I apologize if this question either has an obvious answer or is
addressed elsewhere, but -- what boat characteristics, including size
and type, self-bailing cockpit, open dinghy vs. small cruiser, keel
vs. centerboard, and so on, permit safely leaving a small boat
permanently in the water, either at a mooring or at a dock, given a
temperate climate and no freezing?

"Small boat" here means one of 15-21ft or so, and may signify as well
an easily trailerable boat, including dinghies. Also included are
those with heavy keels, such as the H12 1/2s, which might be difficult
to trailer. Excluded are Sunfish, Lasers, and boats similar to those
in that they can be easily hand-carried or car-topped to water.
Excluded also are times of hurricanes, but not less catastrophic
weather, although if the expected local weather is a critical factor
that would of course be helpful to know.

Thanks!

Wayne