Learn from the ice-divers
Boiling bubbles at the surface of an inland site: John Bantin analyses a free-flow scenarioBack to Intro 16 Strategies for Coldwater Diving

IT WAS A CRISP SPRING MORNING. A low mist hung across the lake. Sarah and Jim entered the water, snug and warm in their drysuits.
ÂÂÂÂ It had been less than a relaxing walk from their car, loaded down as they were with enough weight to compensate for their thick undersuits. Jim gave his regulator a couple of squirts on the purge button to reassure himself that his air was turned on. Sarah put hers in her mouth and inhaled from it a couple of times.
ÂÂÂÂ Both of the divers were breathing quite heavily from their efforts as they immersed themselves in the water and enjoyed the weight of their tanks being lifted from weary shoulders.
ÂÂÂÂ Jim checked the temperature on his computer and saw that it registered 4ÂC. Dry gloves kept their hands warm and it was only as the chill struck the exposed parts of their faces that they appreciated how untenable this exercise would have been in an ill-fitting wetsuit.
ÂÂÂÂ They dumped the last of the excess air from their suits and commenced the descent. Jim took control of the winder reel of their SMB and Sarah let the line run through her hand as he deployed it. With visibility at less than 1m, to let go of this line would mean losing her buddy and the premature termination of their dive.

Jim was still breathing hard but his regulator gave him all the air he needed. As they reached 20m, he added some air to his suit. It suddenly started to give him rather more than he wanted, gushing forth in an uncontrollable free-flow. Ice had formed in his first stage, causing an uncontrolled increase in interstage pressure which his second-stage valve could not handle.
ÂÂÂÂ Jim abandoned his regulator in a cloud of bubbles and took hold of Sarahs octopus. It was not the best thing to do.
ÂÂÂÂ Doubling the air flow on it was bad enough, but concern about their predicament caused an inevitable increase in both their heart rates.
ÂÂÂÂ Heavier breathing by two people on one regulator already close to freezing was the final card that fate had to play. Sarah disappeared in a second cloud of bubbles as her regulator failed.
ÂÂÂÂ People on the shore were concerned. Huge amounts of air arriving at the surface indicated a crisis below.
ÂÂÂÂ However, Sarah was not about to make a drama out of that crisis. Tilting her regulator against her top lip so that excess air could escape from her semi-open mouth, she indicated to Jim to do the same.
ÂÂÂÂ Jim dropped his SMB reel and they both ascended the line, holding close together, breathing as they went and without panic.
ÂÂÂÂ They arrived at the surface irritated that the dive had been aborted but none the worse for the experience.
ÂÂÂÂSo what had they done wrong

Modern, high-performance regulators can deliver massive airflows with little effort. Beating the valve is something you usually only read about in ancient diving manuals. However, high-performance can create problems of its own.
ÂÂÂÂ When a gas such as the air you breathe from your tank passes from a high pressure to a lower pressure, it becomes colder.
ÂÂÂÂ The converse also applies, which is why newly filled tanks feel warm to the touch.
ÂÂÂÂ The air in your tank is under great pressure. Car tyres are rarely filled to more than a few bar but your tank is pumped to more than 200.
ÂÂÂÂ The first stage of your regulator lets gas pass at only 8-10 bar more than ambient pressure, so the pressure drop causes the air to get very cold.
ÂÂÂÂ If you are in water only a few degrees above freezing, your very cold first stage can cause localised icing, and in some cases this ice can cause the mechanical parts of your regulator to stick.
ÂÂÂÂ Most modern regulators are of a downstream design. If they fail, they do so in the valve-open position. Your air wont be cut off but you will get too much, which is preferable.

