Okume or not?

[flydog]

Going to build a lapstrake sailing dingy from plywood. Choice of wood here in Atlanta are few. Either 3 ply AA fir, or okume. I was thinking of using the okume with an epoxy saturation because of its low durability and rot resistance. Any comments would be helpful. Thanks!

[lewisboats]

lots of boats are built that way. It is a proven method.

Steve

[Chris Ostlind]

Flydog,

When you say saturation, what exactly are you describing?

Chris

[flydog]

The saturation technique is to basically use a low viscosity epoxy that wets and soaks in the wood to preserve it.

Steve

[Chris Ostlind]

Flydog,

I'm not trying to be a hair splitting weenie on this subject, but every time I hear the saturate term used for the painting-on of epoxy to the surface of a plywood hull in construction... I get this picture of huge amounts of epoxy being used to totally flood the wood to its capacity to carry fluid. I picture a sponge floating in a sink full of water until it is so full, it can't absorb another drop

Sicne that isn't really happening at all, I wonder if there isn't a better term for the process of pre-wetting the surface so that the cloth is not resin starved once the glass laminate is applied?

A truly saturated wood core would weigh hundreds of pounds more than planned and seriously effect the displacement potential of the boat and its carrying capacity.

Chris

[JR-Shine]

Okoume will soak in a little epoxy (thin laminating epoxy), My guess would be around 3-4 oz. (weight) per square yard. Its not very much. "Encapsulation" is what your after.

[PAR]

I'm going to chime in because an often over looked aspect to epoxy encapsulation (the only true way to seal out moisture) is the additional cost, materials and effort it can place on a project.

Penetrating epoxy will soak in quite well. Laminating epoxy, if particularly thin or heated (or both) will do almost as well.

A traditional lapstrake dinghy is a wonderful project. The challenges to the builders skills can be rewarding (and frustrating), but the result is a beautiful set of sweeping laps that add a touch of grace and style to an other wise bland hull. It's one of the more difficult building methods and repairs are equally difficult, but the results speak volumes.

An epoxy version of the same craft can double it's costs, when you count the additional effort and materials. I sometimes find it had to justify these costs in time and materials. Of course glued lapstrake construction couldn't be without plywood and epoxy, but that's a different animal. On larger craft, epoxy can have a place, but in smaller boats I have problems with explaining it's use.

Shaving up the laps on a cedar sailor is very enjoyable. Chasing drips, scrapping excess, filling weave, fairing, filling, filleting, messing with goo, trying to get it on the work before it smokes in the pot, etc. isn't my idea of enjoyment in small craft construction. I've repaired many lapped craft and have found the epoxy ones didn't last any longer then the well care for traditional versions of the same.

For what it's worth . . .

[catsketcher]

My two cents worth is that Okume (we call it Gaboon in Australia) is a rainforest timber and that most of this timber is not sustainably logged. I love sailing to great places and feel it is incumbent on us to make our boats out of materials that don't degrade beautiful spots somewhere else in the world.

Plantation fir will make a great boat that is a little heavier. I use plantation Hoop Pine in my catamarans and they work very well. It is 530kg/m so I am a little heavier but the extra weight does give you extra strength so you can reduce some scantlings a little.

cheers

Phil

[Raggi_Thor]

I am ambiguous (do you say that) regarding sustainable woods, rain forests etc.
When we buy okume, maybe most of the money end up in some french pockets, but some of it also go to the workers in Gabon. They certainly need it. We (Norwegians) cut down all our pine woods and sold it to the Dutch and British a few hundred years ago. Now we are not willing to let 1% of the forests be untouched here. Is it fair that we ask poor people in Africa to let their forests be untouched?

[lewisboats]

Originally Posted by Raggi_Thor

I am ambiguous (do you say that) regarding sustainable woods, rain forests etc.
When we buy okume, maybe most of the money end up in some french pockets, but some of it also go to the workers in Gabon. They certainly need it. We (Norwegians) cut down all our pine woods and sold it to the Dutch and British a few hundred years ago. Now we are not willing to let 1% of the forests be untouched here. Is it fair that we ask poor people in Africa to let their forests be untouched?

