What is the best marine plywood

[bealsomonauk]

Why are people so devoted to okoume? It has low rot resistance, so it seems like it would not be ideal for boat work.

[2850 Bounty]

I am new to your forum but not necessarily new to marine work.

For me, the concern would be how well the particular material choice (wood) holds up to moisture issues.
Oak, for example, would be a very poor choice .....(not that this is even available in a Marine grade....I don't know)....... as it deteriorates relatively fast when in a moist environment.
Birch may be a poor choice, as it too deteriorates quickly in a moist environment when unprotected.
Any soft woods may be a poor choice with exception to Cedar or Redwood... but the strength is not there!

Fir is a great choice due to how well it holds up to moisture and it's strength, IMO. Not a perfect choice, but it offers both fairly well.
Teak, although very expensive, would be an excellent choice... but don't we have bonding issues with the more "oily" Teak?
As with any of THESE, watch what the core material would made be from. It may not be same as the surface materials.

So, while the encapsulation, via your matting/cloth and resin work, is where much additional strength lies, I think it would behoove one to consider the inherent strength alone vs a wood that may not hold up as well (regarding moisture deterioration issues).

For a bulkhead in a steel hull boat, strength may not be your extreme concern..... I don't know.


Some of you certainly know more about this than I do.
My experience is fairly limited to transom core replacements where the "Box Beam" effect (glass/core wood/glass/core wood/glass) is where the strength lies...... and is where Fir seems to be a very good choice.

Just my thoughts on that.

[rugludallur]

I just wanted to thank everyone that commented, it's great to get opinions from people around the world with proper experience.

Mostly the locally available ply in Iceland is birch, fir and pine.
I would not consider using no-name locally supplied ply because I have seen enough of it rot and encountered voids while working with it.

I still have not found any marine certified Scandinavian ply and it seems BS1088 is not commonly used or known in stores.
The birch plywood here is mostly better quality than the fir or pine but then the glues are almost exclusively water based and it's quite susceptible to rot.

Does anyone here have experience with using birch ply in a marine environment?
Does anyone know of a standard or certificate by which marine grade birch ply can be sourced?

Jarl
www.dallur.com

[Ilan Voyager]

You won't find marine certified plywood in "ordinary" plywood resellers. The market is very small. First ask shipyards, even steel shipyards use plywood. Second, ask the importers: if the number of sheets is interesting they may agree to import some for you. Third, ask the source, maybe for example WILA imports to Iceland or will give the address of a retailer able to ship you plywood. Brief it's a long search to find the good provider.

I have used a lot of Russian birch and pine plywood for boatbuilding a the beginning because of political circumstances these plies were very cheap, but after trying it for quality and strength.

I have used also Finnish plywoods WISA, very good.

Birch plywood is heavy but very strong, pine rather light and very good. These woods are rated not durable, like okoume, so I have used it epoxy coated. Excellent results, easy to work, strength and durability when well protected (as most plywoods....)

Very few plywoods are made with wood resistant to rot, or treated. Very expensive, always very heavy.

In Finland the brand WISA, owned by UPM, has a lot of plywoods some very technical. The internet site has lot of infos.
http://w3.upm-kymmene.com/en/engineered_materials/

The Canadian importer of Russian birch plywood has a lot of infos
http://www.thomescanada.com/html/plywood.html

A search by Google will give more.

An excerpt from To scarf or not to scarf may help you:

....."To conclude you can make a crude test of a plywood to estimate its quality.
1-Buy a sheet and count the number of inner plies 7 for an 1/2" and quality and thickness 1/20" mini of the outside plies (knots, discoloration, splits etc...)
1-line glues must be dark brown (phenol)
2-cut the plywood in squares of 4*4 inches and look for voids and other defects.
3-with a chisel try to separate the plies: the glue lines must be stronger than the wood itself.
4-take ten squares and boil them 1 hour. Delamination while boiling is forbidden.
5-Destroy one boiled square with a chisel trying to separate the plies: the glue lines must be stronger than the wood itself at least at 80%.
6-take 2 squares and make it dry totally in a oven at 120 celsius degrees. Delamination while drying is forbidden.
7-Destroy one dried square with a chisel trying to separate the plies: the glue lines must be stronger than the wood itself at least at 70%.
8-meantime reboil one hour more the remaining 7 squares.
9-Destroy one re-boiled square with a chisel trying to separate the plies: the glue lines must be stronger than the wood itself at least at 70%.
10-take 2 re-boiled squares and make it dry totally in a oven at 120 celsius degrees. Delamination while drying is forbidden.
11-Destroy one re-boiled and dried square with a chisel trying to separate the plies: the glue lines must be stronger than the wood itself at least at 60 to 70%.
12-Clean the kitchen and buy flowers for you wife. Don't forget to open the windows because of the smell."....

[teakcell]

The very very best marine plywood is the one:
-custom made for your precise needs: thickness of plies and plywood, dimension and plies cross as needed
- all plies made with teak veneer
- glued with phenolic type glues or epoxies

Plywood main principles in terms of structural strength: the thickness of the outside plies matters the more and the thinner the more plies in the core the better.

