How big is the dock building industry?  I already know how many
commercial marinas there are, but how many residential docks/boat
slips are there in the U.S., and how many get constructed each year?

Hello, Jonnyringo-ga:

I've been in touch with the Deck Industry Association, which
represents the builders of residential decks and docks, as well as
their supporting industries.  Unfortunately, they do not track any
such statistics, and do not know of anyone doing so at present.  They
did say that it seemed like an idea they should consider, however!

I will be pursuing a few other avenues over the next week, but I don't
know if the information is out there to be found.  Either way, I
wanted to let you know that your question has not been ignored!

-Chromedome

You said you'd be pursuing other avenues this week.  What information
have you found?  Let's touch base as soon as you can.  Thank you.