Luan reliability?

[dockdave]

love to read this stuff. LOL funny at times. Inferior products result in inferior products. Ask yourself what are you after

[rasorinc]

Never could find a supplier of bamboo ply who could tell me what adhesive was used. Here is a report on BC cedar

try this one http://books.google.com/books?id=aiw...um=8&ct=result
BC ceder is not a good wood for boat building. Alaskan Ceder is. Bamboo fibers are one of the toughest materials around. Ever try to cut dry bamboo?

[bilgepump]

To dockdave I'm after a boat not more time saving to afford the suggested plys, like I said earlier I'm not building something I plan to sell or finish to bristol standards if the boat lasts me a year or two then in my eyes I have succeded. Have your laugh but ask yourself for your first build would you jump right in and start shelling out 80 some odd dollars for a sheet of plywood? To rasorinc I recently came across a site that sold it but it was very exspensive and hell its tough just cutting through green bamboo and thanks for the tip I'll look into it more

[timothy22]

Take heart bilgepump, some years ago I built a 15 foot skiff out of good quality luan doorskin. No fiberglass, no resin, just good old 3M 5200. 2 coats linseed oil thinned with turps, 2 coats oil based house paint. It was flexible, but light. I carried it on my car top rack and rowed it all over Ft Lauderdale's canals for three years and sold it for twice what I had in it.

[bilgepump]

Thank you timothy22 if that was some years ago I imagine that today due to more usages for lauan the glues and overall quality have been improved thanks again its good to hear a voice thats not a naysayer!!

[popperspop]

For at least the last six months, Lowes,here in the states, has been selling a Chinese hardwood plywood for underlayment applications. I boiled two three inch coupons for an hour with no delamination . I did have an area about 3/8 " in diameter that swelled approx .020. These panels were made with three equal thickness plys and two paper thin veneer skins . Price for 5.2 mm x4' x8 is $10.78 per sheet. Manufactured by Samling and labeled Hardwood Plywood
Exterior (12549)

[rasorinc]

Did you check to see if there are any voids between the ply? The boil test is fine and the price is good. Just check for voids. My 2 bits Buy one sheet and cut it in half while telling them to hold whatever amount you are going to buy for a day.

[ancient kayaker]

I used Home Hardware (Canadian version of Home Depot) door skin (1/8" luan plywood) for my first few boat projects. Initially it was quite good quality, glued well, looked nice varnished etc. and very cheap.

However the quality dropped alarmingly between 2004 and 2007 at which point I changed to marine ply. the luan was kept in a dark, cramped location in the supplier’s warehouse, impossible to inspect or select. One sheet had its outer veneer flaking off, another nice looking sheet developed 8" diameter blisters when painted due to missing glue. I could scrape the surface ply off with my fingernails. It was so bad that the last boat made like that was put in the water once then junked. I only use it for templates now, but like others it helped me to learn hands-on.

Luan ply was a lot better years ago, I recently replaced an exterior door made with the stuff that had delaminated but only after 25 years, Northern exposure.

The price of marine ply here in Canada is a bit savage. I recently got lucky and picked up a modest stack of water-stained ply for below half-price, courtesy of last Winter’s heavy snow. It is perfectly sound with mild discoloration at one or two corners; That should keep me busy for a year or two. it’s an ill wind ...

A word on glassing over ply. The glass provides tensile strength. On its own it isn’t thick enough to support compression unless the ply underneath keeps it from buckling. However, put glass over ply that has a void, a punky center layer or unglued surface veneer and bend the ply so that area of glass is compressed, and it may collapse suddenly and catastrophically.

[PAR]

That's funny you mention that Terry. I was fitting a coming last week on one of my designs. Of course it has a big sweeping curved coming, that looks lovely, but requires considerable template skill to get a pattern. I roughed in a 1/4" template, bent it into place and it stayed for about 15 minutes. Enough time to trace the deck line and the side deck carlins, when BANG, the sheet just gave up, breaking across the exterior grains. Clearly a void that I didn't see.

Interestingly enough a 1/4" piece of Okoume, which I applied a little steam to with a hand steamer (one of those things you use to take wrinkles out of cloths and no she didn't catch me) went in fine and has been living there ever since. The image shows the curve I'm talking about, though it's not installed, the carlin is there. It's not a severe curve, but enough to find any flaws in home improvement store luan. I, like most experienced builders can't use luan any more, it's just template material now.

[ancient kayaker]

Nice boat, Paul. Picture didn't come up though. These days I use regular store-bought ply for temporary forms and flat templates only. As you found, it doesn't bend uniformly.

I much prefer Baltic Birch which comes in 5 x 5 sheets, in this area at least, nice finish and takes a pencil line well. As an experiment I planed a couple of intersecting 4 degree bevels on a piece to see what I got. The laminations are perfect and the glue lines unobtrusive. The different directions of grain catch the light in interesting patterns and I might use it as a decorative feature on a canoe I'm finishing, if I can find a stain that disguises the glue without clogging the grain.

[Steve W]

I built many stitch and tape dinghies years ago with Luaan underlayment
which was great stuff and has held up well,nowdays its crap and delaminates sitting on the rack at the lumberyard.I would hope that the OP has long ago built his kayak,used it ,sold it and built another by now,this time out of 3 or 4mm instead of the 1/4" he was proposing,what with glassing it inside and out the thing would weigh a ton.
Steve.