Winterising a boat afloat

[[3889]]

I winter afloat in fresh water in Brittany. I drain calorifier, water tanks and raw water engine jacket but don't use antifreeze. March 2014 had sub zero temps for 2 weeks and all was well.
@VyvCox, am I right in thinking you left fresh water in your Yanmar heat exchanger in freezing conditions without ill-effects?

Edit: cross posting, ignore last paragraph.

 

[[70521]]

I used to winter my previous boat in the Caledonian Canal. One winter there was a cold spell, and a large old fishing boat being converted, sank, because a cooling hose attached to an open seacock froze. The frozen hose pulled off the stem on the seacock, presumably because of the expansion, so when it thawed again, water poured in and the boat sank. Another boat close by, had similar damage but was spotted before she sank.

The canal is fresh water.

While I've seen the canal frozen over I've never seen much sea ice in the loch.

 

[knuterikt]

This oil cooler has been damaged by freezing, I will not risk damage to my engine just to save some anti freeze and work..

Thread in Norwegian here http://baatplassen.no/i/topic/125637-vp-d4-varmeveksler-lekkasje-ved-oljekjøler/

 

[NormanS]

The canal is fresh water.

While I've seen the canal frozen over I've never seen much sea ice in the loch.

I am well aware that the Caley Canal is fresh water.
I was responding to #2.

 

[Polly's Kettle]

OK, I'm going to admit that my winterisation has historically been pretty much zero. I've never drained the calorifier, and often leave half a tank of fresh water - one weekend I walk away, and 4 months later I realise that was my last weekend of the year. To be fair, I do get the sails off!

So my question is - in practice, how does one drain a calorifier? If anyone recommends antifreezing it (glycol??), how do you actually do that?