BS 1088 Occume plywoods

[Oyster]

Well this is more of a FWIW post for most folks but thought I would share this one with you folks. You will need to double click on the pictures to get the jest of the story. But both woods are the same material and speced out B.S. 1088 standards, but one with the label is 5 ply and the other is 7 plys. Of course I am using the seven ply, 9mm. But do ask when buying the wood, even though it may carry the 1088 label.

[Dave Fleming]

Mike, jes' for the hell of it, I went and looked at the Joubert that Shane uses. It has a different sticker on it and all the thicknesses from approx. 3/8 t0 3/4 inch are the multiple 7 or more ply.

Sticker is two tone blue no yellow in it at all.

[capt jake]

Every order of Hydrotec that we have been getting at the shop is different.  I mean totally different.  Some looks like Luan (which I am gathering is the way it is now).

Changing markets and supply I 'spose. ??

[Pipefitter]

Why is the occume better than meranti other than the weight issue? Seems odd that a panel made from a less durable species that costs more.
The meranti from world panel had no stickers but a red inked stamp. I ordered in 2 lots,6 months apart and the wood was nearly identical. 9mm had 7 plies. I know you guys are the experts but trying to make a choice on which to get was rather troubling.
Have you tried meranti Oyster,anyone else?What did you think of it?Was it a bad choice on my part?

[boatbuilder.org]

Occume has a definite advantage if there is a lot of shape because it will bend more easily and will make more of a bend before it will snap. For brightwork Occume also has a much nicer appearance than Hydrotec, and it is also lighter. It certainly does have it uses, but for most applications the Hydrotec is the better value. If a boat is built with the proper "WEST" construction there is not the durability issue with other forms of construction.
         ---Joel---

[Howard]

Any chance that there is some counterfeit stuff floating around?

Try going to Mexico and buying a real Cuban Cohiba. You can buy cigars all day long with Cohiba labels, but very few of them are Cuban.

What do the suppliers like Edensaw or Noah's say about it when the stuff turns up different?

[Howard]

Did some review of some of my saved sites. This one has some relative information:

http://alliedveneer.com/i...tm_campaign=marineplywood

Note the difference between the Aquatec and Hydrotec products. Perhaps some of the shipments got crossed up? And also note the color of the Joubert label.

What is Meranti in relation to Luan? This site says these are Luan based products, but later describes them as Meranti.

[capt jake]

What is Meranti in relation to Luan?

I have wondered that myself.  My personal feeling is that Luan is a 'catch all' term for a whole slew of species.  Kind of like 'mohogany'.  My personal feelings only.  With that said, it would seem that Meranti is a family within the 'Luan' catagory.

[Charlie Jones]

Well- first, Okume is NOT a mahogany- it's an african hardwood called "Okume" strangely enough.

Luaun as I understand it, is Phillipine Mahogany, which technically is in the cedar family, so it's also NOT a true mahogany in reality.

Don't know about Meranti, although when I was building my trimaran in the late 70s/early 80s, the company I was buying my Western Red Cedar flitches from also sold flitches of Meranti. This was NOT plywood- it was 1/8 inch thick veneers, for use in cold molding. They were flitch cut and could be obtained in long lengths, pretty much the same as the WRC.

Yesterday I picked up some Okume by the way- Shellmarine stuff. BS1088, Lloyld's certified- 6MM with 5 ply. It's also not 4 by 8. It's 49 1/4 by 98 1/2 inches. When you scarf it you wind up with a useable 4 by 8 after lapping.

[Oyster]

I understand the difference of Occume and Luan when it comes to rcognizing grains. My original point was more on the issues of veneers, which adds strength, but also the quality of woods or plywoods in this case, when it comes to high end and low end. Even some of the common plywoods, used in home construction comes, with thick and uniform plys, unlike the common filled  woods of the 9mm five ply Occume plywood with the B.S. 1088 stamp on it. I do not know the color difference in the stamp face, but the two are different even in the insides. The five ply came from another antique job.

