According to what I've been told by cold water survival folks in the Navy med research branch, you don't warm a hypothermia victim using body heat from another person. The result is that you warm the victim so slowly, that the surface tissues warm just enough to cause the blood vessels to open up which causes the warm blood in the body core to migrate to the colder extremities and surface layers, thus actually cooling the victim further.

As I've been instructed, the best bet in a life raft situation is to wrap the person well, insulate if possible, and if conscious, administer warm sweet liquid. From the information provided to me by BUMED, hypothermia victims can recover their body heat as soon as heat loss is stopped.

It simply is not practical to pack some sort of warming device in raft. Several posts here about the MRE heater pretty well explains that methods. Putting a compressed flammable gas stove in there creates a whole host of new problems and hazards.

We recommend that some of the food bar be crumbled into the water and the water warmed by body heat of another survivor and then administered to the victim. The food bar is very high in carbs and is sweet.

Putting too much bulky survival gear in the raft starts affecting the inflation reliability. If the raft doesn't inflate, then the gear is moot.

Regards,

Tom

Can anyone name the oldest liferaft mentioned in literature? The design parameters issued 'from above' must have been pretty good, one of our first modern battleships, BB-3 USS Oregon's architect using those exact measurements in it's design. Oregon was mostly remembered for it's superb ridability in rough seas.It was stripped and welded up as a floating ammunition dump in WW2 in the Pacific. It broke free from it's berth in Guam during a Typhoon that sank manned and manuevering ships and was found floating 500 nautical miles away unscathed. The idea of a manueverable, powered liferaft or dinghy comes from the same mindset as a lost hiker 'walking out.' Captain Bligh or Shakelton aside,survival resources are better designed around 'hugging a wave' and staying put near your last known position for rescuers.Many ships in fact will launch their ship's boats if possible and these can act as 'herders.' As for the RN and it's traditions? Many of our modern lifeboat ideas came from a lowly RAF rank named Shaw after witnessing a bungled launching of lifeboats. He had another name, Colonel T.E. Lawrence, late of the army.

In the case of the General Belgrano, those who boarded the rafts survived. The sea anchor (drogue) does give the raft attitude control to keep its bow into the wind. The rafts are also packed with a spare sea anchor to provide additional drag if desired. There are requirements for USCG/SOLAS raft designs that they are able to be maneuvered to some degree with the paddles provided. Plus there are designated marshalling boats on every ship help draw the rafts together. The life rafts we're using are a good bit bigger and better equipped than most yachting rafts.

You've seen some British ships with the totally enclosed lifeboats (TEL). Could you imagine trying to equip an aircraft carrier with TEL's for over 5000 people? I doubt the Royal Navy is providing even 100% TEL coverage for their large surface combatants. Even cruise ships don't provide that level of coverage with lifeboats. They always make up the difference with inflatables. The company that provides the U.S. Navy with inflatable life rafts, also provides rafts to the RN, as it's a British owned company.

I think describing the life rafts as "glorified kiddie floats" grossly understates their value as a life-saving tool. Granted, they are not a perfect solution, but they do seem to work for most of the cruise lines which have on occasion been obliged to use them.

Cheers,

Tom

I'm not sure about that, but I can give some info on early inflatables.

1855 designs by Charles Goodyear




Earliest known USN inflatable life raft design used onboard ironclad monitors during the American Civil War

It's possible that this raft design may have been used on board the sloop of war, USS Constellation, in the 1850's.


Life raft which sailed from New York to England in 1866.

This raft voyage is also mentioned in literature, The Voyage Alone in the Yawl Rob Roy by John MacGregor.

Regards,

Tom

"Can anyone name the oldest liferaft mentioned in literature? The design parameters issued 'from above' must have been pretty good, one of our first modern battleships, BB-3 USS Oregon's architect using those exact measurements in it's design."

Noah's Ark? But the measurements are off.
And God said unto Noah, . . . Make thee an ark of gopher wood; rooms shalt thou make in the ark, and shalt pitch it within and without with pitch. And this [is the fashion] which thou shalt make it [of]: The length of the ark [shall be] three hundred cubits, the breadth of it fifty cubits, and the height of it thirty cubits. A window shalt thou make to the ark, and in a cubit shalt thou finish it above; and the door of the ark shalt thou set in the side thereof; [with] lower, second, and third [stories] shalt thou make it. " (Gen. 6:13-16)

A cubit is the distance between an adult's elbow and tip of the finger, generally 18-inches. Most Hebrew scholars believe the cubit to have been between 17½ -21½ inches long. This means that the ark would have been 450 feet long, 75 feet wide and 45 feet high if the 18 inch cubit was used. If a larger cubit was used it would have been proportionately longer.

USS Oregon Length: 348 feet Beam: 69 feet 3 nches Mean draft: 24 feet

I think you may need to go back to the folks at the Navy med research branch and get some more feedback on treating hypothermic victims. The best way to treat hypothermia non intrusively is to warm the air the hypothermia victim is breathing in. Having a second person together with the hot water bottle in something like the Blizzard Tube (an effective vapour barrier) is to warm the air inside the Tube itself. The warm moist air generated by the fit healthy crew member will then warm the victims lungs/thoracic part of the body and will help speed the warming of the thermoregulatory part of the brain called the hypothalamus. This will more than compensate for the effects of dilating peripheral blood vessels.
Getting the victim out of cold wet clothing is just as important and this will dramatically reduce the heat loss due to the wet clothing. Rapping the victim in a simple space type blanket will just not work with air temperatures below 10-15 degrees Celsius.
This is why all UK arctic warfare unit members are instructed to keep a spare set of clothes in a dry bag in case of immersion in icy water.

