Also a low volt battery (from sitting) has a good chance of freezing
and busting. thus electrolite drained all inside the boat, that is
unless you're battery is encased in a battery box, and that's still no
garentee.

PLUS a battery will normally loose 3-4% of it's rating per month due to
natural deterioration, and by letting it sit idle in low temperatures,
will cause it to deteriorate at a quicker rate.

Yes, if you are going to store your boat for the winter, I'd suggest
taking the battery completely out and storing it inside if possible.

My friend lives in an appt. complex and cannot do such, so, he goes to
an extreme. he switches the battery in his pick up truck and boat
battery every couple weeks in the winter.

Yeah, like I said thats an extreme, but he doesn't seem to have much of
a problem with batteries being consistantly charged.