Marine Ply - Okoume or Douglas Fir

[Terra Nova]

Our fir marine is rather inferior.

The French okume equivalent to Bruynzeel plywood (Jonglert?) has been my gold standard for decades. Meranti is great, and usually cheaper, but considerably heavier.

MDO I find useful for many projects as it is cheap and widely available. But I would never use it in hull construction.

[HopCar]

I've built several small boats from regular marine plywood. It has worked out fine.

I've never had a chance to use one of the fancy plywoods so I can't tell you if it is any better.

The skiff on the trailer was built from Glen L plans. The Everglades Pole Boat was built from drawings in the book Glades Man. Glen Simmons, the man who wrote the book was a retired alligator poacher when I met him. He didn't know you couldn't bend plywood like that. We had to soak it in a hot tub overnight to get the bow to bend and twist like that.

[Terra Nova]

Ho--great projects.

[mitiempo]

Originally Posted by Terra Nova

Our fir marine is rather inferior.

The French okume equivalent to Bruynzeel plywood (Jonglert?) has been my gold standard for decades.

Joubert. Great product, easy to work with, no voids, face veneers perfect and without patches. The cost of the wood is a small part of the project so it makes sense to use the best.

My local supplier, Westwind Hardwood in Victoria does not sell marine fir ply as there is not any of good quality available.

[Terra Nova]

mi--that's it. Such wonderful material to work. Strong and lightweight.

[coastalexplorer]

Okume marine Plywood is the prefered material for cold-moulded hulls because it is lightweight, & bends to shape easily. It has very low rot resistance because it is a soft wood with a texture comparable to hard balsa wood. Thus it soaks up epoxy resin like blotting paper, (which some may remember from the days when we used fountain pens in school) My Coast 30 sailing yacht hull built by Tim Tuulos was built from it in 1982 and has no rot because the wood fibres were saturated in epoxy resin. A few weeks ago in port Townsend Washington we saw a round bilge cold-moulded dinghy in a boat building shop that was quite the work of art. So it is quite doable to cold mould in small sizes.

I have worked with the stitch and Tape method before, and personally I would use a different type of plywood for that. perhaps Maranti,

[admiralslater]

My brother and I built our first boat together in 1984 a Pdq 27 which our Dad designed for us. It was built with Fir good 2 sides plywood. It is still happily sailing today. It was also polyester glassed boat and has never had rot.
I think the fir will be fine for your Dingy. We have Dingys in our club built of door skins, that are 10 years old. BTW all the boats are on moorings so the Dingys do get used

[Pestman]

If you are fixing any wood or have bare wood, a couple treatments with Bora-care will stop fungus for years and years. Super safe to be around and bonds with the wood so is aquatic safe too. You can paint over it too. The more humid the wood, the farther it moves into the wood.

[Cheechako]

The non fir options are much nicer to work with for sure. As stated it hardly matters once epoxy coated. But the Bruynzeel and other products with more layers of veneer just cut nicer with less fuzzys, peels etc.
I still don't know if Marine fir ply is actual Fir or Hem-Fir. I've always heard it's the same as exterior fir ply except no voids allowed.

[Delancey]

The American Plywood Association specifies either Douglas Fir or Western Larch for marine grade panels. Like Douglas Fir, Western Larch is classified as moderately durable but has slightly higher modulus of elasticity and crushing strength than DF. Okoume is considerably weaker and not considered rot resistant.

Don't get me wrong, I think there are some nice okoume panel products out there but don't kid yourself thinking it is as strong or as durable as a domestically produced panel.

[rgleason]

Curious, what design?

[grae]

Thanks chaps for all the advice, so it seems I have the following choices:
- douglas fir - cheaper, heavier,less finished but rot resistant
- okoume - dearer, lighter, finer finish but not very rot resistant.
- carbon fibre - nice and I would love this but not really in my budget unfortunately!'

having said all that I think it's likely to be Okoume with a lot of penetrating epoxy prior to build

as do designs, I whittled it down to two, after lots of research online, between the pbo pup which I would have to alter the design to 'nest' or a Danny Greene's Chameleon, and Danny's design is very well favoured so were going to try that as it seems to tick all the boxes I need.

Again thanks for the advice.
Grae Morrison

[Delancey]

Missing from your pros and cons summary- Douglas Fir stronger. Okoume weaker.

Lot's of quality boats have been built using epoxy encapsulated okoume. You can do a lot to enhance the durabilty and strength of your boat by sheathing both the outside and inside with a layer of fiberglass.

Of, course this will add both cost and weight to your project but in for a penny in for a pound.

[Lojanica]

I had a bunch of "scrap" 6mm Meranti. Made a bunch of stuff. Epoxy coated in and outside and then taped all the seams. Very strong and waterproof.

I think fir is better for structural cross member type stuff. The meranti has a beautiful fine finsh and few if any voids. Epoxy takes care of the "rot" issue. Meranti is heavy though.

[Terra Nova]

As far as this discussion:

If you want a lightweight boat, best quality/strength/weight is okoume or equivalent.

If you want it stronger and don't mind more weight, use meranti.

Choose fir if you want cheap and can live with horrible slivers and splintering, and don't mind the less well balanced construction (3-ply vs 5-ply, on thinner plywood. Both of the above are vastly nicer to work with. And provide for a much more quality looking product.

Use WEST system epoxy, or equal, to prevent water intrusion.