On my way down to florida, in the washington area if my memory serves me right, i was on I-95 and saw a little kind of bay with not only one, but many boats in their slips, in the water, but it was actually frozen. Not only frozen since an hour or 2, im sure it was frozen like you could never think about getting out of water because they are stuck there in probably 2 to 6 inches of ice.

Is this a normal thing happening in some places that it sometimes ices but not for long?

Im sure there is nothing good for a boat to be stuck in there...

Anyone can explain me this?

Virginia doesn't get frozen water the way you think of it. Provably a once in 10-20 years that that place freezes and normally it probably only lasts a couple days. Normally it never freezes even lightly in my canal but this year we have had several freezes

And do you guys do with the boat? Winterize and leave it in the water?

Lot of marinas use bubbler systems around here.

i have heard of boats that have heaters on the docks around the boat to keep the water from freezing. never seen it

Maybe not so surprising there's so many boats available for part out back there.