Is grease an aid to survival in extremely cold water?

Rough question: Does applying grease to your body before going into lethally cold water, as in a ship sinking in the North Atlantic Ocean in Winter, actually give you any survival advantage?

1.) I have read several separate accounts by survivors of torpedoed ships in the Atlantic Ocean during WW II in which prior to going into the water the victim applied some sort of grease to his body (type unspecified) in the belief that it would hold-in heat and increase his chance of survival. Each swore this had saved his life.

2.) In researching this online, I find conflicting information. The technique seems to relate to long distance swimming, such as the English Channel. Some experts say the right kind of grease (lanolin or vaseline), or the right mix of these, and careful application to particular areas of the body, is of benefit for distance swimmers in cold water. Others say, all in all, it is more trouble than it is worth, giving little or no advantage, and, improperly done, is a distinct detriment.

3.) The only explanation having to do with preserving core body heat said this: That the body NEEDS the shock of cold water to close off the vascular system in the extremities (arms and legs) in order that the vital core of the body (trunk) will hold in the heat it has longer, increasing the time you can function (or survive) in cold water. Grease will prevent this closing off of the extremities, making loss of heat from the body core happen more quickly.

My Question:

Is there any survival advantage for a sailor spreading some type of available grease on any portion of his body prior to leaving a sinking ship in an extreme cold water environment, such as the North Atlantic in Winter or the icy Barents Sea on the run to Russia?

If they have enough time to spread grease all over their body, I’d think they would be better off getting into a lifeboat, and carrying extra blankets, water, & food, not grease.

Well, then just put the grease only on the trunk, and leave it off of the extremities!

Goose grease (favoured by Delia Smith for great roast spuds) is apparently the grease of choice for Channel swimmers. I thought the purpose was more about preventing chafing (thighs and flanks) and skin breakdown due to longterm immersion than temperature.


I’m not a channel swimmer or medical expert, but I highly doubt that for icy water there’s any benefit. In 4 C cold water, your normal survival time is in the area of 5 minutes! Even special survival gear clothing can’t extend it much beyond 15 or 20 min.
Channel swimmers definitly have warmer water (they choose their date carefully for a reason), and they have support (usually a boat nearby) plus food to get energy from.

I remember several years back, there was a joint NATO marine exercise in the North Sea/ Baltic Sea. It was not even freezing temp., but actually a bit above, yet when a sailor fell overboard, although he was pulled out as quickly as possible and airlifted to a hospital on the land, he died from hypothermia. It was a bit over 5 min., but below 10 min., the time necessary to get him out.

Anything that provides insulation is going to help with survival time in cold water. Not sure how effective it would be, but I’d expect it to be significantly useful.

I don’t think so, otherwise why did they apply grease to their entire bodies? Preventing chafing may have been a side-benefit.

The final advantage is, if you get eaten by a shark on your cross-channel swin, at least you have caused it’s arteries to harden.

No way you can apply grease in a layer thick enough to reduce heat transfer rate by any useful amount. The thermal conductivity of fats/oils/greases is in the same range as human tissues. Conductivities (W/(m*K))from my heat transfer text book:

human fat, 0.2
human skin, 0.37
human muscle, 0.41
engine oil, 0.15
paraffin, 0.24

It’s reasonable to assume that other oils/fats have conductivities on par with human fat, engine oil, and/or paraffin.

Assuming your skin is a tenth of an inch thick, slicking yourself with a layer of grease/oil a few thousandths of an inch thick (i.e. enough to make you slippery) adds negligible thermal resistance. Even globbing extremely viscous grease on, you’re probably not going to retain a layer more than a tenth of an inch thick, and the grease itself isn’t a good choice of material for insulation. Consider that survival suits that cover everything but your face are 0.2 inches thick, and made of neoprene foam that has a thermal conductivity of 0.055. Assuming some random grease that has a thermal conductivity about equal to paraffin, a layer of that grease a tenth of an inch thick (assuming you could cover your entire body with that thickness) will provide only 11% of the insulating value of a survival suit. And good luck covering your entire body with a tenth of an inch of grease while the ship is sinking.

As others have reported, I think endurance swimmers use skin lubricants for the same reason that triathletes do: to prevent their limbs from being rubbed raw by hours and hours of repetitive movement.

Well try factoring in 10 to 15 pounds of grease as most channel swimmers seem to use.

Typical human bean has a skin area of about 20 square feet. Cover all of that with 0.1 inches of grease, and you’re talking about 0.166 cubic feet of grease. oils and greases typically have a density of about 55 pounds per cubic foot, which means we’re dealing with 9.16 pounds of it.

I don’t believe distance swimmers are applying a tenth of an inch of grease to their entire bodies.

From the Channel Swimming Association website FAQ

It seems to me that those who realise that the grease probably does not do much for the cold just use it for chafing reduction. And having done some open-water swimming, it is surprising where you can chafe without realising.

Here is another take on the grease theory - that it reduces convection cooling on areas that get wet but are not completely immersed. It appears that the use of grease is decreasing, and most people now use for reducing the chafing.


I would question that. Seals are a similar size to us, and use layers of fat to insulate themselves very effectively. They can quite happily swim in Arctic waters that would kill us in minutes. In the case of a human slathered in a layer of fat, their skin is in contact with the fat, instead of directly with water, which has a much higher thermal conductivity.

I’m not sure it would be terribly effective, but I suspect it would make an appreciable difference. Your figures show that human fat has half the conductivity of human muscle. You are correct to say grease would be vastly less effective than a survival suit.