What determines drownings after an ocean sinking?
July 5, 2012 6:54 AM   Subscribe

I read today of a capsized yacht that killed over two dozen people, and I realized that I think I may over-estimate my ability to survive a sinking. I have always thought that I could tread water or float on my back for a long time if that were to ever happen, but the fact that people generally drown and sometimes soon after the sinking makes me think that there's a lot of complex things happening during the sinking (and I am probably over-estimating how much energy it would require for me to keep swimming). What is ordinarily the causes of drownings in sinkings at sea?

Has anyone ever conducted survival analysis to determine the proximate risk factors that determine the speed at which individuals will perish in the event of a sinking, and if so, what generally is known about such events? Is it psychological things like "keeping your head"? Is age, gender, etc.? Does it have to do with water temperature, debris, etc.? And can you explain the experience of these sinking scenarios if you understand it well enough so that I understand better what is likely happening to individuals floating in the water as they move through the duration of time where they are at risk? I would appreciate it -- if only so that I could update my beliefs and not be so over-confident.
posted by scunning to Science & Nature (35 answers total) 19 users marked this as a favorite
People who happen to be below decks may not find a way out of the disorienting upside-down jumble in the minute or so that they can hold their breath. Not everyone who gets on a boat can swim, or swim well. Swimming is extremely taxing if you're wearing clothes. Cold water can make it difficult to move or control breathing.
posted by jon1270 at 7:02 AM on July 5, 2012

You may be trapped inside the ship as it sinks, or injured or knocked unconscious before leaving the vessel. The cold water can put you into shock, which can stop from you being able to swim.
posted by mkb at 7:03 AM on July 5, 2012

I'd imagine that being drunk would increase your risk of death as well.
posted by procrastination at 7:04 AM on July 5, 2012 [1 favorite]

You might find this page about drowning useful.

The key points:
Drowning people cannot wave for help. Nature instinctively forces them to extend their arms laterally and press down on the water’s surface. Pressing down on the surface of the water, permits drowning people to leverage their bodies so they can lift their mouths out of the water to breathe.
Throughout the Instinctive Drowning Response, drowning people cannot voluntarily control their arm movements. Physiologically, drowning people who are struggling on the surface of the water cannot stop drowning and perform voluntary movements such as waving for help, moving toward a rescuer, or reaching out for a piece of rescue equipment.
From beginning to end of the Instinctive Drowning Response people’s bodies remain upright in the water, with no evidence of a supporting kick. Unless rescued by a trained lifeguard, these drowning people can only struggle on the surface of the water from 20 to 60 seconds before submersion occurs.
posted by lollusc at 7:05 AM on July 5, 2012 [16 favorites]

Wear a life jacket when out on the water at all times. The ocean is colder than you think and the waves will tire you out faster than you think.

You might find the books Deep Survival and The Unthinkable: Who Survives When Disaster Strikes - And Why. In disasters in general, who survives depends on who keeps their wits about them and can react appropriately, and whose finds themselves stunned/freaked out by circumstances and ends up a statistic.
posted by Pirate-Bartender-Zombie-Monkey at 7:06 AM on July 5, 2012 [6 favorites]

The ocean is cold, you're wearing clothes which weigh you down, and the ocean is choppy -- these factors combine to make it harder to tread water at sea than, say, in a pool. I also suspect that if you lose your boat, there's going to be a big burst of adrenaline and you're likely to tread water too hard and burn through energy quickly (like running too fast early in a long distance race).
posted by J. Wilson at 7:06 AM on July 5, 2012

There's also hypothermia. If your body is burning a lot of energy to try to keep your core temperature at 98.6 °F, you'll get exhausted a lot quicker; and if you're not conscious, you can't tread water or float as easily. Note that according to the chart, the water has to be in the 80+ °F range for you to remain conscious "indefinitely" — which does happen in the Gulf of Mexico or the South Atlantic coast of the U.S. this time of year, but which is less likely in the mid-Atlantic, questionable in New England, and pretty much unheard of on the West Coast.
posted by Johnny Assay at 7:10 AM on July 5, 2012 [3 favorites]

Water temperature is a huge factor. So is having a floatation device. In sufficiently warm water with a floatation device, you can live for days until you die of thirst - see the sinking of the USS Indianapolis, where men survived in the water for more than 3 days. Another factor over that long a period in the water is that your skin starts to peel off.

