Best waterproof covering for ply

Hiya PVB - actually - that repair worked.. :D It's the other side that went this time!

Yeah - I'd heard of it, and I've been looking for Stok Bord suppliers locally - but it's in short supply seemingly, and only available in big sheets with stupid delivery prices...
 
Fantasie 19 said:
Hiya PVB - actually - that repair worked.. :D It's the other side that went this time!

Yeah - I'd heard of it, and I've been looking for Stok Bord suppliers locally - but it's in short supply seemingly, and only available in big sheets with stupid delivery prices...
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McVeigh Parker have it, and charge £30 inc VAT to delivery an 8'x4' sheet to Chichester. You could probably find lots of uses for the offcuts!

Or do you have a friend with a big van?
 
PaulRainbow said:
Well, that's my 40 year old boat down to Davey Jones then, all of the internal bulkheads and joinery were stuck together with polyester. Anyone want a cheap old Westerly ?
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Don't give up hope! If you need to reinforce it, you just need a welding kit and a load of old angle iron....
 
pvb said:
The photo on your blog suggests that you'll have quite a job sorting out your cockpit locker lids...

View attachment 112830

... and you've said that you don't want to have to do it again. So I'd suggest a more radical approach - replace the ply lids with recycled plastic board. It's 100% waterproof, can be worked and shaped like ply, is strong, and will last for decades. You'd need to paint it to match, but I reckon it'd be a once-and-for-all solution. If you Google for recycled plastic board 9mm you'll find some suitable products.
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Thats terminal: nothing will stay on that for long, and the rot will continue to spread through the ply whatever you do to it. If you are really determined to repair rather than replace, then remember that in 2 - 3 years time that will be just mush, and the coating you put on will provide all the strength! And if you cut it out you will have to go at least a metre back from the visible damage to get rid of all the rot spores, and find truly sound timber.
 
oldharry said:
Thats terminal: nothing will stay on that for long, and the rot will continue to spread through the ply whatever you do to it. If you are really determined to repair rather than replace, then remember that in 2 - 3 years time that will be just mush, and the coating you put on will provide all the strength! And if you cut it out you will have to go at least a metre back from the visible damage to get rid of all the rot spores, and find truly sound timber.
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If I cut a metre back from that I'd lose the whole lid.. it's only a meter by half a metre whole size .. :)
 
pvb said:
Don't give up hope! If you need to reinforce it, you just need a welding kit and a load of old angle iron....
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PaulRainbow said:
I've seen pictures of that :)
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I can do all the welding for you Paul and don't confuse my welding with that guy Brent.

All my internal structure before galvanizing

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My mast compression post and chain locker before galvanizing

36086101365_60dcd8abec_c.jpg
 
Rogershaw said:
Having had a plywood boat in the UK sheathed in glass and polyester resin that delaminated from the ply inside a year is what I based my comment on.

Th fact he boat westerly is a GRP hull its the adhesion of the bulked and joinery is your concern unlike mine which was the outside hull

Also some others have made the same comment.

Glass Sheathing New wood - Methods?
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The polyester used to stick the bulkheads to the GRP is still all stuck firmly to the ply bulkheads, even the ones in the bilges.

The question wasn't about building a ply boat and sheathing it in GRP, although there have been many boats built from wood and sheathed, with a certain amount of success. If yours fell apart in less than a year it must have been poorly designed and built.

Thanks for the link, looks like plenty of people have been successfully using polyester.
 
Rogershaw said:
I can do all the welding for you Paul and don't confuse my welding with that guy Brent.

All my internal structure before galvanizing



My mast compression post and chain locker before galvanizing
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That's very kind of you to offer Roger, but i can weld. Gas, stick, MIG, TIG (including stainless). I've got a TIG set in the van.
 
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PaulRainbow said:
The polyester used to stick the bulkheads to the GRP is still all stuck firmly to the ply bulkheads, even the ones in the bilges.

The question wasn't about building a ply boat and sheathing it in GRP, although there have been many boats built from wood and sheathed, with a certain amount of success. If yours fell apart in less than a year it must have been poorly designed and built.

Thanks for the link, looks like plenty of people have been successfully using polyester.
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yes I know you don't seem to like anything other than GRP.

