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The last line of defense?

Oct 20, 2010

When you ask yourself the question, “are survival suits safety overkill?” the answer depends upon the type of sailing or power cruising you pursue.

The ISAF Offshore Special Regulations mandate immersion suits for those participating in Category 0 (transoceanic) races and recommends them for shorter oceanic Category 1 races where the risk of hypothermia becomes an elevated concern. Commercial mariners operating during colder months carry them aboard coastal vessels and fishing fleets, and have learned the hard way about the value of well-maintained survival suits (currently more often called immersion suits). In essence, these hypothermia-postponing garments, along with an EPIRB and life raft, represent the last resort in a mariner’s bag of tricks.

When and if it comes time to use one, there’s no room for slipups. Zippers need to work and the person donning the gear needs to know just what should and shouldn’t be worn underneath the suit. Most immersion suits are built to specific standards spelled out by the U.S. Coast Guard and ISO regulations. SOLAS compliance remains, however, the gold standard of immersion suit approval.

At first glance, these suits appear to be heavy duty wet suits with built-in boots, gloves and a hood, but a closer look reveals a far more technical piece of gear. For years the reigning design theory utilized a neoprene fabric that was carefully stitched and glued in order to make all of the seams watertight. The design was a thicker version of what was used by divers and surfers, but the principal of operation was very different. Instead of functioning as a conventional wet suit, trapping and warming a thin layer of water between the wearer’s skin and the neoprene, these immersion suits were designed to keep the water out. Insulation in this older style of suit was provided by the thick neoprene as well as the clothing worn under the survival suit. Its loose fit and the tight seal around the face of the user is another difference between it and a conventional wet suit. The baggy fit makes it easy to slip over clothing, but the sealing zipper needs to be waxed and free of corrosion in order to make it easier to operate.

Zipper maintenance is a big deal, and if left un-inspected, ambient humidity in a salty environment can cause enough corrosion to jeopardize its operation. Each manufacturer details how to maintain their product’s zipper. Some recommend waxing the teeth while others offer a special lubricant. There have been abandon-ship incidents in which crewmembers have perished because of a corroded survival suit zipper. Loss of life resulting from the lack of such simple maintenance is tragic, and all new suits come with written reminders about zipper maintenance and the importance of dry storage of survival suits. These zippers are part of the waterproof seal of every suit and even when well maintained, most take 10 to 20 pounds of pull to initiate the closure.

In the last decade there has been a shift away from heavy neoprene toward lighter polyurethane-coated nylon outer skins with insulation derived from both an inner liner and the layers of clothing worn by the person donning the suit. The Gumby feel of the bag-like suit has been reduced and the new nylon/PU garments are more flexible and less constricting. All of the available products come with built-in booties, and though they may not be a fashion statement they will keep water out and provide some traction on a wet slippery deck. One of the most important considerations for sailors and power cruisers alike is retaining manual dexterity, and suits that come with removable gloves rather than built in mittens go a long way to enhance this capability. Traditional neoprene suits with attached gloves and boots imprison the wearer in a warm watertight cocoon that eliminates all but crude grabbing and holding dexterity. This causes tasks like making a mayday call on a radio, firing flares, or opening a locker impossible to accomplish.

The one-size-fits-all impression, conveyed by the size label stamped “universal,” can be more than a bit misleading. Yes, most suits have a high tolerance for height and weight variation, but head size is also a very important factor. It influences the crucial seal around the wearer’s face, and if the hood is too large, water can enter the suit. For example, two suits marketed by Stearns and the Mustang Ocean Commaner are defined as “universal” in size and appropriate for those from 5 feet to 6.5 feet and from 110 to 330 pounds in weight. At either of the extremes in this size range head seal, boot size and wrist seal could become an issue. So the bottom line is just as you would never buy a sports jacket without trying it on, the same holds true for survival suits.

Over the years I have tested a lot of immersion gear and found that subtle differences can be a big deal. One survival suit I was trying to put on had plenty of room in the torso and legs to accommodate a user wearing a shirt and polar fleece, but I was unable to pull the sleeves over my forearms while wearing the thick polar fleece. Having to remove the fleece to get into the suit and give up the extra insulation the garment offered was a big disadvantage. Many women find the face seal on universal sized suits to be much too loose. Testing the fit of a survival suit prior to purchase is worth the time and effort.

Modern fibers and a layered approach to thermal insulation offer a cumulative benefit. And if time allows, a mountaineer’s approach to layering works best. Shoes must be taken off, but doubling up on socks makes sense. Most suits won’t accommodate a heavy jacket. However, thermal underwear, along with fleece pants and a pullover usually fit, ensuring that the layering logic will pay off. Survival is all about body heat retention and the avoidance of radiational cooling. The standard for most immersion suits is to provide a minimum of six-hour survival time in 0 to 2 degrees C water with no more than a 2 degree C drop in core temperature. Person-to-person differences in metabolic rate and body fat make such statistics a generalized target rather than an unyielding benchmark. However, it’s clear that the better the insulation and the drier one remains, the longer the survival time.

I have had a chance to spend time in icy water testing survival suits and have found a few variations in design and approach to construction among products available, but the bottom line is that they all get high marks for extending life in a environment that is unforgiving.

Buddy tethers, clips, purge valves, reflective tape and buoyancy aids round out the list of extras attached to the basic immersion suit. High quality SOLAS reflective tape glows bright white when a spot light hits it and can mean the difference between being spotted or overlooked. Purge valves vent excess air and help the victim attain an effective trim angle.

After looking at how buddy tether straps work on some suits, I had a bit of concern about ending up captive to something more than your shipmate. In some cases these webbing tethers are permanently stitched to the suit and if they tangle around rigging or a stanchion, a sinking vessel can drag along more than what should be attached to it. This issue is eliminated on suits with releasable buddy tethers, otherwise a sharp knife is the only fix.

For the same reason, inflatable PFD/harness designs usually incorporate a removable quick disconnect at the proximal end of the tether. Most immersion suits allow you to use your removable harness tether on the D-rings attached to the suit. Attempting to wear an inflatable PFD/harness over an immersion suit is often counter productive due to the inability to adjust its size, but transferring the tether to the immersion suit does make sense.

Another issue to consider is whether a top-of-the-line dry suit with add-on wet suit boots, gloves and a hood can be a stand in for a survival suit. The ultimate answer is “not quite,” but a dry suit is a lot better than jumping into the cold ocean wearing foul weather gear.

In fact after testing a Gill dry suit in icy winter water I found it to be about 80 percent as effective as an immersion suit and much more easy to wear. This type of dry suit is a superior garment for heavy weather watchkeeping.

When it comes to the ultimate gamble of going into the water and when severe hypothermia is the opponent, a well maintained immersion suit is still a mariner’s best bet.

Ralph Naranjo is a freelance writer and photographer based in Annapolis, Md. Naranjo is also part of U.S. Sailing’s National Faculty and a past chairman of its Safety at Sea Committee.

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