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Well that's cheered me up
My boat's on the hard at Arzal. Tanks are emptied but......did you leave the taps open? Pipework has survived a colder spell but the boat was afloat in fresh water.
Air temperature needed to considere water tanks to freeze
- Thread starter psousa
- Start date
Well that's cheered me up
My boat's on the hard at Arzal. Tanks are emptied but......did you leave the taps open? Pipework has survived a colder spell but the boat was afloat in fresh water.knuterikt
Well-Known Member
Can you explain why I have had frozen water in my bilge some winters in Norway. Ice in the fjord i frozen (safe to walk on) boat in water with bubbles to keep ice from forming around the boat. This happens happens when we are having longer periods with night temperatures bellow -10 and mid day somewhat above -10.
LittleSister
Well-Known Member
I've got a max/min thermometer on the boat, which I noticed recently showed the temperature in the cabin had been down to -1.8 C earlier this winter (though I don't know when - and was probably not as cold external air temp as it is now).
I try to leave the tanks empty this time of year. Although, like Antarctic Pilot's, one side of my water tank is the hull, which will mean it'll be near the temp of the water the boat is floating in, if it were to freeze up the potential damage could be serious, and much more of a faff to repair than just replacing the odd tap, pipe or whatever.
When draining the tank I let it pump air, but it's impossible to get every bit of water out without dismantling the system. I haven't had a problem so far.
I try to leave the tanks empty this time of year. Although, like Antarctic Pilot's, one side of my water tank is the hull, which will mean it'll be near the temp of the water the boat is floating in, if it were to freeze up the potential damage could be serious, and much more of a faff to repair than just replacing the odd tap, pipe or whatever.
When draining the tank I let it pump air, but it's impossible to get every bit of water out without dismantling the system. I haven't had a problem so far.
AntarcticPilot
Well-Known Member
Is the water in your bilges fresher than the surrounding seawater? That would explain it freezing despite the boat remaining afloat. It is clear that the surrounding water is at the freezing point of the seawater, but being salt this is a degree or two colder than the freezing point of fresh water. So any contribution to your bilge-water from condensation or precipitation would make it fresher than the sea water, and hence more likely to freeze. This is unlikely to happen in UK waters where seawater rarely freezes; if it does freeze it tends to be because a fresh water input is floating on top of the seawater, with the bulk of the water remaining
Ice safe to walk on need not be all that thick; ice is surprisingly strong. ISTR (and it's a while since I read up on it) that ice a foot thick can take an aircraft landing on it! In fact, I just looked it up, and the formula for old sea ice is that the thickness in inches for sea ice is (27/4) times the square root of the weight of the aircraft in tons! So, 12 inches of ice will allow an aircraft weighing over 3 tons to land on it. Obviously, an aircraft landing exerts a much higher shock load than a person walking on the ice! Lake ice is almost twice as strong.
lw395
Well-Known Member
If it's below zero for extended periods, why would you not expect fresh water to freeze?
Also those air bubbles? are we talking about pumping air under the boats to prevent solid ice forming? As the bubbles expand, they cool- adiabatic cooling, the reverse of a bicycle pump getting hot as you pressurise the air. As the dry air evaporates a little water, that cools the remaining water/the hull.
At minus ten outside, your hull say it's a couple of degrees inside, will lose heat very quickly, compared to say where I am now, -3 outside. Here in the UK it will take longer for a boat's tanks or plumbing to freeze, but it will happen if it stays below zero for long periods, unless your boat is getting some warmth from the sun or a heater.
Ironically, having a lot of water in your tank gives it a lot of heat capacity, so it takes longer to freeze. A few litres in a pipe has little heat capacity so may freeze quickly.
It's beeen below zero here for 24 hours, the water butt is slowly freezing. It will take a long time to freeze the whole thing, no doubt tomorrow's strong wind will speed the process.
My mate put the eberspacher on today, starting tonight with the cabin at 20 degrees, it will take longer to get down near freezing. But the freshwater plumbing to sinks and shower was drained the other week. We use the wet vac to suck through the pipes. Cleans the vac out after doing the bilge if nothing else.
Momac
Well-Known Member
It's not all that surprising to foresee freezing temperatures in the winter in Europe - is it?
In the UK there have been mild winters for several years . Some of the people in my office who are under 30 are just now driving on icy roads for the first time. I advised one of them today (who commented on drivers this morning going at 20mph down a hill) - if there is ice on the footpath there may be ice on the road - even if the tarmac looks black.
