Air temperature needed to considere water tanks to freeze

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psousa

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Seems to be a dumb question but I'm from a place where temperatures rarely drop below +10ºC close the coast lines. Now I have a boat which is laying in Atlantic coast of France. I have been controlling the marina weather station and these days the temperature lowered to -4ºC and later at night they are expecting -5ºC. Is this enough to freeze the water int the tanks?
Before I left and because I felt a cold which I'm not used to, I ask my neighbor if I should be concerned about tanks contents freezing on this part of the globe but he told me they have no such a problem. Now they have an unexpected weather caused by an arctic air flow.
As far as I know -5ºC is not enough to make water in the tanks to freeze but I have no experience on this.
I appreciate answers from people used to deal with this.

Thank you
 
Depends if the sea freezes. The sea temp is unlikely to be below 4 degrees. So the inside of the boat should stay above freezing. My experience in Norway suggests that you may get some icing on the windows nut the tanks will be ok as long as the sea stays liquid. As soon a the sea freezes so will everything else.
 
Yesterday afternoon it was -6ºC in my boat. at the time air temperature was -8ºC outside. Morning temp same morning was -14ºC.
If this last for some more days the water in my bilge will soon freeze, any water left in tanks or FW system will freeze before that.
 
In my experience the items most vulnerable to frost are fresh water pipes and especially pumps. Damage may occur there long before the water tank freezes.
 
BabaYaga said:
In my experience the items most vulnerable to frost are fresh water pipes and especially pumps. Damage may occur there long before the water tank freezes.
Click to expand...

I agree. Taps are especially vulnerable too. We once had taps freeze solid, while the water in the tanks was OK, lucky the plastic taps survived.
 
The tank hopefully has a larger volume of water in than the pipes / taps.
Thus there is more residual heat in the tank and it will take longer to freeze than the pipes / tap.

Small amount of fresh water in my bilge today is still liquid, still frost and snow on the deck, -4C overnight, boat is ashore.
 
BabaYaga said:
In my experience the items most vulnerable to frost are fresh water pipes and especially pumps. Damage may occur there long before the water tank freezes.
Click to expand...
I always drain my water tank when laying up in the northern Adriatic. But arriving after a particularly cold winter in NE Italy during when the lagoon harbour's brackish water had frozen over, I found the galley whale foot-pump split from the dregs left in it.

I now ensure I am sucking air through the entire system, including all pumps, before leaving for the winter.
 
I think it is the length of time that the temperature is below zero as much as the temperature itself.

Think of the tank full of water as a reservoir of heat,. The lower the temperature it faster it leaks out. But if it is below zero for a prolonged time it will eventually all leak away and the water will freeze..
 
I have the domestic water drained off my boat and frost protection heaters in place. It seems to me winters on the continent are potentially just a cold if not colder than here in the UK.
The water inside the domestic system is not salty so freezes before the sea.
 
As others have said, a boat that is afloat is relatively immune to the water in the tank freezing - if the water the boat is floating in is still liquid, then it is unlikely that the water in the tank (which is most likely adjacent to the underwater hull; in mine one side of the tank IS the hull) will freeze. It is theoretically possible, as sea-water freezes somewhat below zero, while fresh-water freezes at zero, but in UK waters it is very unlikely; the difference is only 1 or 2 degrees. However, as others have said, the water in the pipes can and does freeze; I've had this happen and fortunately, the pipe joints at the taps gave way without damage. Found the leaks when I filled the tank and realized a) that the pump was running continuously and b) the blilge had fresh-water in it! Since then I've always drained the system before leaving her for the winter, even if she's staying afloat.
 
Thank you all.
Nice discussion. I wasn't expect.
I understand the damages and, as matter of fact, I've already read about it many times. That's why I've asked my neighbor before I left. Which I don't know is which temperatures we need outside to make water to freeze inside the boat (tanks and pipes) because here, I guess, experience counts, and I have no experience of having a boat on a cold place, as I told you.

