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Okoume or Meranti


Don Silsbe
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Since these are built in the basement of a former school, the largest we'd build would be a 15. The concern is less about structural strength. It is about abrasion and puncture resistance-- durability in that regard. My colleague buys the wood. I'll have to ask him about wood source. When I built the Willow kayak, I got it from CLC.

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Dave, this is getting to be a habit. I agree completely with your comment.  'Lively' is built of Okoume and only the seams were glassed which is I think what Dave meant.  Glass and epoxy everywhere adds a lot of weight

 

Thrillsbe,  If you want abrasion resistance on the bottom add glass on bottom only. I have been pulling 'Lively' up on FL sand beachs for about 7 years now with very little wear.  However, I did polyester cloth the keel. I believe Graham recommends SS or bronze on the keel but I did not want the screw holes causing future problems.

dale

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Okoume is about 20% lighter than meranti, which is enough to warrant it's use. Okoume is not as stiff or as stronger as meranti, so if you plan of beating the crap out of the boat, meranti is the choice. Both species would be well served with a sheathing, but it's really about the care the boat will see. If it's well maintained, it doesn't mater which you use, except for the weight.

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I was surprised a week or so ago when I was attempting to move Peggy-O out of her "home" for a couple hours by myself, and then when moving her back in and over the very small step I had to push her over caused the cradle to break, the boat to crash and about a #12 screw from the cradle punctured right thru the hull. I have 10ounce glass and several layers of epoxy on the hull. I drilled the hole clean, taped one side and added epoxy a couple times and then thickened epoxy to patch. My point is I was left with some concern about puncturing the boat rather easily on rocks or whatever. This does not speak to the subject here but was just curious about your thoughts on this.

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Lennie:

 

I imagine the same thing would have happened to almost any boat.....fiberglass, injected plastic, etc. They are tough when it comes to glancing blows and scrapes, but are not impervious to direct hits from sharp, pointed objects. None of them would be. Well, maybe steel. The good news is even if it does happen, it is an easy fix. Not so much with the others.

 

As for the rest of the discussion about the differences in plywood, and which is "better", I think you have only scratched the surface. That and "better" for what?

 

The two plywoods have different densities (weight), and as PAR suggests meranti is heavier. In most cases with wood, denser correlates to stronger. That also means it (meranti) won't bend as easily, so if you are doing a tortured plywood build (Spindrift, Core Sound, etc). Okoume will make those sharp, twisted bends easier. Since lighter in weight generally corresponds to faster on the water, it is likely that two otherwise identical boats (in this size range), the Okoume boat will be lighter, and thus faster.

 

The two of them, when finished bright, have different colors. Meranti, depending on which species, will finish anywhere from a dark chocolate similar to black walnut, to a darker reddish hue. Okoume is lighter in color, what some call salmon or pinkish, which is closer to cherry.

 

The fibers on meranti are coarser, which means it will splinter more and is rougher to handle. I usually wear gloves when I'm handling it. I think of those fibers as stringy little mini bundles of rope or fiber, except the splinters are sharp little shards that will stab you. What is interesting when coating meranti with unthickened epoxy is to see all the air bubbles pop up. Look close and it almost resembles the effervescence of carbonated soda. That mini bubble action will go on for several minutes as the epoxy displaces the air bubbles in the wood fibers as it works it's way all the way down to the glue line. So even when glassing, you need to give it some time for the outgassing to finish before you apply tape or glass, or else face having air bubbles trapped in your mix. Not a bad thing as it is really working deep into the wood fibers, but something to account for.

 

Most discussions of the two focus on "durability", which when you dig into what that means, is that okoume gets poor ratings due to potential for rot. With a proper epoxy job, with everything fully encapsulated, water won't be getting in, so that would seem to be a non-issue.

 

Meranti weighs about 20% more, but costs about 20% less.

 

Mertani is sold as one of two choices: Hydrotek (BS 1088 standard) or Aquatek (the lessor BS 6566 standard). However, most of these will be found to be made in China, so is a real crap shoot as to quality. Like a box of chocolates, you never know what you are going to get. If you plan to use much of this, and can't go pick it up and inspect it yourself, find a reputable supplier and ask them to send you a sample of what you are going to get. Ideally, the piece with the nameplate stamp on it.

 

Okoume on the other hand, can be obtained from many sources, and as long as you get Joubert, etc., you know what you will be getting (good quality).

 

There are probably even more differences, but those are the ones that come to mind.

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Most of the Hydrotech and Aquatech plywood the USA gets is from Korea and Vietnam, not China. Now, China does export a fair bit of plywood labeled like this, but after the real crap that showed up a few years ago, some still on the market, most of it is now sold as something other then these brands. The trick with these two brands is to find the supplier, such as Wolstenholme (for example). Some of these suppliers are less than scrupulous, but these can be searched out. Real Hydro and Aquatech stock will have a round stamp from most suppliers, some have a printed label. It's also important to inspect sheets and learn what to look for.

 

Lennie, a light 'glass sheathing (10 ounces isn't much fabric) over a thin sheet of plywood, is no match for the mass of the boat, times it's acceleration (formula describing force), concentrated onto the business end of a wood screw. At the end of the screw, at the very point, you likely had hundreds, if not thousands of pounds of force per sq. inch, mostly because the contact patch was so small. This is typical of penetration analysis and only a layer or two of Kevlar might have prevented the holing. Physics sucks sometimes . . .

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Paul:

 

These are the two brand stamps on the Meranti I'm using. The supplier I ordered from didn't know the exact origin, but didn't think it was China. That was before I ordered. When my order arrived, the only ID on it was these stamps. When I attempted to track them down, the best I could tell is they were both made in China.

 

First I've heard of Korea and Vietnam. I had heard the best stuff was coming out of Indonesia, which by the way, is a big place.

 

My point being is that on the surface, Meranti seems to be an excellent product and a good choice for the right kind of build, but there is a lot of murky water to navigate if you want to use it.

 

If there is a known "best" supplier (importer), and they will tell you what brands are best and where to get them, that would be good information to know.

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BTW, when ordering Hydrotek, I've seen numerous cases where the suppliers indicate that Hydrotek or Aquatek will be either Meranti or Keruing, the latter being a heavier, stronger, and apparently superior product over Meranti. In this case, it appears they get what they get, and when they ship your order, you will to.

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The "Dragon" stamp is from Dragon Plywood in Sumatra (Indonesia) and the typical importers are Paxton and Hardwood (Frank Paxton Lumber, Denver and Hardwood, BC, Canada). Dragon has a pretty good rep.

 

The Fuji stamp is FUJI is out of India and fairly common in the USA, carried by several (many) importers, likely because of price point.

 

More important than the importer or actual supplier is physically inspecting the sheets. Learn how to look them over (it's not hard). You're quickly figure out how to check for voids, overlapping veneers, appropriate veneer count and relative uniform thickness, etc. After the 1088 debacle a few years back, many of the northern Pacific rim suppliers trying to pass off their junk, cost them dearly, so I'll bet a few beheadings and lashings (don't kid yourselves, they're serious over there) occurred and they're trying to win back lost market share.

 

Yes, Indonesia is the largest supply of meranti sheets right now. Knowing your supplier helps greatly. I know if you get plywood from Graham, he'll inspect each sheet as it's delivered to his shop. Joel at Bateau.com will do the same, so you'll get good stuff. World Panel is just 15 miles from me, so I can personally go through each sheet as I load. Make friends with your supplier, get to know their personal, so you can get the best stuff available.

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