Seal or Don't Seal Marine Grade Plywood Decking?

[dls322]

Hi Everyone.

I just finished re-decking my project pontoon. After finding out my deck was not as good as i previously thought, i figured it was better to just replace it instead of putting nice carpet over junk wood. i will add some pics.

My question is should I be adding some kind of sealant to the wood? The deck is Marine Grade 3/4 plywood that is not pressure treated (because of the reaction to aluminum). I sealed all the bolt holes with caulk and sealed between the sheet gaps and i also rubbed some caulk around the edges of the wood. I also laid down rubber weather stripping on all the cross members that the wood will rest on. I did not "seal" the wood though. I have read many posts on people saying that:

-Marine plywood should be left unsealed and that it's fine how it is...
-Other people say if you seal it you are trapping in water and it will rot..
-And then other people say you should seal it to make it last longer....

I'm kinda confused here....
I already put the carpet down so the top deck is how it is, but should i apply a sealant to the underside of the decking??

I'd like to do the project correctly and get 8 years out of the deck if possible. I leave the boat in the water at our dock for the summer 4 months, but when it's not in use will have it's cover on, and in the winter it's fully covered up and sheltered.

Seal the bottom or don't seal the bottom....the million dollar question! lol

Thanks

 

[dls322]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

No opinions? Disappointing....

I guess i will leave it unsealed....rather not commit myself to something that might be wrong. Plus i gigure if they are not sealed from the manufacture then it must work for them.

 

[ezmobee]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

I could move this to resto for some better responses if you'd like. My instinct would be to seal it but I just don't know how correct the idea of "sealing it traps in moisture" line of thinking it. I can't immediately discredit it.

Where do you dock it? I live in Mount Wolf and boat at Goldsboro, Clarke, Conowingo, and occasionally the bay and Raystown.

 

[fishrdan]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

-Marine plywood should be left unsealed and that it's fine how it is...
-Other people say if you seal it you are trapping in water and it will rot..
-And then other people say you should seal it to make it last longer....

- Untreated marine plywood will rot just as quick as other untreated plywood since it's built from the same wood. (comparing doug fir to doug fir, not all marine ply is from doug fir)
- I agree that, trapping water inside encapsulated plywood will rot it out just as if it were unsealed ply that can dry out, (possibly quicker).
- If sealed plywood has all the penetrations (bolts/screws/staples) sealed it will last for a long time. (IF all the penetrations are sealed)

There are many types of marine plywood though. Pontoon decking is a marine plywood that's CCA treated and aluminum safe, it's not the green ACQ treated stuff from Home Depot that will eat your boat.

I don't have any advice for what to do since everything is all ready bolted on the toon, too late to bathe the individual panels in treating solution and too late to fiberglass each panel

 

[dls322]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

Where do you dock it? I live in Mount Wolf and boat at Goldsboro, Clarke, Conowingo, and occasionally the bay and Raystown.

Hi, i live in northern York, off the emigsville exit off 83. We have a place on Lake Wallenpaupack in the Poconos, so once she is done i wil be bringing her up there to live. Shoot me a PM, it would be nice to talk to someone about the boating around here.

 

[dls322]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

I think i'm going to let it go ...$500 wood investment, plus carpet, plus glue...but i figure ifi get 6 years out of it i will be happy, then can replace the carpet again to something new and repeat..or upgrade to an aluminum deck. It would be MUCH easier if everyone had an overall consensus to what is the best direction for everyone to go by when they redeck, because my research shows that it's 50/50 between treat or not to treat.

 

[ezmobee]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

The BEST direction is probably to spring for that really expensive decking from somewhere like pontoonstuff that is treated but with non-corrosive chemicals.

 

[fishrdan]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

I guess you could treat it a borate treatment. I used untreated dour fir marine ply on my rebuilt and did the borate treatment, along with soaking each panel in Termin-8. There are borate treatments available, but it's just a surface treatment, that can wash away, probably the best thing for the underside of a toon... I did a homebrew borate treatment, borax laundry stuff boiled up in water to dissolve it, then applied. It gives the wood a gritty feeling that I didn't like, like nails on the chalkboard. Of course, these are just a surface treatment and you'll be lucky to get penetration down deep. (I cut open a piece of treated ply to see how it worked, the Jacso soaked stuff only went in 2-3 ply's deep with the center plys untreated...)

that really expensive decking from somewhere like pontoonstuff

They do offer a 10% discount if your order is over $2000 :facepalm:

 

[arntarchie]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

just finished mine. 2 coats of epoxy paint end at every bolt and screw penetration I used a large bore 16 ga. vet syringe fore livestock and injected paint into the hole fore larger holes I put tape on the underside and let the wood sock up the paint. time will tell

 

[Paddy60]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

I did something completely different. Years past I used standard treated 3/4" plywood. It did not rot but with in one year was delaminating. So second time around I bought 3/4" b/c plywood. Seal coated all sides/edges and drilled holes with a left over clear coat. It was about 3-4 coast so really sealed. Then, I used a elastomeric roof coating, sveral coats with last coat having non slip sand in it.

Most important, I left off the carpet. I do have a rug or too. The wet carpet is what kills the deck, it can't dry out quickly. At a glance I can see all my deck is in good shape. When a spot needs tending, I will see it and brush a bit more on. I leave my 'toon in our slip and never cover it. We live on a lake so I don't want to cover and uncover every day.

I know this is an experiment and time will tell. But the cost was very low, 5 sheets of c/b ply, 5 gal elastomeric roof coating. At one year never covered looks good as new.

Patrick T

 

[dls322]

Re: Seal or Don't Seal Marine Grade Plywood Decking?

LOL, Seems like everyone has their own custom solution...I hope they all work!

Do the pontoon manufactures treat the wood they used when they originally built the boats?

I think next toon i buy i will look for one with an aluminum floor.

I was on a tour yesterday for work that was at a truck body manufacturing facility...I was jealous of all the aluminum they had. I guess next build you look into salvaging a truck body for the aluminum for a floor or i also was thinking about using old highway signs, those things are huge when you get close to them, but imagine they recycle them when they are replaced.

Oh well...hopefully i will get quite a few years out of my setup