So please show me your decks and maybe explain some detailed setups. If you know or have any buddies that has some time of their wooden runabouts with simular designs, please step up and type a few words of wisdom for me.
You can even add your thoughts on the caulks if you have some time on the setup too. But it must hold varnish and i have never liked the cupped sections which puddles the finishes, which seems to always take place with flexible stuff.

TIA

[gonzo]

Deck seams on a planked deck should be caulked with a flexible compound. Epoxy is not a good option. The decks that have two tone wood look great, but don't take weathering well.

[Oyster]

Originally Posted by gonzo

Deck seams on a planked deck should be caulked with a flexible compound. Epoxy is not a good option. The decks that have two tone wood look great, but don't take weathering well.

Actually a common and a successfull method is and has been tinted and thickened epoxy for show piece boats and boats that primarily reside on a trailer in a protected area. Most of the decks are also laminated to plywood with epoxy glues, which leaves the entire component a cold mould style layup. The variance here is that it will be clearcoated instead of primed and painted. We know that this method is used in the building of hulls. We also know that even while the decks are somewhat protected, some UV does penetrate through the canvas covers and along with it some heat intensity.

My only issue is both the increased area of dark mahogany, which the planks will be with the narrower required strips in semi tropical conditions and the sun beating down even on a semi tarped decking. We are probably dealing with the worse of the worse, not because of the UV as much but the added heat buildup and the night cool down.

[gonzo]

Showboats are different in that they don't get weathered like boats in normal use do. Mahogany swells and shrinks less than some of the softer woods like pine or cedar. The heat will dry the wood and make it move. Are you laying thin planks over plywood or is this a planked deck over beams?

[PAR]

Two part polysulfide Mike. It's the only way to go. The holly, teak or mahogany decks can't take the moisture gain/lose cycling. It'll spit out the the little strips pretty quickly in your summer heat.

Is this a veneered deck or will they be hard fastened? A hard fastened deck tolerates this treatment better then glued. I have seen some thick veneer decks (1/4") that have been bedded in polyurethane, which also served as the fastener. This also had polysulfide seams. These seemed to hold up well. They used a heavy fabric sheathing on the subdeck (plywood and at least 16 ounces of fabric), then a notched trowel of polyurethane for the bedding/adhesive. In some cases I've seen them screwed from below, but the vast majority are just stuck in goo. Tape the seams and apply the seam compound. Sand when cured.

[John Riddle]

My experience is that a thin mahogany veneer on the surface (usually about 1/8") laid in epoxy over plywood with a plank width of about 1-7/8" and an 1/8" seam filled with epoxy has proven reliably stable in Ohio. I've done several that way without issues.

The CC Riviera pictured is dry stored on a trailer on a blacktop parking lot all summer with a tented, tan, full-length cover. We built it in 1991 and have refreshed the deck finish just twice (not refinished but recoated) mostly due to the repair of inevitable nicks and dings.

Wider planking or thicker planking has more tendency to shrink and swell enough to split grain along the seams. In that case, a different approach is probably required.