Similar law exists in RI (16 feet = need to register). Lots of people assume that if it doesn't have a motor, it doesn't need to be registered. Not correct. Worse thing is, it's not a DMV item in RI, so you have to hunt for the right resource (easier now with internet of course).

I registered my second Hobie Cat, and was the only one at any event that had (from RI anyway). Never bothered again, and 3 H16s later, never had an issue.

Mike