[Dave Fleming]

Mike, the boat carpenter 'round the corner has only 7 or more ply Joubert ply as to the woods used....I haven't a clue.

Nice stuff as I look at it though.
And it all has that Blue Label as shown in the URL of the post above.

[Pipefitter]

The meranti smells different than the luan. The meranti smells just like a cigar box and from what I heard,cigar box wood was thought to be spanish cedar. The room that I kept it in smelled like a cigar box,when I cut it,even more so.

The one question I have never been able to get clearly answered has to do with the thinner outer veneers. On standard construction plywood,with most of it's veneers the same thickness,is a consideration when arranging the sheets in relation to the framing.The grain on the outer plies makes the sheet stronger in rip direction or it's length across frames or joists or whatever. Is this maybe why that some marine panels are said to bend funny? Is the last thicker veneer just under the outer thin one's grain going across the width of the sheet? If this is the case,it would seem that this could add to that starved horse effect of a plywood planked,framed boat?

[PAR]

Meranti is different from Lauan. Lauan is an Indonesian cedar and is now referred to as "Philippine Mahogany" primarily because of color and some grain similarities. Meranti is a cousin of the mahogany family, though more often then not, is now lumped into the "Lauan" group, which can include a number of different woods from that part of the world. Meranti once was the "Indonesian Mahogany" and quite nice stuff. For some unknown reason it's often categorized with the Lauans. Manufacturing controls and grading system usage, swings from reasonably good to none at all in many western rim countries, particularly China, the lot of south east Asia and the Philippines. Careful inspection of all plywood from these areas, especially if a "Philippine mahogany" is ordered.

Sapele is an African mahogany, typically with a wider grain pattern then other mahoganies, it also finishes very well and has good rot resistance. Okome is another African species, but not related to the mahoganies and it's properties have been pointed out.

Thinner outer veneers are a result of a finishing process after the panel is assembled. Construction grade ply doesn't need a high level of finish, so the outer layers are about the same thickness as the inner. On marine grade ply, the outer layers are machined quite smooth, which removes a portion of the thickness. When assembled these sheets had equal thickness layers. Cabinet grade panels have a paper thin layer of veneer applied, with much thicker inner layers. These sheets require only the aesthetic qualities of the outer veneer, not the structural properties, so the manufactures don't waist stock (the nice veneer) in a product that doesn't need it. Cabinet grades, typically don't have WBP glue and can't be used in a boat, unless used as a drawer front, for which it was designed.

[Pipefitter]

I guess my point was more to the effect that if both outer plies were thicker with the grain running longitudally,or even if the 4 plies of a 7 ply panel's grain was orientated in that way,their characteristics would be closer to that of a solid wood plank with it's grain running the same way from a bending in a curve across frames standpoint.Maybe that would make a difference in it's bending characteristics as well. I just don't know if this is an engineering consideration when designing a panel for marine grade or other kind of construction panel.

If when sheeting in a floor and you are a piece short and your only drop has the grain of the outside skins running the wrong way,even if it fits, it will be a soft spot between the joists compared to a drop with the grain facing the proper direction.

[Oyster]

Its hard to discuss the characteristics of every plywood, when you talk about bending and strength. There are two combinations that you should always look for in plywood. The inner plies need to be uniform in thicknesses, and have odd numbers of plies. This is not always the case.

You will find this to be one of the main reasons for bending problems along with weak plywood. The types of cores are sometimes not whats on the face, either. Some of the inner cores are not continuous cores, meaning seams and fill wood can exist. In that seam, there can also be a tiny void, that also lets go in that longitual bend, and cross grain orientation, allowing for the sudden snapping sound. In most cases, attaching the name "marine" to the plywood, may give you the proper glues, but may not give you good plywoods. Some of the hardwood faced plywoods, are pretty crappy, because some cheaper priced stuff use cores that are sold throughout the world for laminating single veneers and sold to the industry. In a lot of these plywoods,  there is not a resorcinol glue in the inner layers, either.