Without a floatation device, even if you normally float in water, you're not floating on the surface of a still calm pool - there are waves and ripples and things that will require you to expend conscious effort to keep your head above water. Mess up and suddenly you're drowning.

trivia: Quint is totally wrong in Jaws - the Indianapolis did send distress calls. They just got ignored.
posted by rmd1023 at 7:13 AM on July 5, 2012 [5 favorites]

I have no firsthand experience with it, but I read about this technique to remain floating with minimal effort. http://www.drownproofing.com/
posted by cali59 at 7:24 AM on July 5, 2012 [1 favorite]

Response by poster: rmd1023, we watched Jaws a few nights ago and I bet that this question was partly caused by that, as I made a point to my 10-year-old son that Quint was telling a true story.

I didn't realize, though, that your skin starts to peel off if you're in the water for a long period. Why does that happen, and how long are we talking about? That seems incredibly painful -- is there blood?
posted by scunning at 7:28 AM on July 5, 2012

Best answer: These are all important factors - hypothermia can not be overstated. I once had to pull someone out of the water on Memorial Day weekend in Casco Bay, ME. A beautiful sunny day, probably 80 degrees air temp. He tried to swim out to our sailboat from a dock. It was only maybe 25 yards and he was a good swimmer, but the water temp had not yet reached 50 degrees and very soon he could no longer move his limbs.

Had he come off a vessel that went down, he'd have been fucked. Fortunately we got to him in time, though he spent the rest of the weekend wrapped in a blanket drinking hot tea and having his extremities rubbed into warmth again.

Exposure/dehydration are important factors if rescue isn't immanent and particularly in warm waters. Without any protection from the sun, and no fresh water available, you can quickly begin to suffer the effects of dehydration - pain, disorientation, dizziness, sunstroke as well as blistering sunburn.
posted by Miko at 7:29 AM on July 5, 2012 [6 favorites]

Oh, also becoming entangled in the broken equipment from a wreck is a hazard, particularly on sailboats where lines, spars and sails may come loose.
posted by Miko at 7:29 AM on July 5, 2012

Response by poster: rmd1023 -- just saw your second paragraph. Got distracted by the Jaws comment. That makes a lot of sense. There's a ton of random noise in the movement of the waves, and you're at the water's surface. I suspect, too, that sinkings are highly correlated with ocean storms too -- something caused the ship to sink, after all. If water is randomly splashed into your face at regular intervals, then I can imagine that that will set off the chain reaction that leads to a drowning.
posted by scunning at 7:31 AM on July 5, 2012 [1 favorite]

Another factor: Some people can't actually float. My wife, for example, sinks like a stone if she's not swimming, treading water, or otherwise exerting effort to keep herself above water. Didn't believe it until I saw it myself.
posted by Ghostride The Whip at 7:31 AM on July 5, 2012 [1 favorite]

Response by poster: Miko - wow. That's an incredibly dramatic explanation of how soon hypothermia can set in. I had no idea it could be that instantaneous.
posted by scunning at 7:32 AM on July 5, 2012

There also can be a fairly significant burp/bubble when boats go down. If you could survive all the rest, you could very easily get dragged down by an undertow or gonked on the head by some piece of boat when it goes under.
posted by gjc at 7:38 AM on July 5, 2012 [1 favorite]

Also, boats don't generally capsize in good weather. If it's windy and rough enough to cause a capsize or other sinking event, then it's more like trying to stay afloat in whitewater than in a lake or calm ocean.

The amount of effort to keep afloat if you're constantly being submerged by waves is way higher, in addition to the hypothermia and debris issues mentioned above. Also relevant is whether or not you entered the water injured and/or unconscious as a result of the capsize.

So you're probably right that you have a decent shot of mid-term survival if:
1) the water isn't cold
2) the water is relatively calm
3) you entered the water in a non-violent enough way that you're not injured or unconscious.

It's not that common that boats capsize or sink in those circumstances, but when they do, you usually do see higher survival rates.
posted by mercredi at 7:39 AM on July 5, 2012 [1 favorite]

I read about this technique to remain floating with minimal effort.

