I'd like to see charts for various proposed survival times for different PFD's like float coats and the float coveralls, which I hadn't even heard of before. And what about various, such as wearing a hat, boots or other base clothing. Someone, somewhere must have looked into this? Maybe military.

It is tough to find that kind of information. One reason is that there are so many variables that it is hard to put together a meaningfull chart or graph. Note that even the simple charts that ireckon and I linked have a very wide range. Take for example the effects of wearing clothing. How much clothing? How many layers? Cotton, wool, poly pro, fleace, goretex? How well does it fit, snug, loose? Is the person fit or a couch potato? Skinny or fat? If so, how fat? Young or old?

Since I live in an area with cold water, and enjoy various water related activities, I've done a fair bit of reading on the subject. For whatever it's worth, below are a few observations. Note that cases 1-4, the differences in survival due to these factors are fairly small. For cases 5-7 the differences can be significant. Ranked very roughly from small effect to large effect:

1. Women have a slight advantage over men. (Different % of body fat?)
2. Being somewhat overweight is a slight advantage. (Fat gives a small bit of insulation.)
3. Almost any clothing you are wearing will help slightly. You loose heat by the water circulating around your body. Clothing slows down the water circulating past your skin and helps you retain a slight bit of heat. Wearing a full set rain gear over pile or fleece probably buys you a bit longer survival than being naked.
4. A float coat gives a bit of insulation. (Unless it fits too loosely.)
5. Float coveralls AKA a "work suit" (Type V PFD) gives quite a bit of insulation. (Snug up the ankles and cuffs to reduce water circulation.)
6. A dry suit over insulation makes a HUGE difference (many hours) in survival.
7. A neoprene survival suit (a "gumby suit") makes an even bigger difference in survival (many many hours).

One bit of info that may help is from Mustang Survival. See the chart with "clo values". Mustang gives a clo rating for some of their products.

AKSAR

Thanks for the info and the time it took to type.I'm familiar with the survival suits, but some of the others are new to me. I've seen the Mustang float coat but the fit on me was very poor. I'm assuming the work suits you mentioned are what I used to see the deck workers on Deadliest Catch wearing. You've given me more to to think about.Thanks again.

There are several version of a minimal, self inflating PFD.

I am late to the party, but since TeacherRO brought it back ---

It has been looked into extensively. Mostly at the University of Victoria in British Columbia. The most complete testing on human subjects was done in the '70s and led to: Hayward, J.S., Lisson, P.A., Collis, N.L., and Eckerson, J.D. Survival Suits for Accidental Immersion in Cold Water: Design-Concept and their Thermal Protective Performance. Dept. of Biology. Univ. of Victoria, B.C. 1978. I have not found a copy online and don't know if I can find my copy, but testing was done in Victoria Harbor on students wearing several different types of clothing. As you might expect wool was better than cotton (but not as much as you might expect) and the fit of the clothing made a difference but again the activity was more important (see below). Human testing of this sort will probably never be done again, but it was a sea change in our understanding of immersion hypothermia.

This work led Hayward to develop what is now the Mustang ThermoSystem Float Coat. The beavertail (or diaper at is commonly called) changes a moderate increase in survival time to a huge one (the modern coat is even better than the original). I have used one for many years and would not be comfortable offshore in cold water without it. I have had it in the water many times (for practice, my only sinking ship I got off with dry feet). Mustang makes several other coats so fit of one may not control fit in the ThermoSystem.

The following is a bit of information from this work that was printed in a pamphlet by Hayward through the Sea Grant Program at UBC. ir.library.oregonstate.edu/xmlui/handle/1957/24392?show=full

SUMMARY
The following table summarizes how a selection of
different situations can affect predicted survival time
of the average adult* in water of 50OF (100C):
Situation Predicted Survival Time (Hours)
NO FLOTATION
Drownproofing 1.5
Treading Water 2.0
WITH FLOTATION
Swimming 2.0
Holding-still 2.7
H.E.L.P. 4.0
Huddle 4.0
UVic Thermofloat 9.5
*Clothing worn was cotton shirt, pants, and socks, plus
running shoes.

Respectfully,

Jerry

How much suffering did a student have to endure to get an "A"?

Another enthusiastic vote for the Mustang Float Coat. I wore one a lot while bouncing around the Channel Islands, in and out of the water, sometimes right in the surf. My model had a beaver tail and I would recommend one for any serious purpose.

When kayaking in cool waters (40s or soF) my preferred rig was a float coat, combined with a farmer john 1/4 neoprene wetsuit bottom.

Jerry,

While I think you and I mostly agree on the general aspects of cold water immersion, I have to take issue with a few specific points you made. I have highlighted in bold the specific points I want to address.
There has in fact been a great deal of human testing done since the '70s. In particular, Gordon Geisbrecht (AKA "Prof Popsicle") at Univ of Manitoba has done many experiments, both on himself and students. One difference from the older work at UBC is that by using modern electronics, Geisbrecht and others can now monitor core temperature in real time. For a list of some of Geisbrechts many publications go here. For graphic views of some of his human subject testing, see Cold Water Bootcamp (Canadian version], and Cold Water Bootcamp USA. I highly recommend getting a copy of the "Beyond Cold Water Bootcamp" DVD. It has some remarkable footage of circum-rescue collapse.

I presume this is a typo and you meant 50 F and 10 C? (500F is about the temperature that paper burns, and 100 C is the boiling point of water.)

This seems to imply that a PFD makes no difference, and you can survive about 2 hours with or without a life jacket? Geisbrecht's work has made it abundantly clear that a PFD makes a huge difference. Without a PFD, cooling of the limbs makes it difficult or impossible to swim long before your core cools to even mild hypothermia. Without a PFD in cold water you can't swim long enough to become hypothermic, instead you drown first.

I totally agree that a float coat is a great idea if one is around cold water. Floatation coverals (a work suit) is even better. A full-on insulated dry survival suit (a "gumby suit") is best of all.