On ice and time lags

How low does the outside temperature have to get before things freeze inside the boat?

A lovely sunny day, but down here on the Slough arm the ice is really thick. I broke this piece off from near the stern of the boat this morning. Further away I think it might be thicker.

Inside the engine bay the temperature last night fell to about +4 degrees so that’s OK. I’m not sure what the outside temperature was. Halfie suggested that by measuring outside and inside temperatures we might be able to predict future risks if interior freezing from the weather forecast. Thinking about it, that wouldn’t really work because the variable factor is how long the cold temperatures have held for. In a prolonged freeze up, and unheated boat will gradually lose temperature, at a rate dependent on its insulation, until eventually it would be as cold inside as out. Of course temperatures rise and fall throughout the day, and sunshine on a boat can pump quite a bit of heat into the shell and through the windows.

According to the Met Office, it should fall to about -5 degrees here tomorrow (Saturday) night, then much milder weather should set in. I wonder how long the canal ice will take to melt next week.

I really need to work out a policy of when to come out and warm up the boat during prolonged deep freezes, or to go to the trouble of completely draining down all the vulnerable pipes and pumps - not easy.