I’m replacing a deck on an 1895 Bailey Bros 2.5 rater. I’ve laid 9mm marine grade ply as the first layer, primed with thinned metalex with red lead over the top. I have some 13 mm nz kauri (ex floorboards with grooved bottom) which I want to lay over the top. I don’t want to put any glass on, as I’ve only ever seen it cause rot in this situation, whereas where I’ve seen ply as a substrate treated only with lead paint, it’s been fine more than 50 years later.
So my question is, how best to bed and caulk the top layer of planking? I can use copper and bronze to fasten it, but would like to have it pretty stiff at the same time. I’ve replaced a couple of deck beams aft of the cockpit, and attached tie rods at an angle through them to bind them to the stringers, but some of the side deck beams are pretty flimsy looking and want to maintain a bit of stiffness. I’ll probably retrofit some tie rods there.
Anyway, have been thinking of using a modern bitumous roofing goop as bedding, caulked with a modern compound, planking nailed and in some places riveted down. Any thoughts? I think gluing it down might make the timber lift with changing temp and humidity.
Hi Gavin,I would recommend using Sika 221.It is used in the automotive industry for general bonding and sealing.Comes in sausage or cartridge form and in black.Sticks very well to timber.I was told by a Sika rep that it does the same job as Sika 291,298 (marine industry)but at a cheaper price.You can use it to caulk between the decking edges but it does leave minute pin holes (from small air bubbles) when sanded.The Sika 290 DC Pro is better for this.
I would screw( a stronger and more rigid fastening)rather than nail the planks,nails could work their way out over time especially with a permanently pliable bedding adhesive such as the 221.Depending on the scantlings of the yacht, flexing could be an issue.
Hope this has been of some help.
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