can you Re-laminate De-laminated 1/8" decking to new plywood?

[jackrabbit66]

97 Seasport 19' dual console


Background:

I bought my boat a few years ago knowing it had some soft spots in the deck. It turns out that the deck is made of 3/4" OSB instead of plywood. The rest of the boat seems to be well made and the stringers are all in good shape, from what i can see. under the OSB is a 1/32" layer of glass and resin however the deck is a 1/8" fiberglass shell like the hull and frame of the boat. The OSB is pretty much a water logged sponge at this point & can be scraped off the fiberglass & deck with a spoon in some spots & in others i can remove the OSB with an oscillating saw.

Theory: I would like to lay in new marine grade plywood, saturated with resin, fiberglassed seams & edges. once the plywood is in place I would use some kind of adhesive to "glue" the old 1/8" fiberglass shell to the new plywood deck.

Reason: The fiberglass shell is 1/8" thick which provides a protective barrier from water & other damage & it just looks good.

Possible flaws to plan: I'm worried that unless the fiberglass shell is completely "laminated to the plywood deck that water is going to find its way in and cause problems.

Question: If i can remove the 1/8" deck from the osb.... CAN I RE-USE the 1/8" molded Fiberglass decking over new plywood?

Thanks!

 

[DeepBlue2010]

Post some picture so we can see what you see. I am guessing you have a deck that is part of the cap itself and the OSB was just used as a core for the deck. This is different configuration that laying a deck on top of the stringer and bulkheads and glass over it. But, instead of playing the guessing game, just let's see what are you dealing with

 

[ondarvr]

It can be done, but like already mentioned, pics help a great deal.

 

[fhhuber]

Kind of done every time someone replaces a transom in a fiberglass boat...
The new wood is glued to the old fiberglass.

So, yes it can be done.

The issue is getting a proper bond and then sealing the edges of the recovered fiberglass decking to the rest of the boat. Several approaches might be considered depending on how large of a "slab" of fiberglass and any curvature/shape to the part.

Flat fiberglass to flat wood is of course easiest. That would just be a good slow cure epoxy and lots of weights to bond the fiberglass to the wood. Then you do the edge joint work.
(several hundred pounds of sandbags may be involved)

 

[jackrabbit66]

No Title

Yes I believe you are right about the deck being a cap & the OSB being the core. The only area I have access to the OSB is inside the hatches. I have not removed the fiberglass decking yet. Once i removed the OSB from inside the hatch compartments (behind consoles),The 1/32" bottom layer of fiberglass was still in tact. I removed a section of that to reveal that the fiberglass / OSB flooring was mostly sitting atop foam & not attached to any stringers.

So if this is my configuration how to i attach new plywood?

 

[fhhuber]

The question becomes:

Are you better off splitting the deck from the hull and doing all the wood at once?

Advantage: no seams to seal up from cutting up the upper shell.

Disadvantage: lifting the upper half can be a pain. and sometimes they got the seam between the two glued pretty good.

 

[DeepBlue2010]

The solution is to get all the wet core out and re-core and yes, you for sure can use the old skin and put it back on top provided that you will prep it right.. Theoretically, You can have access to the area from the bottom (de-cap the whole boat) or from the top by cutting the top skin around the edges). Practically, you need to consider how will you be able to physically work from the top. The bottom skin is very thin (1/32 as you said) so it will not hold your weight while you are prying wet wood and move on the deck from one section to the other. it will also not hold the new core and your weight during the process plus the extra weight on top of the old skin - for clamping effect - after you are done. Something to consider when you develop your work plan.

I know you don't want to de-cap the boat. I would not either if I were you but the way it looks to me is that while it is a good amount of work, it is practically more doable.

If you are so determined not to de-cap the boat, you can build a platform to carry your weight while you are working that is not resting on the deck. I am still not sure if the thin skin in the bottom will take the weight of the new ply and the clamping weight though

 

[jackrabbit66]

if the last core was OSB then what does the new core need to be? can i just use pressure treated CDX?

 

[ondarvr]

OSB is junk, use exterior grade plywood or upgrade to foam, foam is pricy and hard to find compared to plywood though.

 

[DeepBlue2010]

No OSB or pressure treated. As Ondarvr mentioned, use exterior grade ply at the very least. I would use Marine grade but you don't have to. Of course the wood need to be prepared before you put it in but we will cross this bridge when we reach it. Let us know which way you decided to go.

 

[jackrabbit66]

ok, so if i get marine grade plywood can i just saturate it with epoxy or what do i need to do to seal it?

 

[DeepBlue2010]

First you need to decide how will you get to the core as discussed above and which resin you will be using. They are related thought becuase if you are cutting from the top and you want to glue the skin back and try to restore the finish to a cosmetically good looking state, you will not be able to use gelcoat as a finish if you use epoxy resin. Poly (Gelcoat is nothing but pigmented polyester resin) over epoxy has some compatibility issues. Epoxy over poly is OK..

Poly resin will do the job just fine. you mentioned Epoxy and that is why I brought it up.

In general, and just to give you a simplistic overview of the process omitting a lot of details, you will

• Cut to get to the core
• Pry out the core "somehow"
• Grind the layer of fiberglass that that will show after you take out the core
• Grind the skin you removed from the non-finished side and the edges (12 inch or so deep into the piece) IF you are planning to glue it back and reuse it
• pre-soak the new ply wood with the same resin you will be using to glass you work
• spread a layer if "glue" (this can be thickened resin - epoxy or poly - or other type of glue the name of which can be determined based on the resin you will be using to avoid any compatibility issues
• put the new wood in
• Glue the skin (if you cut the top) and glass the edges. Grind, sand, fair and finish
• Or fiber glass from the bottom side and call it good and install the cap.

As you see, some future steps depends on what choices were made in the previous step.

 

[Woodonglass]

What kind of boat is this? What Year is it? What area of the boat is this repair needing to be done? Can you provide pics with a better perspective so we can see where you're working?

 

[DeepBlue2010]

What kind of boat is this? What Year is it? What area of the boat is this repair needing to be done? Can you provide pics with a better perspective so we can see where you're working?

Just read the thread!! In post # 1 he mentioned the boat type first line

"97 Seasport 19' dual console"

Post number 5 has the pictures.

 

[Woodonglass]

DB2010 PM SENT!!!

I still think pics from a different perspective showing exactly where the repair is being done would be helpful. The 2 pics posted don't really show much of what is specifically being done. At least not for me. But maybe it's JUST me!!! DB 2010 may have all the info he needs to do the entire job!!!

 

[DeepBlue2010]

PM REPLIED.

Again, read the post carefully, the original poster obviously wanted the lay of the land to get a rough idea what he is up against. My reply highlighted the fact that this is an overall, over simplified overview that omits lots of details.

 

[jbcurt00]

Wood and Deep, PM sent.

Thanks

 

[jackrabbit66]

I've removed the 1/8" deck shell from the core and found completely saturated 1/2" OSB. I've scraped it all out and now I'm deciding whether to use epoxy or polyester resin.

the delima:

I will be gel coating the 1/8" deck cut out seam around the perimeter of the deck so it would seem that polyester would be best for that.

questions: will polyester resin cure under the plywood? If the new plywood is wet out with thinned down Polyester resin, will it be waterproof and cure?

 

[ondarvr]

You do NOT want to thin the resin, and either will work, there will be no noticable differences between the two resin in this application.