Meranti Problems

[DISTELTK]

I built a BRS  15 and am enjoying the boat.  I built it to use and my finishing skills are not of a furniture maker.

I built if from Meranti plywood, my local supplier had just started carrying it.

I had some delamination problem with the deck sheet.  I had fixed this with cutting down to solid wood and patching with thickened epoxy and repainting.

I contacted my supplier about the problem not wanting any compensation just to let them know of the problem.  The boat has been unused for a few weeks and getting it ready for an extended trip with a group of friends.  I noticed a 6" bubble on the port side near where the  reefing mast support is.  The entire hull inside including inside the seats and out were coated with epoxy before painting. 

Damn I will now have to grind the area down and patching this also.

Has anyone had a similar experience with this plywood, it was stamped with the

proper id for marine usage.

I have built with Acoume, and BIg Box Luan and never had this problem.

O well the spouse is beginning to rebel against building any more boats.

Spending that much money and having them fall apart is not in her agenda.

Tom D.

[Tom Lathrop]

The problem is not related to the plywood being meranti.  It could have been any other wood species.  Gaps, both small and large in the layer of glue between the plies is what causes  most delamination.  The problem is the quality of manufacturing and your supplier looking for the cheapest source.  This is becoming more and more common and the fact that they stamped it "marine" only means that they own a marine stamp.  No one is policing the labeling of plywood other than the manufacturer themselves.  The only thing protecting the buyer of plywood is the materials and care that the manufacturer puts into it. 

[Designer]

I have used marine ply from many countries and I have had quality issues from most of them. Having been in a few plywood mills, I am amazed that we don't see more problems. I have seen some good ply and some very bad ply from China. I have a sheet of okume ply here from Joubert in France who is a top manufacturer that has a 6" bubble in the middle of the sheet.

It would be heart breaking to have as many issues in one project as you are having. Usually I can pick up on the delamination before it is built in and reject the sheet.

We have a local manufacturer that sells "marine ply". The cores are made in Brazil and are riddled with voids. They put on very thin faces here. The glue is not even phenolic. When I gently suggested to their rep that they should change the marine label to save law suits, he became quite indignant.

[DISTELTK]

It was stamped BS1088 Hydroteck.

I made the deck from the same sheet the side panel was cut from.

I have used Okoume from the same supplier for my Birder II and no probems.

Next boat ??? will use Okoume

Thanks for the replies

Tom D.

[markja]

I had a problem this year with 1 of 4 sheets of Okume Joubert BS1088. I had some delaminating, too and didn't notice it until the boat was taped. I took a depp breath, and just dug out the loose area and filled with epoxy. Found one more small bubble after the first splash and forced epoxy in there too. Several launches later I haven't noticed any problems. I guess we just don't expect defects when we buy quality plywood. I sure wasn't trying to scrimp on mine. Oh well. I went around and tapped with finger all over the hull. The loose plies sound quite a bit different. Good luck.

MARK

[Dale Niemann]

Marks last comment brought up this question.

Graham/Tom,

How do you go about determining bad ply before you build the boat.  Do you have any suggestions for us?

Dale

[Tom Lathrop]

Dale, I don't know of a guaranteed and simple way to do this.  I hold a sheet up to near eye level and sight across the surface for any raised areas that can be a delamination.  Also tap lightly across the panel and listen for hollow sounds.  If the delam is deep inside and not very big, it may not show up until cut across.  While many are extremely concerned about any void inside a plywood panel, it may not be the disaster that they think.  Not to say that voids are good but they just don't guarantee a future failure.  After all, many boat hulls are built with materials that have intentional air spaces inside, Nomex for instance.  Of course, we'd rather that our suppliers were more diligent with their quality control but, as we often have to face, it is what it is and we have to deal with it. 

Real timber has all kinds of problems, hidden deep inside as well as on the surface.  Treat plywood the same way and you should catch most issues before they get too far.

I've never seen a problem with Joubert plywood and am distressed they too have fallen on the quality scale.

[Designer]

I agree with what Tom said. If I can tilt the sheet to the light with my eye close to the edge I can usually see if there is any swelling on the surface, sweeping my hand across the suspected area I can hear the tone change to confirm that I really saw something. This mainly works on the outside veneer.

[Designer]

Yes I do. Every sheet is handled several times and you can't get out of the habit of scrutinizing the sheet after doing it for so long. If a flaw comes up after the part is cut it is rejected.

[Apteryx]

No flaws in the material I got from you, Graham, not that I can see - really nice wood.

Wish I could say I had a boat already, but so far, just a lot of overtime and work.  I built a nice workbench, that was something I needed to do, but I'm quite ready to start on real boat construction.

I imagine I'll get started with gluing scarfs this weekend, maybe while I build cradles.