Quick aside: Speaking of towing, I don't know but I've been told...

With Boat US tow insurance, coverage travels with the PERSON, not the vessel. So, if you have coverage and are on someone else's boat in need of a tow, your insurance coverage still applies. Can be worth a lot of scratch.

I never knew that, but apparently it's the case (or was, as recently as about a year ago).

So, regardless of whether you bring a boat, it's good to bring your card.