Two interesting things about registering my N20 in FL.
1) I couldn't get insurance for it unless it was registered.
2) Shortly (ok, 6 months or so) after I moved here, I got a letter from the county Tax Collector stating that I had an "unregistered boat" parked in my driveway. It came along with a sternly worded mention of fines and penalties if I didn't register the boat within 30 days.
