Tom G wrote:
I'm replacing the carpeting and a couple of rotted deck boards on my pontoon
boat. Marine plywood is pretty much hard to get around here but I can get
MDO plywood (Medium Density Overlay) which has a resin impregnated (Paper?)
layer on each side. This stuff works great for outdoor signs, etc and lasts
virtually forever. However the carpet guy is telling me that the carpet
adhesive won't work with it because "nothing sticks to it". I've queried
the mfg of the adhesive and they don't seem to have a good idea of what MDO
is either. The carpet guy even tried to tell me that paint wouldn't stick
to it. Years ago I had a commercial outdoor sign painted using it and it
lasted for years with no noticeable weathering or paint loss. So, has any
one had experience using it and applying carpet or glue to it. The Exterior
plywood I've found is really bad quality.

Tom G.

I know that Norm from This Old House and New Yankee Workshop loves the
stuff because of it's ability to stay together better than plywood in a
damp environment. He paints it all the time without trouble.

From Bob Vila's website:
Called MDO, or medium density overlay, it's engineered plywood with a
resin treated fiber applied to both faces. This gives an extremely
smooth finish that is easy to paint. In addition it's rated for
exterior use, which means it is safe from the elements, insects, or
other outdoor hazards, making it a perfect choice for the new deck or
porch.

I'd say use it!