Ice Diving Water Temps

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DOkie

Guest
Messages
263
Reaction score
2
Location
Menominee, MI
# of dives
500 - 999
I need help here. On the Basic Scuba Board, there is a question regarding cold water temperatures. The gentleman that started the thread stated that he recorded fresh water in liquid form at 30 degrees (f). I have been on ice dives where the temps range from 28-31 degrees (f). Everyone else is saying this is impossible because fresh water freezes at 32 degrees. They are saying that the bottom temps (summer or winter NEVER get below 39 degrees. Personally I've dove the Walter B. Allen in the middle of July with a bottom temp of 35 degrees. According to the US Dept of energy, fresh water can still be in liquid form below 32 degrees. Only PURE water freezes at 32 degrees. (Water created in a lab).

What is the coldest temp you've ever recorded? (Summer or winter) Thanks!!!
 
I need help here. On the Basic Scuba Board, there is a question regarding cold water temperatures. The gentleman that started the thread stated that he recorded fresh water in liquid form at 30 degrees (f). I have been on ice dives where the temps range from 28-31 degrees (f). Everyone else is saying this is impossible because fresh water freezes at 32 degrees. They are saying that the bottom temps (summer or winter NEVER get below 39 degrees. Personally I've dove the Walter B. Allen in the middle of July with a bottom temp of 35 degrees. According to the US Dept of energy, fresh water can still be in liquid form below 32 degrees. Only PURE water freezes at 32 degrees. (Water created in a lab).

What is the coldest temp you've ever recorded? (Summer or winter) Thanks!!!

36*F, on a thermometer I trust (it was anchored on the bottom).

Keep in mind, most thermometers are good to about +/- 2*F, 1*C.

Also, it can take 5 minutes for the temp in the guages and your computter to equalize with the water around you.

Bottomline, don't take your temps as gospel.


Ken
 
Fresh water (with little chemical influence) will freeze very close to 32°F (when the water is still)

Moving water can't freeze if there is enough "dynamic" flux to keep it from freezing. Add in upwelling and you can have water below freezing and thus in a liquid form.
 
DOkie,

Don't let that guy from the other thread bug you - he was just a "jerk" by anybody's definition. I had a whole term of Thermodynamics in college and I assure you I can't remember exactly at what temp freshwater is the densest or the variance due to pressure. If I can find my book I'll try to look it up.

If your computer showed a temp lower than 35 might it still have been showing the surface temperature? We got discussing temp readings at the quarry one day. Apparently, even computers that cost a lot more than mine take forever to show an accurate temperature.
 
Can't find my Thermo book but found my old log book that showed 36 deg at 75 ft in Grand Traverse Bay in mid June. I remember that dive because I promised myself never to do that again - unless I get a drysuit someday.
 
Personally I've dove the Walter B. Allen in the middle of July with a bottom temp of 35 degrees.

35F = 1,7C. Rounded up it's 2,0C, which means your gauge only had to be 2C off to show what you got IF water temperature was 4C. -Which to me seems fairly likely. I've seen computers more off than that several times.


Sincerely,

Retro's "jerk"


PS! I am really sorry to have offended you, as I apparently have. It's just so obvious to me that water is at it's densest at 4C/39F and that ordinary freshwater in a lake for all practical (scuba related) reasons will freeze at 0C/32F, and I have yet to meet a scuba diver who questions this.



EDIT:
Walter B. Allen on Youtube: YouTube - Walter B. Allen Shipwreck

Holy crap! This one's on my list of to do things!
 
ok. Since we're being civil (and since you caught me :D ) sorry I called you a jerk.

If we want to exercise our brains lets think about this : If the water on the bottom is 39 deg and there's ice on the top at 32 deg. What's in between? That is, where is the water 40 deg ? And where is it 38 deg ? An interesting question might be what is the warmest water you've read under the ice? I'm not sure that it's 39 F.
 
As others have said, moving water needs to be around 30 f to start freezing. This is why swift flowing rivers will not freeze until hell does.

Other water dynamics are a bit confusing and a great idea for a thread. As with most substances water becomes more dense as it cools. But water is odd because after it gets down to 39.2 f it is as dense as it will become and as it cools further it will become less dense and will rise in the water column. This is why ice floats. So in theory if you did an ice dive in deep water the deeper you go the warmer the water will get until it reaches a balmy 39.3 f.
 
I've only been ice diving in a lake. At 18 metres most of us read 4C/39F. Just underneath the ice some got readings around 32, which suits. So what's in between? Gradually 32-39F of course. Now most dive computers aren't precise enough to give us that. Unless you have some kind of layers with salty water which is heavier, you will not find any warmer water then 39F under the ice in a lake under normal circumstances.

Now you may have "lakes" with other than freshwater. I did some fishing in some called the Soap Lakes in WA many years ago. They had a ph of 8.5 probably loads of minerals, and the water might have a slight different freezing point than pure water for all I know. But the norm is a steady 39F at the deepest part of a lake, gradually warmer towards the surface in summer, and gradually cooler in the winter. If there's ice on top, the warmest water you'll find is 39F.

Isdykkerkurs
 

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