New cabin sole anarchy

Grizz

Beats the crap out of me
442
165
Northport, NY
So- the 3/4" teak and holly veneer plywood that makes up the cabin sole in my Frers 33 has delaminated to the point of no return. I now own a new 4x8 sheet of the same material, purchased for an eye-watering $500 for a single sheet! I will certainly endeavor to measure a bunch of times and cut once- I was able to remove the old one intact to serve as a template.

What's the current wisdom on a finish? The underside is often directly exposed to water in the various shallow bilge compartments, so I am assuming an epoxy coat below and on any edge plies is a given. I have had a few thoughts for the exposed side- varnish over epoxy, with the first epoxy coat thinned? Straight varnish without epoxy? 

Any and all suggestions would be greatly appreciated!

 

phill_nz

Super Anarchist
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start with any epoxy resin thinned 10-20% ..  cup test the ratio for gel and cure before using on the ply

use epoxy thinners only

keep feeding it till it gels .. it soaks up quite a bit

 
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Zonker

Super Anarchist
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Minimum 2 coats on the underside and 3 on exposed edges of cutouts (due to wear and tear).

See this thread and my recommendation for the top surface




 

Ishmael

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49,399
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Fuctifino
Make the fit quite loose, otherwise the buildup of finish can make everything slightly too large and having to sand it back and start over is a pain in the ass.

 

Grizz

Beats the crap out of me
442
165
Northport, NY
Undercut (bevel) them slightly - then they can fit snug but release easily without wearing the finish off the edges.
Thanks Sloop-actually, the edges have changing bevels, and the forward section tapers in thickness from the center down to about 1/4” at the edges, but maintains the entire 3/4” thickness for the rear two thirds. Like a freakin’ violin soundboard, in case I was worried about it being too easy!

 

Grizz

Beats the crap out of me
442
165
Northport, NY
Make the fit quite loose, otherwise the buildup of finish can make everything slightly too large and having to sand it back and start over is a pain in the ass.
Thanks Ish- it also just barely makes it through the companionway, and the winter cover is on so test fits are going to be a pain in the ass!

 

Grizz

Beats the crap out of me
442
165
Northport, NY
Minimum 2 coats on the underside and 3 on exposed edges of cutouts (due to wear and tear).

See this thread and my recommendation for the top surface
Thanks Zonker- I’m not planning to go with any non-skid strips. The old one was finished with gloss varnish, and as a couple of folks have mentioned I’ve never found it to be an issue. I looked through the thread and didn’t notice whether you suggested an epoxy first coat, or just straight varnish for the top surface.

 

Grizz

Beats the crap out of me
442
165
Northport, NY
start with any epoxy resin thinned 10-20% ..  cup test the ratio for gel and cure before using on the ply

use epoxy thinners only

keep feeding it till it gels .. it soaks up quite a bit
Thanks Phill- that accords with some of the suggestions I’ve heard.

 

Grizz

Beats the crap out of me
442
165
Northport, NY
Fleetwood said:
I use Synteko here in Oz. Its a part of Akzo Nobel so probably widely available in the US. (Their oil on the top, epoxy painted (Interprotect 2K) underneath and sides.)
Thanks Fleetwood- do you apply the Interprotect over bare plywood? Also which Synteko product do you use? Is it two-part acid curing?

 
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Grizz

Beats the crap out of me
442
165
Northport, NY
Don't epoxy the boards in a damp environment. The humidity gets into the wood and causes hazing in the finish when it outgasses afterwards.  Make sure the ply is kept DRY. 
Thanks PaulK- the PO had the sole refinished before i bought it, and the coating failed extensively because of moisture intrusion. I’ll be doing the work in my basement over the Winter, so moisture shouldn’t be an issue,

 

Zonker

Super Anarchist
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Canada
Varnish a scrap piece of cheaper but smooth plywood about 2' square. Prop it up in the living room so it's about a 30 degree angle. Spill a glass of water on it. Stand on it and report back. :)

 

DDW

Super Anarchist
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985
Make the fit quite loose, otherwise the buildup of finish can make everything slightly too large and having to sand it back and start over is a pain in the ass.
It isn't just the finish. You start with dry plywood in your workshop and end up with moist plywood on the boat, it gets bigger even without the finish. This is why you leave flooring inside the house its going in for 8 weeks before you install - to let it settle at the ambient moisture content. 

 
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When epoxy is thinned, it’s more permeable when cured. When the solvent goes away, the resultant solid is porous. THis defeats the purpose of sealing the plywood. 
There’s more on this at Westsystem.com or maybe Epoxyworks. They tested the moisture uptake of epoxy coated samples in wet conditions. 
The other way to get epoxy to be thin is heat. Apply in warm conditions. Warm the plywood, not the epoxies. 
 

 

sculpin

Super Anarchist
Oversize drill the screw holes and epoxy fill them, otherwise water will get in that way and you will have a wet ring around each screw.  On my second go at this I drilled the screw holes way oversize and fit solid teak plugs in them (epoxied in place), then flipped the sole upside down and filled the remaining cavity with epoxy.  Re-drilled the proper size for the screw through this.

 

slug zitski

Super Anarchist
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799
worldwide
So- the 3/4" teak and holly veneer plywood that makes up the cabin sole in my Frers 33 has delaminated to the point of no return. I now own a new 4x8 sheet of the same material, purchased for an eye-watering $500 for a single sheet! I will certainly endeavor to measure a bunch of times and cut once- I was able to remove the old one intact to serve as a template.

What's the current wisdom on a finish? The underside is often directly exposed to water in the various shallow bilge compartments, so I am assuming an epoxy coat below and on any edge plies is a given. I have had a few thoughts for the exposed side- varnish over epoxy, with the first epoxy coat thinned? Straight varnish without epoxy? 

Any and all suggestions would be greatly appreciated!
When the floor boards chafe against floor timber’s the paint film breaks and you get water intrusion 

to prevent the flooorboards from touching the frames many boatbuilder use rubber stand offs 

these are rubber cord, o ring material about 10 or 12mm in diameter 

a hole is bored into the bottom perimeter at floor timber contact and a short piece of rubber is inserted 

the is done around the perimeter at perhaps 8 inch intervals 

once the rubber cord is inserted and glued it’s trimmed back with a razor blade so only a few mm is standing proud and full floor timber contact is achieved 

on some installations these rubber bumpers are used on the floorboard edges to prevent contact chafe 

always heavily radius the bottom edge of the floorboard to prevent edge damage 

these rubber bumpers also prevent squeak  and vibration 

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