It is almost impossible to test for the coldwater performance of a regulator if you are looking for failure by icing. There are CE standards set but even these allow for a certain amount of free-flow and demand only a relatively short test duration. Its surprising to find that many regulators not designed for the purpose pass the CE coldwater test.
ÂÂÂÂ You cant tell how close a regulator comes to being affected by freezing until it freezes. Manufacturers design equipment to resist the effects of freezing but nothing is guaranteed.
ÂÂÂÂ Sitting on the edge of the Lac du Tigne in the Alps, I watched divers preparing to dive under the ice.
ÂÂÂÂ They were using all sorts of regulators, including some which had no coldwater spec whatsoever. Why did they not suffer these catastrophic free-flows Because they had been trained for ice-diving.
ÂÂÂÂ Firstly, they had been sure to fill their tanks with properly dried air, and kept them out of the cold until they wanted to use them.
ÂÂÂÂ This avoids dew forming and passing through with the air from inside the tank.
ÂÂÂÂ They were also careful not to breathe from the regulators in the air, passing freezing condensate from their mouths into second stages that were several degrees below zero.
ÂÂÂÂ Most importantly, they avoided massive airflows. They had two complete regulators on each tank set-up, whether they were using twins or H-valves.
ÂÂÂÂ The supply to their drysuits was kept separate from their primary breathing regulator. Some used a separate supply of argon for this, because it has a more effective insulating effect than air.
ÂÂÂÂ Finally, they limited their dive plans to depths from which they could ascend without the need for deco stops, should the worst happen. We can learn from these ice-divers, though I would add that it makes sense to use a regulator with a coldwater spec.

Sarah and Jim had been misled. Snug in their drysuits, they had failed to appreciate just how cold the air in their regulators was going to be. They had made matters worse by demanding large air-flows before and during the short dive.
ÂÂÂÂ Squirting air in his drysuit had been the final demand for Jims regulator.
ÂÂÂÂ Its not an unusual story, but incidents such as this wont always end so happily unless proper precautions are taken.

Back to Intro

16 Strategies for Coldwater Diving


hspace=3 Mark Ellyat specialises in extremely deep wreck dives, including a record-breaking dive on the Baden in the cold waters of the Channel Islands.

Drysuits are perfect for staying warm in any conditions, and a range of undersuits are all thats needed. The lower the temperature, the greater the thickness or tog-rating of the undersuit youll need. Modern undersuits should be water-tolerant. Many thinsulate and synthulate types offer nearly 80% of their dry warmth when soaked!

Its a myth that decompression cannot be completed in a cold, flooded drysuit. Ive done more than three hours of deco in a flooded suit in water of 12ÂC, with no bends incident. But I believe that if Id left the water when I felt chilly, that would have guaranteed DCI.

More recently, I completed a dive of more than three hours in water of 8-9ÂC. With the right drysuit/undersuit choice and some argon suit inflation I actually felt warm after the dive. I had a small fluffy pad taped over my kidney area and stomach to add insulation.

No thickness of undersuit can help someone who always feels the cold, but regular aerobic exercise will improve circulation and help give that Ready Brek feeling.

Divers must avoid sweating in their drysuits before a dive as this will chill later and make you colder. And my last tip is: dont pee in your drysuit. While pee is warm for a minute, its cold for much longer!

hspace=3 Zaid al Obaidi is a top UK wreck-diver. Zaid spent more than five hours in the Atlantic after diving ss Carpathia.
I work on the basis of layers. For the Carpathia dive I was wearing a Bowstone fleece and a woollen jumper underneath an Otter undersuit and Otter drysuit. These days I also use a Fourth Element Xerotherm as a base layer.

The Bowstone fleece is a sleeveless version of one of those woolly-bear things. It looks like a grown-up version of a Babygro but its great for keeping your core warm.

Gloves are very important. The best ones around seem to be the Scubapro semi-dry gloves, because they have excellent seals which prevent water flushing through them.

On the boat I always wear a hat - I have four or five different ones. My favourite is a blue and red Bowstone fleece hat.

hspace=3 Maz Kelly led a diving expedition to Norway in 2002 and will be diving inside the Arctic Circle on her expedition to Narvik this year. She dives mostly in the UK.
Get a good undersuit - I dive in a Weezle. A good beanie hat is a must. Ive got a fleecy one from Accessorize with a quilted lining.

Making sure you feel warm before a dive seems to help. When we were training up in Oban we used to run around and get plenty of exercise beforehand. If you feel cold after a dive, getting into your car and having a cuddle warms things up. Failing that, a bacon sandwich and a thermos flask of tea!

I use argon for suit inflation and it makes a difference. I did a 90 minute dive in Stoney in February which was so cold I could barely feel my hands or use my legs to get out at the end, but theres no way I could have done that using air in my suit.