Ambivalent is the word you are looking for. Means neither here nor there...of no specific opinion pro or con. I tend to take the same road. I don't particularly like the idea of stripping the rain forests and jungles but the ply I can lay my hands on is Crap otherwise. I wish there was a way of farming the most useful stuff instead of raping the natural sources.

Steve

[hansp77]

I don't think there is much of an argument for providing income for the locals.

ignoring the ecological perspective (or critique),
If the forestry companies were community owned and the money earned actually went into providing real assets and security (for the biophysical ones they are removing) then that may well be the case (and could be in particular places).
But most of the global timber industry is far from that.
Often getting considerable government subsidies and inducments, with rediculously cheap access to land, the actual benefits from the deforestation spread very thin through the comminity/economy/nation compared to the irreplaceable natural assets that are removed.

The timber industies are masters at influencing government policy and public opinion on how beneficial its practices are to communities/regions/nations. They often blame environmentalists and conservation efforts for taking away jobs and destroying communities- yet every chance they get to introduce a new technology that will reduce labour time and workforce size they leap at.
And then what do they do when the forests are gone?

I am not saying that we shouldn't cut down trees. But the way these guys are doing it- its a fire sale.
In rich developed countries with established conservation politics this occurs-
it third world or developing countries it is just that much easier to trully exploit the situation.

That said, I used pacific maple (meranti) marine ply on my boat.
It was about the only suitable thing I could get and or afford at the time, and I needed it too fast to hunt around.
I feel a bit guilty about that. Next time I will try to be more aware.

It is just a shame that we can't be a bit more precautionary and considered on our forest harvesting.
If we only harvested forests at the rate that they grow (from memory about 3-4% p/a ?) then we could have our cake and eat it too.
Instead it makes better economical sense to clear-fell entire regions and invest the money where it will grow at over 10% p/a.

I can't escape the feeling that the way we go about forestry is like somone walking into a new car lot and melting down the lot to sell as scrap metal.

These things and their ecosystems have a much higher value than we are ascribing them.

Enough of a rant from me.

I love trees,
but I also love timber...

[Crag Cay]

I think there are very valid reasons to be concerned about the use of tropical hardwoods. Apart from any ecological problems (and I'm in no way belittling these), the sale of plundered forest products is, along with diamonds and other commodities, frequently used to prop up several unsavoury regimes and fund protracted wars. The 'Geographical' magazine found much of this timber was corruptly passed off as 'from sustainable sources' and traced it to several wood yards in the UK.

Whilst the boat building use is only minor compared to construction or outdoor furniture, I feel it is incumbent on us to be careful. I don't spec any tropical hardwoods for the interior of boats and restrict its use elsewhere to the absolute minimum. I have found that the 'teak substitutes' for decking, (preferably the cork based ones), are more than acceptable in durability and appearance.

[Jimbo1490]

The world has been, on the whole RE-foresting for over a century now. The real reason forests get cut down (and not allowed to re-grow) is to create arable farm land. Modern farming methods have increased the yield of farmland so dramatically that year after year more farm land is idled and returns to forest. Re-foresting takes only 50-70 years, NOT 1000's of years as many green whackos would have you believe.

Now the same green whackos have been pushing for decades to limit, curtail and eventually ban the modern farming methods. We can probably afford to do that in North America and Western Europe, for we are relatively wealthy. But what about the developing world? Without modern farming methods, crop yields will be much lower, with the resulting pressure on forests returning.

Read Bjorn Lomborgs books! He is the man!

Jimbo

[Chris Ostlind]

So, Jimbo...

Would it also be fair to refer to anyone not concerned with the environment as an Industrial Whacko?

Come on, man, you can do better than that when you communicate.

There are salient points on both sides of the issue. To ignore one side in favor of the other, simply because you like the rhetoric and tag lines, is more than insincere, it borders on the foolish.

We get one little blue ball to play with. When that is done, so is everything we cherish not to mention desperately need for the essence of life. Manage it well, be responsible to future generations and be respectful of those who have different ideas.

And no, I'm not a Green Whacko, to use your terms.

[mulletbucket]

To answer the question about okume. Yes use it, we've used it here in North Carolina on our custom boats for some time with no problems. Be sure to buy standard 1088.