Okoume rots in my experience and wouldn´t use it for anything on a boat. Sepelle is superior and in 1088 you don´t need, or want, to encapsulate it. Don´t know anything about the Finnish or Russian stuff but intend to learn after this (thx). If one is talking of epoxy encapsulating, he had better be talking of layers of glass, as well. There are just too many ways to penetrate that epoxy "incapsulation" and then you have what - a piece of non-durable okoume in water, in a baggy?
As far as the rainforests go, I have always had a problem with we Europeans and Americans cutting down every damned living thing we can find then telling some third-world farmer we won´t (or can´t) buy his trees for his own good. A little like getting on some shoe designer, or whatever for building shoes in some armpit of the world that uses child labor - what, you´d rather that child NOT have a job? Starve, perhaps? Impose our standards on other cultures? Gentleman In Quintana Roo; As I write to you from the Destrito Federal (Mexico City) I have seen too much poverty, too many opportunities stolen by the Politicos, to believe now is the time to tell these people they can´t do whatever they need to do to survive. We want them to play by our rules but they aren´t even in the game...We lost "marine plywood" as it was born. It was made by one factory in Oregon by the Simpson Timber Company and was asassinated for the spotted owl so we could feel good about ourselves.

[rasorinc]

Hydro-teck is better to finish than Doug Fir http://marine-plywood.us/

Use Russian Birch:
https://www.dd-host.de/rueggshop/
Use Teak and holly:
same source
All stuff sold is to GL standards if it is AW 100, Shop has to guarantee!!! the specs in Germany
otherwise will be prosecuted.
ruegg is the main source of marine ply in Germany since ages, and you know, we don´t play if it comes to quality.
Forget the american rubbish, even for free!
Regards
Richard
Bruynzeel is not the worst choice as well.

Originally Posted by teakcell

The very very best marine plywood is the one:
-custom made for your precise needs: thickness of plies and plywood, dimension and plies cross as needed
- all plies made with teak veneer
- glued with phenolic type glues or epoxies

Plywood main principles in terms of structural strength: the thickness of the outside plies matters the more and the thinner the more plies in the core the better.

How much the m² ? fob Rangoon.........
Buy from 5000 m² / 6 mm - 9 mm - 12 mm onward

Regards
Richard

[jmolan]

Originally Posted by apex1

Use Russian Birch:
https://www.dd-host.de/rueggshop/
Use Teak and holly:
same source
All stuff sold is to GL standards if it is AW 100, Shop has to guarantee!!! the specs in Germany
otherwise will be prosecuted.
ruegg is the main source of marine ply in Germany since ages, and you know, we don´t play if it comes to quality.
Forget the american rubbish, even for free!
Regards
Richard
Bruynzeel is not the worst choice as well.

Sorry your URL above did not work. I am searching out the best Plywoods available, this is a good discussion. Can anyone steer me to a page that would show the various marine plywoods weights? Something I could compare against all the other factors? I want to build a multihull and the weight difference between Meranti (heavy) and Okume (lighter) is pretty big.

Oh gawd...

that was a really old one you opened.


Meranti is the far superior choice, due to the better properties per m² as per kg.
Though I doubt you can get a real meranti ply in Mexico.

Try the "wood explorer" database to get serious information, and have a good source of sawmills and timber suppliers before you start any project.

Regards
Richard

[jmolan]

Oh yea....so sorry about the old thread....I looked at it and thought it was just recently.....

Thanks

[cookie munster]

On the WBF people rave about Ocoume. Most Dutch prefer Ocoume over Meranti. Not sure why. Would be interested in your conclusion.

[tom28571]

Originally Posted by cookie munster

On the WBF people rave about Ocoume. Most Dutch prefer Ocoume over Meranti. Not sure why. Would be interested in your conclusion.

Meranti is stronger, stiffer, more durable (rot resistant) and heavier than Occume. Occume usually has a nicer face for finishing bright. Occume weighs 0.102lb/mm/sq ft. Meranti weighs 0.126lb/mm/sq ft. Meranti is cheaper than Occume.

If weight is not an issue, Meranti can be the best choice. Most of us do value the lighter weight of Occume and choose it for that reason. If a boat has 2000lb of plywood in it, using Meranti is like having three extra crew aboard that cannot be put ashore.

[jmolan]

Originally Posted by tom28571

Meranti is stronger, stiffer, more durable (rot resistant) and heavier than Occume. Occume usually has a nicer face for finishing bright. Occume weighs 0.102lb/mm/sq ft. Meranti weighs 0.126lb/mm/sq ft. Meranti is cheaper than Occume.

If weight is not an issue, Meranti can be the best choice. Most of us do value the lighter weight of Occume and choose it for that reason. If a boat has 2000lb of plywood in it, using Meranti is like having three extra crew aboard that cannot be put ashore.

Tom thanks so much on that, it is what I was looking for. Without trying to beat a dead horse, if I may. Is there any other plywood that is of the same high quality and has similar light weight as Okume? I have not been able to find a page that compares plywood.

Wood explorer is excellent, but I found nothing on plywood.