Going diving if you feel chilled from a previous dive is a bad idea, even if youre diving in warm water. My partner Alex was mildly hypothermic after a series of long dives on the Thistlegorm. I had to wrap him in blankets and get him to drink lots of hot liquids. It took ages to get him to stop shivering.

hspace=3 Carl Spencer is an adventurous technical diver who spent many hours in Lake Coniston on the Bluebird project.
Ive designed my own undersuit-heating system. It uses a heated waistcoat designed for motorcyclists and its highly tolerant to moisture. The power supply is a home-built battery and canister based on an HID torch. An umbilical cable attaches to the waistcoat through my drysuit, with an external switch on the chest area.

The key component is the switch, which I had to source from the USA, but all the other parts are readily available. I just switch it on for a couple of minutes every half-hour or so. More than that and you start to sweat! I just use it to keep myself comfortable on long dives, because Im often in the water for more than two hours.

hspace=3 Tara Kelly is a BSAC instructor and keen UK diver who has organised diving expeditions to Alderney and St Kilda.

Wear good underwear beneath your undersuit! Id recommend Sloggi - very comfortable. It does everything from thongs to full-size Bridget Jones support knickers for when youre feeling less toned. I recently got the Fourth Element Xerotherm, which is really toasty.

Being out in the cold makes my eyes stream and diving in cold water makes my lips crack up, so Im a big fan of Elizabeth Ardens 8 Hour cream, which I put on my eyes and lips before I get on the boat. Carnex, which comes in a little yellow pot, also does the trick.

Booking a good, comfy boat is another essential. You need a skilful, attentive skipper who will pick you up quickly when you surface and dish out hot drinks and biscuits. Im a big fan of Ivor Jansens Protector (out of Weymouth) because hes a great skipper, has the kettle on ready for when you surface and even offers hot Ribena. His wife Denise provides hot soup in the winter. Thats the kind of customer care I really appreciate!

hspace=3 Teresa Telus is a top technical diver who has been on several expeditions to the Lusitania, and is taking part in an expedition to HMS Russell (120m+) in 2003.
I have a huge respect for cold water and dives that involve long hangs. A believer in layers and comfort, I found last year that I should have bought a new undersuit years ago, as my old thinsulate obviously wasnt working any more.

When it gets really cold I also don a Polartec all-in-one wicking thermal next to my skin - not at all flattering, but it works.

I cut back my in-water time to maintain dexterity in my hands throughout the dive. Being so cold that you cant disconnect a problem hose could get you in real trouble.

I must admit that when I had a 50W halogen lamp I would put it on during the deco and hold my hands tightly over the head to warm them up! If your extremities get really cold you wont off-gas as quickly, so I consider this when deciding how much conservatism to plan into my decompression.

I also check my seals and zips and have them serviced and replaced far more regularly than I used to. A couple of years ago a trimix diver had serious DCI when he had a suit zip failure that resulted in him aborting a lot of deco because he was so cold. He had to be treated for hypothermia before they could treat his DCI.

When it comes to drysuits, for years I preferred latex seals because the old neoprene ones always leaked, but my new O3 suit has neoprene seals and theyre great, much warmer. The new suit is also of slightly thicker neoprene. Its still only 2.5mm, but its definitely more insulating and doesnt have any detrimental buoyancy problems, either.

Obviously using a rebreather keeps me much warmer than diving on open-circuit. Finally, good-fitting incontinence knickers are a must - yuk!

hspace=3 Justina Cronin works at Stoney Cove as an instructor, so has plenty of experience of repetitive dives in cold water.
Instructors tend to feel the cold because were in the water often and spend a lot of time sitting still and watching the students.

My top tip is this: always keep your neck warm. I have a membrane suit with latex seals, so my wrists and neck can easily get cold. I wear a hood that extends over my neck seal and tucks into a Ôwarm neck fastening on my drysuit. I also wear neoprene covers over the top of my wrist seals.

I tried dry gloves but found them too bulky, so I use 5mm neoprene gloves. I find that if you keep the rest of your body warm, your hands will stay warm too.

Cold really seems to make a big difference when temperatures drop below 10Â. A dive in 11Â water feels quite tolerable, but if the temperature drops just 2Â, the impact is huge and its easy for divers to underestimate the consequences.

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