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19706Re: Observations re: Underlayment plywood from China

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  • ted_major
    Sep 2, 2009
      Last summer when I built my QT skiff, the local Lowe's had ultraply for $20 a sheet, and that's what I used:
      http://www.flickr.com/photos/ted_major/2729172875/in/set-72157606527304335/

      Tidmarsh

      --- In Michalak@yahoogroups.com, "recree8" <arvent@...> wrote:
      >
      > Sounds like a great choice David. Thanks for sharing.
      >
      > Ultraply is made in USA so I stand corrected. You got for $20 a sheet?
      >
      > http://www.morelandcompany.com/ultraply.htm
      >
      > Nels
      >
      >
      >
      > --- In Michalak@yahoogroups.com, David Cassidy <d.cassidy@> wrote:
      > >
      > > I built an AF3 using UltraPly (launched last fall after 2 summers of
      > > building), and there is at least one other person on this list who
      > > built the same or a similar-sized boat with it several years ago. I
      > > found it to be really nice to work with- never found a void. I did
      > > the "dishwasher test" with no change to the stock.
      > >
      > > I also left an approx. 3 x 3-foot piece out in a Northern New England
      > > winter -- that's about 5 months of snow, sleet and freezing temps. The
      > > piece of ply was propped up a few feet away from the exhaust outlet
      > > from our propane-powered boiler, which means it was blasted on one
      > > side with hot, moist air several times each day. The piece of ply
      > > survived this just fine - no delamination or checking.
      > >
      > > I think UltraPly is made in the U.S., which may mean it is
      > > manufactured under stricter controls than imported materials.
      > >
      > > I took the boat on a 4-day "cruise" earlier this summer and was
      > > subjected to some pretty rough poundings. I road out some pretty
      > > violent thunderstorms while at anchor, sailed up onto the beach
      > > several times and had a three hour downwind sleigh ride surfing down 3
      > > - 4 foot waves (My gps clocked consistent speeds of 6.5 mph, with the
      > > highest speed zI saw at 7.1 mph -- even if you figure the incoming
      > > tide was helping me along over the ground, that's pretty good speed
      > > for a 14 foot waterline and a homemade/sewn PolyTarp balanced lug
      > > sail). During all of this, the boat felt solid as a rock, and I never
      > > heard a crack or creak.
      > >
      > > IMO, saving $200 on a project this size is worth it. That paid for ALL
      > > of my epoxy supplies. I see no reason why, with proper protection in
      > > the winter and normal spring maintenance required of any wooden boat,
      > > it should last as long as a boat made out of $70/sheet marine ply.
      > >
      > > You can check out a rather large Web site about the building of my
      > > boat (including pictures and more thoughts on using UltraPly) at:
      > http://www.davidcmaguire.com/AF3
      > >
      > > David C.
      > >
      > >
      > > On Aug 31, 2009, at 1:20 PM, recree8 wrote:
      > >
      > > > I think there is a lot of interest on the various types of
      > > > underlayment plywoods that are coming from "Offshore" and carried at
      > > > most big box suppliers. Sureply was one mentioned and there are
      > > > other brands as well - Ultraply is another.
      > > >
      > > > I recently purchased some 1/4" stuff that was actually called
      > > > "merranti" and has no nailing grids on it. Looks really nice. It is
      > > > 3-ply with a darker, thicker middle core and two thinner ones on the
      > > > exterior which are beautifully smooth and knot free with no visible
      > > > voids anywhere.
      > > >
      > > > I cut some narrow strips off a sheet and did the "dishwasher test" -
      > > > leaving them in the dishwasher for several long cycle wash loads.
      > > > Then left them to dry out. In some spots I could peel off the outer
      > > > layer just using my thumb nail, and there appeared to be no sign of
      > > > glue at these locations.
      > > >
      > > > What appears to have happened is it had some glue-starved spots in
      > > > it. Perhaps the inner core, being more absorbent soaked up most of
      > > > the glue during the manufacturing process and left the joint starved
      > > > of glue.
      > > >
      > > > Not saying it would not work if one is encapsulating the wood with
      > > > epoxy and glassing the exterior,thus keeping moisture out, but I
      > > > also am a bit leery that if you have uneven heat applied to the
      > > > hull, say when storing the hull outside upside down under a hot sun
      > > > and even covered with a tarp with cooler moist air underneath, you
      > > > might get some ply separation inside the plywood.
      > > >
      > > > Is it worth the cost saving with a boat hull if using this plywood
      > > > at $20 a sheet compared to real merranti at $60 a sheet? On a 5
      > > > sheet boat it means a saving of $200.When you consider the total
      > > > cost of the boat, including the epoxy, cloth, paint, varnish, spars,
      > > > and framing, and sail I would suggest it is a risk unless you are
      > > > either practicing with your first boat or only intending it to last
      > > > maybe 5 years of occasional use compared to 10+ years of hard use.
      > > >
      > > > The difference in my view is the lack of quality control from the
      > > > "offshore" stuff - if lucky you may have no problems, but the
      > > > quality control of USA, European and Canadian made stuff, is much
      > > > more consistent.
      > > >
      > > > From my understanding underpayment is intended to provide a smooth
      > > > surface to lay carpet over and it is nailed down every foot or so or
      > > > even less, so s bit of separation of ply's under the carpet may
      > > > never be noticed. If it happens on your hull bottom it is a very
      > > > large source of concern and potential head scratching on what to do
      > > > to correct the separation from extending over time. Not that easy to
      > > > repair either.
      > > >
      > > > Any other thoughts on this? Have some people done testing with their
      > > > particular brand and found it to be free from separations? If so let
      > > > us know.
      > > >
      > > > Nels
      > > >
      > > >
      > >
      >
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