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Basic Training: Cold Water Diving

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As you are reading this article, in many areas around the world there is snow on the ground and the water is pretty cool or even downright cold. Cold water diving can and does take place all year round.

By James Lapenta

How a diver defines cold water is highly subjective. Some consider anything under 80 degrees F/27 C to be cool water. Make no mistake, it is possible to get hypothermic in these temps. Others see 54 F/ 12 C (common in the Pacific off California) as cold. Those who dive the Great Lakes and Northeast US quarries view that as balmy compared to the 40 F/4 C or lower bottom temps we commonly see. For purposes of this article I’m going to use a cut off of 50 F / 10 C as the definition of cold water.

One reason has to deal with equipment. Most manufacturers of regulators have use guidelines. A common recommendation for non-environmentally sealed units is to not use them in water temps below 50 F/10 C level. This is due to the possibility of the 1st stage icing up should the flow rate through it be too great. Either from a free flow or the diver over breathing the reg. There have been numerous fatalities and near misses because divers were using unsealed or warm water regs in cold water.

The terms “cold water” and “warm water” are actually not correct when talking about regs. The correct terms are “environmentally sealed” or “not environmentally sealed” and more accurately reflect what “sealing” does. A sealed reg does not allow the environment (water, salt, sand, silt, etc.) to come into contact with the internal parts of the regulator. If you don’t have cold water coming into direct contact with the internals the chance of icing is reduced. That’s the simple version. The long version is something to discuss with your regulator service person.

Going into cold water requires a sealed reg. Using an unsealed is risky and in one quarry actually prohibited for deep dives into the colder waters. Regulators for cold water should also be well maintained and checked before using them. One of the items to check is the intermediate pressure. If the IP is too high in warm water you may not notice a problem. In cold water the increased pressure may result in the reg failing and icing up resulting in a free flow. The IP is not hard to check and a good IP gauge is around $20. It plugs into the LP inflator hose and can be verified in less than 2 minutes. Check you reg specs to see where the IP should be.

Second stages should be tuned so that they are not free flowing nor hard to draw air from. They should also be checked for the amount of effort (cracking) that is needed to get air to flow. Another easy item to check and there are numerous videos on how to do this with a sink full of water and ruler. Also, another good way to determine if the reg needs serviced. I prefer second stages with adjustment knobs. The larger the better for use with thick gloves.

The BC you choose is important. With thick wet suits and dry suits, more lead is needed. The BC should have sufficient lift to ensure you can remain in control on the surface and at depth. The most versatile BC’s for cold water allows the diver to distribute weight among multiple systems to reduce the risk of a rapid ascent should one of those systems fail. Some divers make the mistake of loading all their ballast into weight integrated BC pockets.

This is dangerous and makes the unit unwieldy on land. Better to put some of that lead on a belt and choose a BC that doesn’t have a lot of it own inherent buoyancy due to unnecessary padding and poorly designed air cells that trap air. Back plate and wing style BC’s offer versatility, little or no inherent buoyancy, and can be adjusted quickly to fit the diver.

Though everything acts a unit, exposure protection is perhaps the most important component. If you can’t be warm you can’t dive and the choice of reg and BC is moot. While some divers do dive wet in cold water, it is not the ideal choice and adds unnecessary risk. Not only for them but also for the people they dive with. That 50 F/10 C or similar temp is where many divers draw the line at wet vs dry. Personally, if it’s below 70 F/ 21 C I’m diving dry. A 7mm or thicker suit is too much trouble when I could be much warmer in a dry suit.

A drysuit is the best way to ensure cold water diving experiences are enjoyable. Both under the water and on the surface. Dry suits insulate with air and undergarments rather than neoprene with a layer of water between it and the skin. They are available in many styles and types. The most common type in use today is arguably the shell suit. It is a relatively thin waterproof shell that uses varying types and thicknesses of undergarments to keep the diver warm. Varying the undergarments allows for the suit to be used in anything from 80 F/27 C water down to 36 F/ 2 C or even colder.

Dry suits do take some getting used to and a training class with a competent instructor is highly recommended. I am actually the author of the SDI Drysuit course and over half of my close to 1000 dives is in one. Just because the air and water cool down, doesn’t mean your diving has to slow. Take proper steps for cold water and you’ll discover that it’s a lot of fun.

About James Lapenta

James Lapenta – Scuba Instructor, Author

James Lapenta from Canonsburg, Pennsylvania, a Diver, dive Instructor, Author and owner of UDM Aquatic Services has been diving since 2004.

He is a Scuba Educators Instructor # 204, SDI/TDI Instructor # 16810, CMAS 2 Star Instructor # USAF0012000204

For more on basic skills and education pick up a copy of either of my books

SCUBA: A Practical Guide for the New Diver or SCUBA: A Practical Guide to Advanced Level Training on Amazon. Dive Safe.

Dive Safe.