Gaboon or Okoume plywood

[Doug Canada]

Could I get a "short summery" of Gaboon or Okoume plywood? (grain patterns, cost, availability, ease of working with, etc.)

What are the "strengths & weakness" of the marine plywoods?

With the "qualities of epoxies" today, does it really need to be a "marine grade" for boat building?

Doug

.

[Cuyahoga Chuck]

When you get into the upper classes of marine plywood all the contenders are made with tropical hardwoods. This is because tropical trees grow year round and therefore produce a more more homogenous and stabile wood.
Okoume has become a standard because it can be plantation grown and it verneers well.
When boat types talk about marine ply they, invariably, bring up British Standard plywood ratings (BS 1088, BS 6566, etc.). These standards have supposedly gone by the boards but the principle involved is still valid. The best plywood is built to an enforced standard. Items like, number and types of verneers, types of glue, quality of verneers, allowable amount of voids on inner plies, orientation of verneers, etc. are all called out in a standard like the old BS 1088. Of course, anyone can get a rubber stamp that says BS 1088 so it's best to have a supplier you trust. The best and costliest suppliers put a trademarked label on every sheet.
In the US, plywood is made to an association standard. Manufacturers in various parts of the country have banded together and set up their own rules which may or may not be enforced.
In general, okuome produces the lightest of the marine plywoods. It finishes bright, well and easily, and is not known to check like fir. Of course, it is not as stiff or as bulletproof as fir.
Where I live BS 1088 in ¼" is $70 a sheet. But for ease of use( it bends a lot easier than any domestic ply) and ease of finish ( no wild grain pattern to show thru') it's worth the money just in terms of saved labor.
I build nothing but small boat (pirogues, kayaks, dinghies, prams) so my epoxy requirements are not large. I stick with name brands and don't go looking for rock bottom prices. Having a well known label on your glue means that you can get answers if something untoward pops up. I use West Systems and Systems 3 and would not hesitate to use MAS if it was available to me. If I were going to build a large S&G hull I might go shopping for a low cost supplier but would check references carefully. Talk of buying 'glass or epoxy from some unkown on e-Bay make me cringe.

Charlie

[Graham Knight]

Gaboon and Okoume are the same thing, just different names for the same timber.
It's the lightest of the marine plywoods, less rot resistant than others so needs to be well maintained, works well, bends easily, not unattractive but not as nice as more expensive plywoods.
Price may depend on where you live, but generally Okoume seems to be quite reasonably priced.
I've built my new Acorn skiff using it (see photos in my "oars" thread), I didn't consider it good enough for a bright finished exterior so I'm paining that, but the interior doesn't look bad at all.
The strengths of marine ply are rot resistance to varying degrees depending on the species used, strength because it has no voids in the inner plys, and waterproof adhesive (WBP).
Other plywoods such as exterior are WBP (water and boil proof) too, but often have quite large voids in the core creating local weak spots, and may be made from less rot resistant timber species.
Personally I wouldn't build with anything other than marine grade, there's so little price difference between marine and good quality exterior it's just not worth it to save a few Pounds/Dollars/etc...
Some guys build small boats with exterior ply, but you're using so little timber in the first place the saving is insignificant. You might make a substantial saving with the amount of timber in a big boat, but a big boat will be subject to big stresses, and with all those hidden voids...forget it!

[JimD]

Okoume looks like this:

http://www.imagestation.com/picture/sraid200/p3929f3e19989d8c19325c0a3b26073fe/f078ff3d.jpg

The image is from Noahs Marine Supplies. Epoxy and varnish will make it look darker, richer, shinier. Noahs are in the Toronto area and is one of the best known marine suppliers so a good place for you to shop.

Here is a link to their website for a great comparison of various plywoods:

http://www.noahsmarine.com/Canada/Plywoods-can/ply woods-can.html (http://www.noahsmarine.com/Canada/Plywoods-can/plywoods-can.html)

Like C Chuck I also build small plywood boats and okoume is great for that but keep in mind the rot resistance is not great so I personally would be disinclined to use it on a larger boat that spends most of its time in the water although many people seem to have done so.

I'd stick to a name epoxy. I've tried a few brands and am currently using RAKA but you have to order it from Florida. Noahs sells East, West, Mas, and Industrial Formulators. My personal preference is for a 2:1 mix ratio forumla, not a 5:1 because I find it easier to accurately measure. (I hope this thread doesn't turn into another tedious quibling match concerning epoxy forumlas, mix ratios, pumps, etc. It's been known to happen)

[ 01-22-2006, 12:37 PM: Message edited by: JimD ]