spacer between Pontoon rails and deck
 

I'm completely restoring an old 28' JC Pontoon. I've noticed most new
pontoon boats have 1/8 - 1/4 inch "spacers" between the aluminum rails
and the deck. Looks like this is done to let water freely flow off
the deck. Does anyone know what these are called, where I can find
them, or what a good substitute would be. Also, if someone wants to
talk me out of it, that would be OK.