I dare say there are a few boaters who are of insufficient age to have the experience of a proper cold snap and will be caught out by not having taken any precautions against frost damage.
By Sunday Lunchtime the cold snap will probably be a distant memory - I genuinely hope no one reading this finds any frost damage to their boat.
lpdsn
Well-Known Member
The bubbles are likely to be bringing warmer water up to the surface with them. AIUI, water is strange it that it expands when cooled below 4 deg C so colder water at the surface will freeze rather than sink leaving warmer water below.
Chris_Robb
Well-Known Member
Well that's cheered me up
And the pressure tank and pump were buggered! Sorry ---- I was as when we went into the water and switched on the pressure pump - nothing happened - changed the pump for a spare and hissing noises - fixed the first one - all ok - then the next bit burst then the next ......
edit: I did have heating on board - paid for a dedicated power line - some other bugger had pinched it!
I hope you are ok....
knuterikt
Well-Known Member
Your arguments is biting itself in the tail, (and when did we restrict this to UK waters?)
My bilge is cold enough for sea water to freeze, with temperature inside at -6 and below for several days and cold air sinking if would not be surprised if the temperature in bilge was lower. When i checked last time it had formed a 1 cm thick ice layer on top, so the water is freezing outside in. the heat from surrounding water is not enough to prevent that from happening.
A water tank would be even more exposed since the cold air would expose all sides of the tank not only the top.
Water in tank will freeze outside in and when the process first starts it goes fast.
A well know trick to make ice light is to fill a bucket with water an leave it out in the cold overnight, if you are lucky you will have an ice shell filled with water. make a small hole and drain water, put a candle inside..'
I do winterize both toilets, engine and freshwater system even though we keep the boat in water during winter.
If anyone is questioning the forces of freezing water just have look at this picture, a half filled tin with fresh water left outside in -12C overnight, you can see that the bottom is deformed.
knuterikt
Well-Known Member
I know well that the bilge water will freeze, it's was the theory that liquid water on the outside would make a water tank immune to freezing i qustioned.
psousa
Well-Known Member
Well... In spite of all your contribution, which I appreciate a lot, I want to believe that negative temperatures (with the minimum reaching -5, as far as I can remember) outside for 12-14 hours doesn't make the boat to be 0º or less inside... Glassfiber should offer some temperature resistance (I hope!)
lpdsn
Well-Known Member
Snow on deck should help with the insulation too.
[3889]
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Oh well - fear the worst, hope for the best. Thanks for info, all will be revealed in a fortnight.
davethedog
Well-Known Member
Mine has been left in the water in Portsmouth and was left with 3/4 tank in one water tank and the other was almost empty.....fingers crossed when I get to her (hopefully Sunday). Forgot to open the taps though!!
tjanderson
New Member
I have never had a boat freeze up when it is afloat. Ashore yes. On the South Coast the water rarely seems to go below about 5 degrees C so the boat is sitting in water well above freezing. The decks and windows might frost over but piping shouldn't freeze. Take it out of the water and the cold wind blowing all over the hull will quickly freeze it solid.
psousa
Well-Known Member
Just an update:
I was at my boat last weekend and no issues. The pump remained switched on and I heard no unexpected starts.
Marina station registered -7 degrees one day, during that week. The boat was afloat. The tanks were no full but with water. The taps were closed and I didn't drained any pipes.
I left the boat yesterday again but I've left the taps open this time. Both tanks are almost full (as far as I understand from this post, the water works also as a heat retainer).
Thank you all for your tips!
I was at my boat last weekend and no issues. The pump remained switched on and I heard no unexpected starts.
Marina station registered -7 degrees one day, during that week. The boat was afloat. The tanks were no full but with water. The taps were closed and I didn't drained any pipes.
I left the boat yesterday again but I've left the taps open this time. Both tanks are almost full (as far as I understand from this post, the water works also as a heat retainer).
Thank you all for your tips!
[70521]
Well-Known Member
Depends on the amount of insulation between the cold air and the water in the tanks. If can be Zero degrees kelvin and you can still have liquid water if the insulation is good enough.
jac
Well-Known Member
Pleased to hear the good news!
alant
Well-Known Member
Difficult to get all of it out.
cpedw
Well-Known Member
That's got to be some exceptionally good insulation.