The ply boat I had was a Dolphin built by Brookland's Aviation and was sheathed in glass and Polyester resin by a " Professional boat yard in Stourport who made boats from GRP

So more assumptions
 
PaulRainbow said:
That's very kind of you to offer Roger, but i can weld. Gas, stick, MIG, TIG (including stainless). I've got a TIG set in the van.
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So can I man also have a TIG set both at home and on my boat. I also have a MIG set and clearly stick. Gas I don't use anymore as MIG and TIG are much better
 
Rogershaw said:
yes I know you don't seem to like anything other than GRP.

The ply boat I had was a Dolphin built by Brookland's Aviation and was sheathed in glass and Polyester resin by a " Professional boat yard in Stourport who made boats from GRP

So more assumptions
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No assumptions, you said

"Having had a plywood boat in the UK sheathed in glass and polyester resin that delaminated from the ply inside a year is what I based my comment on. "

So, you think that's normal then ? Look at the thread you linked to earlier, it seems it's far from normal.
 
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PaulRainbow said:
No assumptions, you said

"Having had a plywood boat in the UK sheathed in glass and polyester resin that delaminated from the ply inside a year is what I based my comment on. "

So, you think that's normal then ? Look at the thread you linked to earlier, it seems it's far from normal.
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Yes the link I read as the recommendation is to use epoxy and not polyester.

A mirror dingy I renovated for my club had polyester sticking the tape on . I could could rip it off very easy I replaced all tape using epoxy.

But you make up your mind despite warnings to the contoury buy others not me.
 
Rogershaw said:
Yes the link I read as the recommendation is to use epoxy and not polyester.
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Guess you skipped over post 10, 11, 12, 14, 15, 20, 22, 24, 25, 26, particularly those by Fisherman

Boat Sheathing with Glassfibre

Of course, the OP is talking about a hatch cover, which naturally needs to be done with epoxy and 72 layers of woven glass mat, as it's going to be an essential part of the boats structural integrity.
 
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I really like SP Eposeal 300, get the sealing done in a day but I would say the biggest thing is to use decent ply.

I made sone locker lids when I first bought my boat with b&q ply (I needed something fast) which I sealed with west and they lasted a season. I have remade them in robbins elite and eposealed them this time after making other things with the same method. One offcut has been outside in our garden for 2 years with unsealed holes drilled in it with no sign of deterioration.
 
If OP or any one else wants to use epoxy on ply wood. I am not saying it is a good idea, however first layer of epoxy can be thinned with methylated spirits (alcohol.) You can also improve penetration by warming the wood (and epoxy) so that as it cools it tends to draw in the resin. Subsequent layers should be applied before epoxy really hardens.
ol'will
 
PaulRainbow said:
Guess you skipped over post 10, 11, 12, 14, 15, 20, 22, 24, 25, 26, particularly those by Fisherman

Boat Sheathing with Glassfibre

Of course, the OP is talking about a hatch cover, which naturally needs to be done with epoxy and 72 layers of woven glass mat, as it's going to be an essential part of the boats structural integrity.
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Well it you are happy to use polyester resin rather than better epoxy on you boat it it delaminated that your problem if you do that on a customers boat it becomes your customers problem.

I know which way I would do epoxy every time

Glass Sheathing New wood - Methods?

There seems to a difference of opinion as to the longevity of the quality of polyester to plywood adhesion as the above post indicates.
 
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Loads of boatbuilding has been done successfully using polyester on plywood.
The bond is not as strong as epoxy, but a competent designer or boatbuilder will understand that and design the boat such that the bond is not overloaded. With epoxy, you can use a small fillet and it will be strong. Will polyester, you need a larger area, overlapping the glass a good distance onto the plywood. If you don't believe this is a good way of building a boat, your choice of boat may be quite limited!

For a locker lid, if I were using polyester, I would cover the whole top in a couple of layers of glass and resin. Then the strength is in the glass and the ply is just stiffening the panel. An 8mm ply lid is likely flexing enough to crack the surface coating when stood on, so toughening it up with some GRP might work well.

A lot of the time, it's not just the choice of materials, but are the materials used properly?
 
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