Brettski,
Composite decking is actually not a good choice for docks. They dont last nearly as long as advertised and start fading instantly. They absolutely can not touch the water at all. Composite decking looks awesome on docks for about 1 year, then it looks horrible after that.
We use plastic deckboards for docks. They are made out of 100% recycled milk jugs and will last forever, even if submerged in water. They will never rot, swell, or fade. There are some tricks to learn with plastic though. A 16' plastic deckboard will shrink and expand long ways up to 3/4 of an inch between summer and winter. Must plan accordingly.
