winter diving tips?

fubari

What should I be watching out for on cold weather dives?
My unit is an inspiration classic.

I've read that extra pre-breathing is good to bring the
scrubber up to a reaction-sustaining temperature.
How long do you cold weather divers pre-breathe
in the winter?

Any concerns w/calibrating in cold weather?
Is it better to calibrate indoors in a warm environment?
Or just before the first dive?
I ended up calibrating in -10C (14F) just before the dive,
after the unit stood on an open boat deck for an hour
prior to calibrate + pre-breathe.

The lcd's were sluggish, but read the way I expected.
Air pressure was guesstimated at 970mbar, 100% O2 at 97%
for the flush fudge-factor.

Water temp at depth (25M max (80 ft)) was 4C (40F).

At 20' I found I was getting a PO2=1.5 on an oxygen flush,
so I'm wondering what to do procedure-wise to get a
better cal. Cells were new as of June, I'd be pretty surprised
if they're current limited yet.

Exposure-wise, I was fine. This was a simple dive, 50min total
bottom time. Practiced some basic skills - nothing fancy
for now, I just want to get some flight time operating the
unit so I'm not starting from square-one when Spring comes.

John G.

nigelh

The only problem I've ever had was out of the water when the handsets froze up. That is the damp from the previous days dive froze solid and the switches wouldn't slide.

In the water it was business-as-usual and a darn sight warmer.

I don't do any extra pre-breath. My emphasis is on keeping me warm and sitting on the side once I have seen everything stabilise just seems counterproductive.

__________________
nigelh

jukkao

I always do the calibration beforehand in warm conditions and I try to keep the unit inside a car etc. for as long as possible before going out.

Earlier I sometimes got some strange readings and/or slow reactions while calibrating in cold.

Jukka

Ken

Second that suggestion. We found that having a a hut, or a tent with propane and hot water tremendously helpful for those occasional thawing events and protection from harsh-freezing wind. Brrrrh.

jukkao

A tent above a wreck is very nice, nobody gets seasick as the ice cover is so stable.

It is also good to have some hot blueberry soup or coffe with cream if the suit zipper would not open because of ice.

Jukka

Buddha Boy

Hey John,

When you practised your skills in cold water, which I presume means you did some 'mouthpiece out' stuff, did you have any problem rotating the mouthpiece shut before removing from you mouth?

My bud and I both had problems last winter getting the mouthpiece to shut in 6 degree or below water. We put it down to the (very small amount of) silicon on the o rings solidifying and preventing the sleeve from rotating.

Any thoughts?
Cheers

Pete

Andrew-John

Building an eskimo igloo on the ice is far better idea than bringing a hut or a tent there. It's a pity that we have lost some of our ability to contsruct dome shaped (like the Egyptians and Eskimos) structures even though we have CAD-systems.

I think that mastering well transportation speed over an uneven ice field is essential. It can save us from a number of problems before and after jumping in there.

Anrew-John

__________________
The Truth is
down There!

deepnark

WE DIVED THIS WEEKEND IN -6 PLUS WIND CHILL .I GAVE THE UNIT AN EXTRA 2 MINS PREBREATH TO BE ON THE SAFE SIDE ,AND APART FROM FREEZING MY ASS OFF WAITING TO GET TO THE WRCK SITE IT WAS A NORMAL DIVE FOR THE UNIT.

RAY

Andrew-John

Minus something?

__________________
The Truth is
down There!

fubari

r.e. mouthpiece: I haven't tried that yet in cold water yet, and I'm
stuck on land until later this January. I'll be interested in trying that.

lube-wise, I've gotten in the habit of dabbing a spot of christolube
on anything that need to be lubed; I'll be curious to see how
that works in the cold.

John G.

p.s. thanks for the ideas, everyone.