Since yesterday 10pm, the weather station is registering <0 degrees. -5 at 7am today. -1 right now.
The salty water is still shaking (they also have a live webcam). It's windy and the marina is located at a river mouth.
According to weather forecast, it will keep <+1 until tomorrow morning.

Considering the information, I can expect NO frozen water in the tanks BUT frozen water in the pipes. Is this correct?

Thank you.
 
Poster on the Thames forum did little experiment.
Two temperature gizmos which logged temperature at time intervals set by the user were placed in the bilge, and main cabin of a 25ft glassfibre boat.
The record of temperatures could be uploaded via USB a tablet or laptop, in the form of a graph.
The boat was located in a freshwater marina with virtually no flow.
The info collected was during a very cold spell in a midwinter week.
Ice did form on the water surface of the marina and was estimated at being several mm thick.
During the period recorded the temperature record in the bilge remained around 5 or 6 C.


http://www.ybw.com/forums/showthread.php?307782-Winter-Temperatures&highlight=
 
Last edited:
oldgit said:
Poster on the Thames forum did little experiment.
Two temperature gizmos which logged temperature at time intervals set by the user where placed in the bilge, and main cabin of a 25ft glassfibre boat.
The record of temperatures could be uploaded via USB to your tablet or laptop.
The boat was located in a freshwater marina with virtually no flow.
The info collected was during a very cold spell in a midwinter week.
Ice did form on the surface of the marina and was estimated at being around 20mm thick.
During the period recorded the temperature record in the bilge remained around 5 or 6 C.
Click to expand...
That ties in with my experience - the pipe joints that gave way were all above the water line, suggesting that pipes int he bilge and low down in the hull didn't freeze.
 
psousa said:
Thank you all.
Nice discussion. I wasn't expect.
I understand the damages and, as matter of fact, I've already read about it many times. That's why I've asked my neighbor before I left. Which I don't know is which temperatures we need outside to make water to freeze inside the boat (tanks and pipes) because here, I guess, experience counts, and I have no experience of having a boat on a cold place, as I told you.

Since yesterday 10pm, the weather station is registering <0 degrees. -5 at 7am today. -1 right now.
The salty water is still shaking (they also have a live webcam). It's windy and the marina is located at a river mouth.
According to weather forecast, it will keep <+1 until tomorrow morning.

Considering the information, I can expect NO frozen water in the tanks BUT frozen water in the pipes. Is this correct?

Thank you.
Click to expand...

I would expect no frozen water even in the pipes - remember that the weather station will take the air temperature - the internal boat temperature will be somewhere between the air temperature and the water temperature.

That said - there is a risk of some frost damage in pipes, especially if taps etc are closed so there is really no room for expansion and the water is under pressure . Personally I wouldn't worry too much but when you are next down there ( and I wouldn't delay the visit) I would personally inspect the fresh water system very carefully, paying close attention to joints, pumps, narrow pipe runs and taps / valves. Don't be surprised if something is damaged but I wouldn't expect it.
 
psousa said:
Seems to be a dumb question but I'm from a place where temperatures rarely drop below +10ºC close the coast lines. Now I have a boat which is laying in Atlantic coast of France. I have been controlling the marina weather station and these days the temperature lowered to -4ºC and later at night they are expecting -5ºC. Is this enough to freeze the water int the tanks?
Before I left and because I felt a cold which I'm not used to, I ask my neighbor if I should be concerned about tanks contents freezing on this part of the globe but he told me they have no such a problem. Now they have an unexpected weather caused by an arctic air flow.
As far as I know -5ºC is not enough to make water in the tanks to freeze but I have no experience on this.
I appreciate answers from people used to deal with this.

Thank you
Click to expand...
in 2001 I had a boat in Le Roche Bernard on land. I went down their in Feb to do some work - the boat was glistening in Ice and although I had emptied the tanks and the calorifier, there was sitll residual water in the pipes.

Come Launching in spring, I found almost every pipe burst.

The Atlantic coast of France can be a damn site colder than the south of England.
 
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