Mike,
If you read reports from organizations like BOAT-US, the majority of claims they have for freezing come from the "middle" states. Everyone up north winterizes their boats. Owners way down south don't need to. The ones in the middle don't think they need to, but when it gets cold (as it has been recently), all sorts of bad things happen. Most people I know who keep their boat in the water all year, if there is ANY chance of freezing, will winterize it. When a storm or cold front comes, there is a decent chance that there will be a power outage, which make electric heaters worthless. A few bucks a gallon for anitfreeze is a lot less expensive than a new engine or new plumbing. Just my $0.02.

Check to see if your heat exchanger bulged. Even if it did, it might not be damaged, but something to watch for when you start up in the spring. Take a look at your raw water pump housing and make sure it did not bulge or crack as it's cast bronze. Again, when your first start up, check to make sure raw water is pumping out the exhaust. The third major area to check is your water heater and fresh water pump once you pressurize your system. If you had a hard freeze, you might have other surprises come spring - shower wand, foot pump, faucets, etc, but these are minor. Suggest you winterize as much as you can right now because the coldest month is yet to come!

I've learned from this season that the regular pink antifreeze is not cutting it up north of Boston…had to throw rock salt in the bilge, and melted and drained (with a hair dryer) the ice in heat exchanger and raw water intake strainer. I think the rain water draining from the mast diluted the bilge antifreeze and there was possibly some dilution with the raw water system when I winterized it in the fall. There's a newer higher freeze point pink antifreeze on the market (-50 below?) that I will use next year. Tough winter

[QUOTE=pkeyser;20991]I've learned from this season that the regular pink antifreeze is not cutting it up north of Boston…had to throw rock salt in the bilge, and melted and drained (with a hair dryer) the ice in heat exchanger and raw water intake strainer. I think the rain water draining from the mast diluted the bilge antifreeze and there was possibly some dilution with the raw water system when I winterized it in the fall. There's a newer higher freeze point pink antifreeze on the market (-50 below?) that I will use next year. Tough winter[/QUOTE]
The antifreeze won't cut it for the bilge, for the simple reason that it apparently is heavier than water and thus a mixture that accumulates in the bilge separates out. I imagine this problem would not be cued using the -50 antifreeze.
I used to dump antifreeze in the bilge the first year or two, only to end up having to break up the crust of ice that formed on top. So, rather than simply throw money away on antifreeze (which just ends up raising the level of the water / ice accumulation), I've found the better thing to do is make sure to sponge out the bilge every few weeks. I disconnect the power from the bilge pumps, and swung them up out of the bottom to avoid ice damage.
In one of his articles MaineSail recommends taking care to make sure that one has really pumped enough antifreeze through the raw water system to minimize any dilution issues; if the pink stuff hasn't actually displaced all the water, the results might not be pretty.

Haven't suffered a frozen boat but have dealt with several frozen houses. I assume it's similar. First thing is let it thaw slowly. Rapid temperature changes will cause damage. Second is check everything that has water in it or on it. Follow the plumbing, look for water follow the leak to its source, cut off water to it while you fix it then flow water again looking for the next leak. Eventually you get them all. I would be very carefull with thru hulls. Good luck. You'll probably be chasing leaks for a while