Jon boat: Adding plywood decking. How to seal

joulian

Cadet
Joined
Mar 6, 2010
Messages
16
Hey guys , I am working on adding a front deck and back deck to a 16' jon boat ( its a little over 4 ' wide at top). How do I need to seal the wood. It is marine grade plywood. I have heard you are suppose to seal it off where you cut the new pieces. What do you seal it off with?
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Re: Jon boat: Adding plywood decking. How to seal

Spar varnish works well, several light coats.

NOT polyurethane !!

Or use an epoxy resin.

You must seal the entire piece, not just the edges.
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,019
Re: Jon boat: Adding plywood decking. How to seal

why not polyurethane?

Because it will not survive the marine environment and spar varnish will since the spar has uv inhibitors.
 

kfa4303

Banned
Joined
Sep 17, 2010
Messages
6,094
Re: Jon boat: Adding plywood decking. How to seal

+1. You can even get spar varnish at lowes/HD, but you usually have to order epoxy. I'd say a few coats of Spar varnish followed by a top coat paint of your choice. Although, lots of folks just leave the wood unpainted after using the varnish. However, if you do paint Rustoleum oil based enamel is an oldie but goodie and holds up well on the water and you can get it just about anywhere. It takes a while to fully cure and can be a bit slick when dry, but it works great. I did several coats on 2 decks and 2 benches with less than a qt. Pay special attention to the cut edges and pick up some 3M 5200 (also at lowes/HD) to dip all of the hardware you may be using in prior to installation. (btw only use Stainless steel or aluminum pop rivets in a boat.)
 

jigngrub

Fleet Admiral
Joined
Mar 19, 2011
Messages
8,155
Re: Jon boat: Adding plywood decking. How to seal

For those that don't know, there is an exterior grade of Spar urethane that has the UV inhibitors. It's the Minwax brand.

http://www.google.com/products/cata...RIreT8v0GoKQ8wS03PiDCw&sqi=2&ved=0CIwBEPICMAU

I'm not really sure that UV inhibitors are that important if the decking is going to be covered with carpet or something else.

Epoxy resin is the best sealer, but it doesn't have UV inhibitors so it needs to be covered.
 
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