As you have mentioned a hot drink does not look possible due to the HAZMAT regulations despite the fact that gas cartridge failure rates are extremely low compared even to lithium battery incidents. Could the hypothetical hypothermia kits be deployed separately from the deployment of the life rafts?

A good guide to treating hypothermic casualties is available at http://www.hypothermia.org/Hypothermia_Ed_pdf/Alaska-Cold-Injuries.pdf

Interesting to see your comment about stripping wet clothes as I always thought the same and was suprised to read this on the Blizzard site:

"RAF Mountain Rescue’s New CASWRAP System

The RAF Mountain Rescue Service (MRS) has developed a new system to treat and prevent hypothermia while evacuating casualties. Called CASWRAP, it is now being used by all personnel in the UK. Instead of stripping wet clothes from casualties, teams are now trained to wrap them immediately in a Blizzard Survival Bag or Blanket.

More Insulation
They cover this with a conventional sleeping bag for more insulation, then add a second Blizzard Survival Bag or Blanket as an outer layer. When a conventional bag is added as an intermediate layer, even casualties who are soaked warm up rapidly and are fully protected from wind and rain."

Although I suspect is may be more to do with the lack of a controlled enviroment on a mountainside with potentially serious windchill as they also have this on another page, so it seems opinions vary:

"US Army medics are now trained to wrap casualties in Blizzard Survival Blankets as their first response to preventing hypothermia in trauma cases - even in hot weather.

Tens of thousands of Blizzard Survival Blankets are being incorporated in a new Hypothermia Prevention and Management Kit™ (HPMK NSN# 6515-01-532-8056), developed by US military medical equipment specialists North American Rescue Products (www.narescue.com). The HPMK further enhances the Blizzard Survival Blanket's effectiveness with the addition of a self-heating pad and a thermal skull cap.

The Blizzard Survival Blanket is recommended as the first choice for keeping casualties warm by the 2007 Prehospital Trauma Life Support Military Version Sixth Edition (PHTLS Military Version 6E), produced by the globally respected National Association of Emergency Medical Technicians (NAEMT).

PHTLS says medics' initial response to trauma cases should be: “After any immediate life-threatening issues are addressed, wet clothes should be replaced with dry clothes, if possible, and the casualty should be wrapped in a Blizzard Survival Blanket.”

Hypothermia in trauma cases occurs regardless of ambient temperature, PHTLS says, and prevention is far easier than correcting it: so stopping heat loss should begin as soon as possible after wounding.

The guide places the Blizzard Survival Blanket first in a ‘hierarchical equipment list for prevention and treatment of hypothermia'."

I think your right about opinions varying. I think the new system the RAF mountain rescue has developed is that they recognise that most victims on UK mountains are not completely wetted through and that on balance the clothing the casaulty is wearing will help in reducing the heat loss in addition to the Blizzard Survival bag being employed. (I suspect most casualties are generally winter casualties who generally wear good to high specification wind and waterproof breathable clothing) Further unnecessary cooling when removing the clothing would be painful (due to the windchill) and unnecessary timely for the casualty when they are now realistically within a few hours away from Hospital Treatment. This does make sense.

The casualty who has been recovered from the water will be completely wetted though (unless in a dry suit) and in this case will be out of the wind i.e inside the covered life raft. Recovery of the casualty by SAR may take many days. Getting the hypothermia casualty out of the wet clothing as soon as physically possible and into dry insulating clothing and then the Blizzard Tube would dramatically reduce the heat loss from the casualty.

The new Hypothermia Prevention and Management Kit™ (HPMK NSN# 6515-01-532-8056) looks good. Again the chemical heatpack maybe a no go for the liferaft application and maybe to bulky and heavy for this application. There appears to be no easy answers for this problem. Crew survival training looks likely to be a very important factor.

Yep ! that's about the only usage I ever found for these chem lights !!

I used to keep a bunch of chem lights in various kits, including hiking and car kits.
9 times out of 10, they were dead when I needed them, even when expiration date was not reached !
No way to know if they are still good or not ; you have to try them and find out !
(when you try them, they usually works ! But when you really need one... bad luck ! They are all dead)

If you want lights in that range of brightness, KRILL lights are OK (use them with Lithium AA batteries).
Just be sure not to store the batteries inside the lights : the weight of the batteries + various "shock testing" while stored, will deform internal parts and the light will no longer be useable.


YMMV + IMHO ...

Most of the PLB designs I've seen look like they'd have a pretty low risk of accidental activation. And if you're going down... odds are, someone knows where you are. We generally don't lose ships to bad weather any more. But tactical considerations were something I was leaving out, for that reason.

I probably shouldn't ask, but how rough of weather is needed to sink a life raft? Either the 25- or 50-man variety. Has anyone tried to "gather the flock" as it were under weather, say, 80% as bad? Although, based on the size, once the weather cleared out, they should be spotable from satellite and high altitude air. Not much in nature is that color orange.