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Old 07-07-2011, 15:56   #1
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Plywood vs GRP

I am looking at buying a boat and am familiar with and currently own a GRP boat. One of the boats I;m looking at is a plywood hull and I wanted to get people's opinions on this vs a GRP hull.

The boat is in good shape, bilge is dusty so I'm not worried about rot, more just the general reliability and strength of plywood vs grp in offshore passages.

The one thing I did notice is that the saloon floors of this boat seemed to have an unusually steep slope and that the bilge covers were very hard to remove (I was actually unable to remove one, it was stuck in so tight). Would this be a warning sign that I should be worried about?
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Old 07-07-2011, 22:22   #2
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Re: Plywood vs GRP

There certainly are some good Plywood boats...I dont know that I've seen many or any good really old plywood boats.
All things being equal I would go with Fiberglass for ease of long term maintenance.
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Old 07-07-2011, 22:44   #3
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Re: Plywood vs GRP

Get a survey. Get a survey. Get a survey. Some ply boats are good ones. I have built several and am building a 34' ply cold molded boat at this time. It will be my home for the forseeable future. Having said that, I have seen a lot of really badly done ply boats. [Actually, I guess I have seen a lot of badly done fiberglas boats as well ...]. the major difference is that fiberglas does not rot. Since you lack the expertise to see the difference, I would go with glass.
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Old 07-07-2011, 23:39   #4
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Re: Plywood vs GRP

I know the Newporter 40s were excellent boats. But with all boats, they need vigilance. I have owned steel and FG. No needto drum that debate up again other than to say, I like FG now.
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Old 08-07-2011, 05:30   #5
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Re: Plywood vs GRP

We met a plywood mono lifting keel French home build thing when sailing the Pac. So, a well executed plywood boat can sail far and out no hiccups. I have also seen a couple of plywood ocean sailing cats.

As with any material - make sure the design is sound, the build is professional and the maintenance has been adequate.

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Old 08-07-2011, 05:56   #6
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Re: Plywood vs GRP

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Originally Posted by barnakiel View Post
As with any material - make sure the design is sound, the build is professional and the maintenance has been adequate.
b.
We walked around Le Crouesty in France a couple of years ago and saw a few of these. So good is the finish you can't tell that it's made of plywood.

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Old 08-07-2011, 18:16   #7
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Re: Plywood vs GRP

My last boat was stitch and glue-- plywood and epoxy--built by Sam Devlin in the Pacific Northwest. This produces a better boat than fiberglass if done correctly: stronger, lighter and no more difficult to maintain, since the wood is encapsulated by the epoxy. There is no exposed wood.
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Old 08-07-2011, 18:30   #8
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Re: Plywood vs GRP

Although there must be some good ones out there... it is highly likely that the boat will be VERY hard to resell.... Done with first class plywood like Brunzeel and epoxy etc I suppose they will last quite a while, but just because plywood is encapsulated, doesnt mean it wont rot inside. there must be places for water to start the rot on every boat... bolt on keel? Deck hardware? etc etc... I like the concept, the Devlin boats are really cool..but there is a market resistance to most ply boats just like the cement boats...
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Old 08-07-2011, 19:10   #9
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Re: Plywood vs GRP

Even fiberglass boats have plywood somewhere on them, but the hull should be made of glass.
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Old 08-07-2011, 19:46   #10
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Re: Plywood vs GRP

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Originally Posted by Cheechako View Post
Although there must be some good ones out there... it is highly likely that the boat will be VERY hard to resell.... Done with first class plywood like Brunzeel and epoxy etc I suppose they will last quite a while, but just because plywood is encapsulated, doesnt mean it wont rot inside. there must be places for water to start the rot on every boat... bolt on keel? Deck hardware? etc etc... I like the concept, the Devlin boats are really cool..but there is a market resistance to most ply boats just like the cement boats...
I had an offer for within a few percent of asking price within 10 days after the Yachtworld ad was placed, plus a backup offer in case the first buyers backed out.(They didn't.)

There is no place in a stitch and glue boat for the rot to start, because the wood is impregnated with epoxy at all stages of construction. It's not a wood boat that is later glassed or epoxied over. The Devlin boats aren't just cool. They're bulletproof, and knowledgable buyers know it.
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Old 09-07-2011, 07:10   #11
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Re: Plywood vs GRP

As a plywood boat owner perhaps I can add a comment. My Van De Stat Dogger (31 ft) is plywood. After some 30 years in the water, I took her back to bare wood inside and out.

95% of the hull was in perfect condition as was all the cabin. About 15% of the deck required replacement but I guess I replaced maybe 30%.

I elected to epoxy coat her inside and out plus adding a layer of glass below the waterline.

I suspect she now has at last another 30 years of life, maybe much more.
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Old 09-07-2011, 08:57   #12
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Re: Plywood vs GRP

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Originally Posted by Curmudgeon View Post
... There is no place in a stitch and glue boat for the rot to start, because the wood is impregnated with epoxy at all stages of construction. It's not a wood boat that is later glassed or epoxied over ...
Not according to Sam.
Excerpted from Devlin’s website
Devlin Designing Boat Builders
“... the boat is much easier to maintain, mostly because the structure is so very strong and all the surfaces are carefully and completely sealed with the same epoxy resin that was used to bond all the parts together thus keeping moisture and water from migrating into the dry wood. If you keep the wood dry then paints and finishes aren't prone to cracking and peeling off and the wood in the structure is mummified from the possibility of rot, which requires considerable moisture in order to flourish ...”
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Old 09-07-2011, 10:15   #13
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Re: Plywood vs GRP

If you're in the PNW heres a ply 30 footer with perkins diesel for $7400...probably means you can get her for $5k! (no affiliation)
Moving - Must Sell - 30' Sailboat

Not sure what you mean by sloped floors...? the bilge covers are likely swelled up from moisture. The happens withgrp or other boats too... although may be worse with just a ply board...?
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Old 09-07-2011, 23:11   #14
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Re: Plywood vs GRP

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Originally Posted by GordMay View Post
Not according to Sam.
Excerpted from Devlin’s website
Devlin Designing Boat Builders
“... the boat is much easier to maintain, mostly because the structure is so very strong and all the surfaces are carefully and completely sealed with the same epoxy resin that was used to bond all the parts together thus keeping moisture and water from migrating into the dry wood. If you keep the wood dry then paints and finishes aren't prone to cracking and peeling off and the wood in the structure is mummified from the possibility of rot, which requires considerable moisture in order to flourish ...”
Gord,

Can you explain your point more fully? I am assuming you see a difference between "surfaces are sealed" & "wood is impregnated".

While those statements are not the same thing, they explain (to a degree) the way plywood boats are sometimes protected and while neither totally explain the process, they do, in lay terms, describe the concept.

Or perhaps I have completely missed your point!
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Old 10-07-2011, 05:12   #15
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Re: Plywood vs GRP

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... I am assuming you see a difference between "surfaces are sealed" & "wood is impregnated" ...
Absolutely!

Impregnated:
To fill or penetrate throughout; saturate, permeate.
In which case the epoxy would be absorbed into the wood, which would be saturated or infused with epoxy, like a sponge with water.

Sealed:
To encapsulate, enclose.
In which case the wood is merely coated (painted) with epoxy, and any mechanical fastening in (through) the wood must penetrate the protective coating.
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