I had to do a little of that once, I think to earn a scouting merit badge. The requirement was to do that float for about half an hour. It was really hard to calm myself down enough to relax and hang there in the water without kicking to keep my head up all the time. After several minutes of struggling, I did fall into a rhythm and started resting and breathing so automatically that I did several extra minutes because the guy at the edge of the pool couldn't get my attention. But this was in a pool in the summertime -- warm enough, no waves, help just a few yards away. I don't think it would work for very long in more adverse conditions.
posted by jon1270 at 7:40 AM on July 5, 2012

Best answer: I totally believe Miko's story. I was taught during my WEMT training that in very cold water, a person will lose consciousness in about three minutes and there's really no way of stopping it.

I also remember being taught waaaay back in swimming lessons that people can usually only tread water for a couple of hours at most before exhausting themselves. If you float on your back or your stomach then you can last a lot longer, but if the water is choppy (which it probably is if it's the ocean, especially if your boat just sank -- that tends to happen more during bad weather) then you'll probably still wear yourself out just from trying to breathe because you'll be getting water in your face constantly.

All this is assuming that you are able to get clear of the boat and its rigging, that you aren't somehow injured during the sinking (perhaps by a flying object if the boat crashed and/or rolled over), and that you hit the water rested and alert rather than tired and/or intoxicated. If any of those factors are in play then you'll last a much shorter time.

The thing that makes the biggest difference here is a life jacket. Even if you hit freezing cold water and pass out, a good life jacket will hold your head above water. Even if you're unconscious, or injured, or exhausted you will probably still survive for a while as long as your head is above water and you are breathing – so if rescuers come to your aid, you might still survive.

The moral of this story is: wear your damn life jacket.
posted by Scientist at 7:43 AM on July 5, 2012 [14 favorites]

There's a chart showing exposure time vs. water temperature before hypothermia sets in. I can't find it but this wikipedia article lists one data point that should give you an idea, "A water temperature of 10 °C (50 °F) often leads to death in one hour".

Oh, I found the chart. It's in 1997.
posted by chairface at 7:54 AM on July 5, 2012 [2 favorites]

According to this survival manual, life expectancy vs. water temperature:

60 - 70 deg F: 12 hours
60 - 50 deg F: 6 hours
50 - 40 deg F: 1 hour
40 deg F and below: less than 1 hour.
posted by Comrade_robot at 7:56 AM on July 5, 2012 [3 favorites]

Yeah, it was a vivid illustration. I've never forgotten the lesson. It also made me incredibly grateful to have learned a man overboard drill which is how we got to him - so if you're a sailor, in addition to wearing your PFD, learn and practice that drill, and be sure you have a boathook or some other reaching pole and a lifering handy in the cockpit all the time.
posted by Miko at 8:01 AM on July 5, 2012 [2 favorites]

Why does that happen, and how long are we talking about? That seems incredibly painful -- is there blood?

The Discovery Channel has this sea survival page which talks a little bit about the salt water/skin thing. Basically any small skin break becomes a blistered wound which then gets more irritated by the sea water. And this is if you're in a raft and not in the water. Basically salt water will suck the moisture out of your skin and this leads to cracking which then leads to sores that don't heal. So, less blood and more blistering, but it's awful and itchy and very hard to treat if you don't have fresh water.
posted by jessamyn at 8:04 AM on July 5, 2012 [2 favorites]

Read this page about the PS General Slocum, a steamboat that went down in 1904 that took over a thousand people down with it. It's considered a major disaster because of the astounding and largely preventable loss of life.

There are so many little things that can go wrong that will keep someone from surviving, and sometimes several (or many!) go wrong at once.
posted by hermitosis at 8:40 AM on July 5, 2012 [1 favorite]

This article about a father & son lost at sea is like a list of Bad Ocean Choices, but it also has details about some of the physical problems about being in the water (jellyfish aiieee!)
posted by nicebookrack at 8:45 AM on July 5, 2012 [2 favorites]

Like jon1270 I have a little experience with this scenario, due to training in Boy Scouts for the Lifesaving merit badge. If you're wearing street clothes on deck and suddenly find yourself in the water, the weight of your water-soaked clothes is gonna take you down, maybe even if you're wearing a life jacket. So kicking off your shoes immediately and getting out of your clothes can make a big difference, but doing that once you're in the water can be incredibly difficult.
posted by Rash at 8:52 AM on July 5, 2012

You ever see that Good Eats episode where Alton Brown looks for the fastest way to thaw out a frozen turkey? In that episode, he shows how running tap water over the turkey thaws it faster than simply leaving it out in the fridge or even in open air, at room temperature.

