It seems every winter, within 25 miles of Annapolis some unfortunate soul slips off an icy dock or deck while doing the obligatory boat check - and dies of hypothermia or cardiac arrest. You would be surprised how slippery a snowy dock or deck can be.
A dock mate leaves his boat in the water most years, last winter (2014) his fuel line split where water had accumulated, filling his bilge with diesel. Luckily his bilge pump discharge froze solid before the boat could discharge the fuel overboard, but the resulting split bilge hose managed to spritz his interior with diesel.
In 2010 I left my boat in the water until January, the resulting ice that locked the hull and then ground against it managed to do $1,500 in damage to my boot stripe.
Check your insurance, most require no navigation during winter layup - or you can pay extra.
My rule: Nothing good can happen to a boat left in the water through the winter.
My thoughts...
1. I go ice climbing for fun. Why would I fall? And yes, good sense is required. However, if the boat is well prepared there is no more reason to check on a boat while there is ice on the dock than there is to check on a boat during a hurricane. Snow just doesn't last that long around here.
2. I've experienced serious damage from improper blocking. I think the risk is perhaps equal. Since the insurance company does not NOT charge more for the winter afloat (my policy is clear on this), I'm guessing they've done the math. I've seen a lot of damage on hauled boats caused by ice, covers that got loose, snow load, water freezing in bilge, split rudders (water froze--can't happen in the water), and boats blown off stands. In other words, a wash.
3. $1500 for a bootstripe? Was the gelcoat damaged, or do they just charge a lot for paint? However, if my marina were subject to moving ice, I agree, get out of there! I've frozen in a few times, but there is zero movement where I am. Additionally, being brackis, the ice is mushy; just a few miles north that changes. And yes, being dependent on electricity to run a bubbler is not a robust plan.
4. Sailing can happen. Wonderful, quiet, sailing. A cozy evening with the wife.
My insurance does require a 2-week layup, during which I cannot sail, which falls just before Christmas. Busy then anyway.