Planning for spring. I will rebed my stanchion bases. Under the deck,
the backing is a thin piece of fiberglass. I would like to give the bases
a bit more support. I came across the material Starboard.

For myself, I would have gone with marine ply, but the idea of using a
plastic cutting board is simple, cheap and brilliant. I can definitely see
myself using it in future!

If you decide to go with stainless, get it cut for you (try to find a shop
with a guillotine, thats the quickest way to cut it and they probably wont
charge). You'll need a good supply of quality drill bits; think cobalt, not
the $20 for 100 bits kit.

If you go with aluminum, it neednt be one of the 5000 grade varieties....
while this is what we use at work for building boats, i wouldnt class the
underside of a deck as being a marine environment. You could get away with
pretty much any old garden variety of aluminum here. You can cut it with
any tool that you would use for wood working that has a carbide tip blade
(sawzall, circular saw, table saw etc) it even hacksaws pretty easy.
drilling is a breeze.

regardless of what you choose, re-bed the stanchion above deck with a
quality bedding compound (3M is pretty good) not with liquid nails, epoxy or
whatever else you have in your tool box. *Do not* use bedding compound under
the deck! If you have water getting through from the top of the deck, you
want to know about it. If you seal the bottom as well, the water has
nowhere to travel except internally along your fibreglass or ply deck. by
the time you find out about it you will be in big trouble. For the same
reason, I would not fibreglass the underside of the deck.

Shaun