That process is basically what happens in the ocean. The ocean is a great heat sink, constantly running water over your body that is cooler than your core body temperature. This sucks the heat out of you, and the lower the ocean's temperature, the faster your body is cooled. The hypothermia sets in, you pass out, and then you drown.
posted by Blazecock Pileon at 9:18 AM on July 5, 2012 [1 favorite]

If this is the very recent boat accident you're referring to, you may be somewhat... comforted? if that's possible here? to hear that only 3 people died, not all 27. The 3 who died were all kids, and two were stuck inside the boat when it capsized. It's a horrible, horrible tragedy, but not everybody who touched the water drowned.

My cold-water experience, like Miko, is in Casco Bay, ME. I've swum in the freezing cold water every year of my life and I am very respectful and cautious about how quickly you can become helpless in that kind of cold. I was just there this past weekend and the water was a balmy 61, which still feels REAALLLLLLLY cold. Even at 60 degrees, I always make sure that everybody in my group does not jump in at the same time, in case a rescue is necessary.

One tip: when you fall in to very cold water, even if it's on purpose, it's often very hard to avoid gasping. Sometimes it becomes hard to breathe for a few seconds. If you can be aware of this, you can avoid snorting in lots of freezing water (guaranteed to make you colder, faster, and to make you feel sick) or panicking because you can't breathe. Just give your body a few seconds. I have been SCUBA diving in 40 degree water - in the thickest possible wetsuit of course - and I think the hardest part was taking my mask off and having the icy water hit my face without sucking in water involuntarily.

RE: life jackets: your life jacket needs to be fastened such that you can be hauled out by the back of the jacket without slipping through. If it's too loose, or it just fits improperly, rescuers will not be able to haul you in to a boat by grabbing the jacket. Also, if you are wearing heavy sodden clothes, you could slip through the jacket and drown if you lose consciousness.
posted by Cygnet at 9:23 AM on July 5, 2012 [2 favorites]

As a longtime surfer and a more recent sailor, these are some observations I have:

Boats aren't likely to capsize in good weather conditions, they capsize in stormy conditions. When it's stormy, there are waves, and not just big waves, but little choppy waves that occur very frequently (often more frequently than 1 per second) and if they hit you in the face while you're breathing in, they will make you choke and gag.

Swimming through waves is *extremely* tiring, especially if you're not accustomed to doing it. A typical problem for beginning surfers is that they can't get their board from the beach out to where surfers sit to catch waves (which is just farther out than where they break). This is partly because they lack the arm strength that you get from spending a lot of time paddling, and partly because they lack the technique for diving under a wave and coming up on the other side with a minimum of effort and a minimum of lost ground. I have watched plenty of people wash up on the beach completely exhausted from this after as little as 20 minutes. Swimming in waves is hard.

Having to do any of these things in cold water makes it harder. You tire faster, your muscles get sore, you can't hold your breath as long.

If you fall off a boat at night, you're largely screwed if you don't have a strobe light on you. You're nearly impossible to see or find. When I was taking sailing classes we did nighttime man-overboard drills (with a strobe light on our dummy) and it is sobering. The speed at which a sailboat, which normally seems slow (they really only go 6 or 8 mph most of the time) moves away from that dummy, to the point where it becomes hard to see, is sobering.
posted by tylerkaraszewski at 9:31 AM on July 5, 2012 [2 favorites]

To the early comments about the symptoms of drowning: I was a professional whitewater guide for a while. For the first year or two, my reflexes tried to make me breathe in when I got tossed in the water. When that happened, I was then unable to synchronize my breathing with the waves, and I got into this cycle of trying to breathe, getting a mouthful of water, going under, surfacing, repeat, yuck.

