Good points, Mark. Virtually every news story I read about paddlers dying after a cold-water capsize describes them as "experienced" or "very experienced". Maybe they were, but that certainly doesn't mean that they were knowledgeable or safety-conscious. The terminology that the U.S. Coast Guard uses to describe buoyancy devices appears to be in a state of flux, with the term "lifejacket" beginning to be used interchangeably with PFD. I agree that any distinction needs to be based on real-world conditions.
In Essentials of Sea Survival, Golden & Tipton note that "To qualify for "life-jacket" classification in the UK, adult life-jackets must have in excess of 34lbs of buoyancy." Lesser devices are termed "Buoyancy Aids". On our side of the pond, the Coast Guard doesn't list a single device with buoyancy in excess of 34lbs. The closest ones are Type 1 Inflatable (33lbs), Type II Inflatable (33lbs, and a Type V - Special Use Device - Inflatable (22lbs to 34lbs).
The Coast Guard's information on "RECREATIONAL BOATING PFD SELECTION"
is here: http://www.uscg.mil/hq/cg5/cg5214/pfdselection.asp
and the terminology, while it sheds no light on our life jacket vs PFD discussion, is pretty interesting. In the interest of space, I'll stick to Types I, II & III. Incidentally, no mention is made of supporting the wearer in a face-up position. TYPE I PFDS / OFF-SHORE LIFE JACKETS:
Best for all waters, open ocean, rough seas, or remote water, where rescue may be slow coming. Abandon-ship lifejacket for commercial vessels and all vessels carrying passengers for hire:TYPE II PFDS / NEAR-SHORE BUOYANT VESTS:
For general boating activities. Good for calm, inland waters, or where there is a good chance for fast rescue.TYPE III PFDS / FLOTATION AIDS:
For general boating or the specialized activity that is marked on the device such as water skiing, hunting, fishing, canoeing, kayaking and others. Good for calm, inland waters, or where there is a good chance for fast rescue. Designed so that wearing it will complement your boating activities.
So we have Lifejackets, Life Jackets, Off-Shore Life Jackets, Near-Shore Buoyant Vests, and Floatation Aids, which leaves plenty of room for confusion. The Coast Guard seems to be aware of this, because they have the following disclaimer at the bottom of their page:
"The Coast Guard is working with the PFD community to revise the classification and labeling of PFDs. When completed, this information will be updated and hopefully be somewhat easier to understand."
One thing I find particularly interesting is the recommended use for Type IIIs: "Good for calm, inland waters, or where there is a good chance for fast rescue." The Coast Guard also has a Cold Water Survival link on their PFD page:http://www.uscg.mil/hq/cg5/cg5214/pfdselection.asp#DEFINITIONS
That section places all its emphasis on hypothermia, and makes no mention of cold shock, cold water incapacitation, or swimming failure. It also includes a typical survival timetable, which states, for example, that at water temperatures of 40F - 50F, the victim will be exhausted or unconscious in 30 - 60 minutes, and it gives an "expected time of survival" of 1-3 hours. This information is simply unrealistic and misleading and does little or nothing to promote cold water safety.
Among other inaccuracies, this sort of survival timetable treats "exhaustion" and "unconscousness" as if they were synonymous. In fact, exhaustion or physical incapacitation can occur in under ten minutes as a result of the chilling effect of cold on nerves and muscles. Unconsciousness due to hypothermia is a different phenomenon, a function of core temperature decline - specifically cooling of the brain - which takes much longer. Further confusing the issue is the fact that survival times are computed on an entirely different basis - the theoretical temperature at which heart failure would occur.
In terms of survival, the real world paints a much bleaker picture. Although the Coast Guard warns that "if your body temperature goes too low, you may pass out and then drown", cold water drowning very rarely has anything to do with hypothermia, and everything to do with cold shock, physical incapacitation, and swimming failure. With few exceptions, these will occur in under 30 minutes. The sobering truth is that in cold water, unless a person is very fat and can swim, without a buoyancy device they will drown, often immediately. There's a good reason why drowning due to cold shock used to be called "Sudden Disappearance Syndrome".
While this is an excellent argument for always wearing your buoyancy device (whatever type it may be), even one that supports an incapacitated person in a face-up position is very unlikely to prevent that physically helpless person from drowning if waves are present. A Type III may fail to do this even in relatively calm water. What's more, it's entirely possible for a person to lose the use of their hands within a couple of minutes following immersion in cold water. Picture reattaching your sprayskirt, pumping out your boat or, for that matter, paddling, while wearing boxing gloves on your hands. Unprotected cold water immersion is an immediately life-threatening event. That's the reality we should be presenting to all recreational boaters, particularly those in the paddling community.