After I learned to override that reflex, whitewater became a lot easier: I could swim many rapids, if I got thrown out of the boat I had the chance to go under waves, strategize, oxygen was no longer my immediate and primary and instinctive concern.

It's been a decade and a half since I've seriously paddled, and I'm no longer sure that I can override that reflex. I'm especially no longer sure that I could do it if the water were seriously cold. So long before hypothermia became an issue, I can imagine that if there are whitecaps I could drown if I were tossed into the ocean unexpectedly, or in circumstances where I was distracted with other emergency stuff. Like trying to keep a boat out of trouble.

Mrs. Straw and I recently built a small (12') sailboat and have been working our way up from a tiny lakes. I've been thinking it would be nice to go hit Richardson Bay or Tomales Bay, relatively sheltered water, shouldn't be a problem, but my extensive whitewater experience means cold saltwater without a wet suit or dry suit (let alone just a PFD) scares the living crap out of me.
posted by straw at 10:14 AM on July 5, 2012

kicking off your shoes immediately and getting out of your clothes can make a big difference

Oh, just remembering now when I taught swim and we taught how to do this and also use your taken-off clothes to make a bouyancy device. It sounds ridiculous but it sort of works - better than no device, anyway. Kids had to pass this at the senior swim level. But see above about the sun: if you're out in beating sun you might rather keep your skin covered.
posted by Miko at 10:20 AM on July 5, 2012

If we're talking about the same yacht, in Oyster Bay (Long Island Sound), then it didn't kill two dozen people-- 3 children died out of 27 people total aboard the (IMO) dangerously overloaded yacht.

You might be interested in the WWII sinkings of the USS Indianapolis (which carried one of the Atomic bombs to Tinian, from where it was delivered to Japan) and which was nearly sunk on the way to Tinian (resulting in a very regretful Japanese captain) but was sunk in the way home, and about half the crew was in the water, slowly picked off by the elements, the sharks, some injuries and such, and their own psychologies.

Another episode in WWII was the USS Samuel B. Roberts, which was mortally wounded after some absolutely heroic fighting in the Battle Off Samar, which was the second major engagement in the Battle of Leyte Gulf (West coast of the Phillipines, off Samar Island).

In both cases the South Pacific sea was favorable for longish-term human survival-- Roberts sailors were rescued on the third day, but it was also home to sharks, and the crews dispersed for general lack of energy to stay together.

The Indy was torpedoed, while the Roberts had been shot to pieces; in each confusion, nobody knows how many went into the water in each case, but it is known how many are rescued, and generally it's estimated that about 2/3 were lost in each case. The survivors, though, lived to tell their accounts, which are out there in the annals of WWII.
posted by Sunburnt at 2:07 PM on July 5, 2012

Yeah - in this particular case 27 people on a 34 foot sailboat is what went wrong. That part of the sound/Oyster Bay Harbor is quite protected and the water is pretty warm - mid to low 70's.
posted by JPD at 5:22 PM on July 5, 2012 [1 favorite]

This reminds me of a non-obvious-at-first fact. As you all know, our body temp is around 99F, but a comfortable room temperature is more like 72F or 70F, varying with the person. That means that to be comfortable, you desire to be losing heat at the rate one radiates heat in still air at around 70-72. I thought that was interesting. YMMV.

When the temp's higher, we're losing less heat and feet accordingly hot, and when the temp is higher than body temp, such as the 104F hot-tub, we're accumulating heat, potentially to our peril. (It's also known as poaching or braising, depending on how much of your body is out of the water.)

As noted above, convection is the best form of heat-transfer-- it beats conduction and radiation hands-down (and, no thanks to physics, is also the hardest of the 3 to calculate), but even by conduction, water at 72F sucks heat out of your body far faster than air at the same temperature (air being an insulator). Hence, why room-temp water makes a cool bath, and a comfortable bath is somewhere in the 80s. And also why you can safely reach your hand into an oven where the air-temp is 500F.
posted by Sunburnt at 6:01 PM on July 6, 2012 [3 favorites]

air being an insulator

And/or water being an awesome, dense conductor.
posted by Miko at 6:38 PM on July 6, 2012 [1 favorite]

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