Cold Water Survival

The first few seconds can be the most dangerous.


When we read about a sailor lost overboard in a storm, we think about PFDs and personal locator beacons, and accept the sea is unforgiving. When we read of novice boaters drowning in a local lake, we’re sad, but say that will not happen to us because we wear PFDs. But when we read of a PFD-equipped sailor falling overboard and dying within minutes, it’s a real eye-opener.

Spring sailing in temperate climates still carries the risk of cold water shock. With the water temperature in the low 50s, true hypothermia sets in at about 30 minutes. Swimming can be difficult after about 20 minutes. However, 50 degrees is well below the accepted threshold of shock. Most likely, when the icy water slams into a person’s face it causes an involuntary gasp. It’s hard to recover from inhaling water, even for a strong swimmer.

Originally known as sudden disappearance syndrome, cold water shock has been known since the 1970s. Different from true hypothermia, which results from the body core temperature dropping over a period of 20 minutes to hours, cold water shock is immediate. Being cast headfirst into icy water is one of most severe shocks a human can face, with deadly effects. It is estimated that 20 percent of victims die within 2 minutes.

Physical effects

The instantaneous reflex is a violent gasp, totally unlike the one scary movies strive to cause. This results in a massive in rush of air, which can be fatal if you are underwater. Unlike the controlled plunges of the local polar bear club, where participants walk in via a beach and are attended by rescue swimmers in dry suits, MOB sailors plunge in head first, the result of tripping over the lifeline. Even with an automatic vest, your head will plunge 6 feet underwater before popping to the surface. If the first blast of inhaled water doesn’t drown you, you’ll arrive on the surface gasping and unable to swim and swallowing more. Drowning will typically occur in less than a minute. The initial gasp is followed by several minutes of hyperventilation, making any physical effort nearly impossible. Consequences include the inability to hold your breath or think clearly.

Instantaneous and massive increases in heart rate and blood pressure can cause heart failure in otherwise healthy individuals. Clear thought is impossible. Panic is likely, only serving to increase problems with breathing control and heart rate.

These reactions may appear to an observer as nothing more than panic. Flailing, spastic breathing, muddled thinking, and a racing heart fit the pattern. But victims include experienced sailors and strong swimmers who are not at all prone to panic. If you fall overboard in warm water and reasonable weather, your first concern might be embarrassment over screwing up the race, and later whether the boat would be back in the next half or hour so. It wouldn’t have felt life threatening.

If you survive the first critical seconds, then come the more traditional challenges of cold water exposure. Cold incapacitation and swimming failure begins in 5-20 minutes, the result of failed muscle control. In the absence of a PFD, drowning follows. Death from true hypothermia (cold core) takes considerably longer, at least 30 minutes in very cold water up to a few hours in cool water.

How do you keep this from happening to you? First, don’t fall in. The first line of defense is careful movement and the use of harness and tether systems as described in PS October 2018. If sailing a smaller boat, prone to capsize or swamping, dress for full water immersion. In cool water either a thin wetsuit or dry suit is effective. Once the water temperature drops below about 50F, only a dry suit is suitable. (See PS November 2018 and March 2009.)

If performing high risk activities on larger boats (hiking out, working on the bow, or leaning outboard) a dry suit is the smart option. It is our favorite foul weather gear for stormy conditions in cool weather; more agile than heavy foul weather gear and nary a drop of water will go down your neck. Small wonder is increased in popularity with offshore racers and sailors.

Unfortunately, once the air temperature gets above about 55F, dry suits get steamy, tempting the wearer to open the zipper and defeating the whole purpose. As the water temperature rises into the 50s, we like paddling jackets and dinghy smocks, with snug fitting wrist, neck, and waist seals. Water will sneak in pretty quickly, but shock is reduced and the seals reduce the exchange of cold water. The wearer is also more mobile than in conventional foul weather gear.

Soft shells may also have possibilities. Once our tester found himself in 35F water, with ice around the edges. He was dressed not in foul weather gear or dry suit, but in Wind Blocker fleece tops and bottoms. The saving factors were that the wrist, waist, ankle, and neck closures were all tightly secured; not all soft shells have effective closures. Although very cold, it was more survivable than ordinary foul weather gear.


The last 12 months have been hard on ocean racers. It is more than coincidence cool or cold water was a common factor. In the UK, coldwater shock is considered to be the root cause of most drowning, including non-boating accidents.

We like certain features of manual inflating PFDs; they don’t go off inadvertently and climbing back aboard is easier. But cold water is different. Because of the high probability the wearer will be incapable of action for a minute or more, auto-inflation is the way to go.

We would like to see the makers of foul weather gear take a long hard look at what can be done to improve cold water shock resistance. Conventional jackets and soft shells could be fitted with effective internal neck seals. Wrist and waist seals could be upgraded.

We would like to see race committees post cold water warnings. It is common to require PFDs be worn above a certain wind speed. The race committee should at least recommend that protective gear such as a wet suit or drysuit be worn if the water temperature is below about 55 F. Our level of caution around the rail varies with the risk we perceive, and that level of caution goes way up when the water temperatures go down.

Most importantly, sailors need understand what being thrown face first into cold water feels like and how their body will respond to it. A diehard for traditional foul weather gear? Don’t fall off the boat in cold water, and don’t expect to survive more than a few minutes if you do. Its tough out there.

Tips & Technique
Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him by email at


  1. While I agree with the safety concerns in the article the author is misleading readers when he says Jon “disappeared almost immediately”.
    Here’s what is in the Chicago Yacht Club incident report –
    “On July 21, 2018, at approximately 14:26 CDT, Jon Santarelli, slipped overboard from the cockpit of the TP 52, Imedi, as she sailed northeast from the 14:00 start of the Race to Mackinac. The Imedi crew immediately tacked and circled back to Jon’s position in the water, never losing visual track of him, but were unable to stop the boat close enough to retrieve Jon, due to the 20-25 knot winds and 6-8’ seas. They circled again and came closer to Jon on the second attempt, this time with the engine running, but just as they got close to Jon, a wave forced the boat up and over Jon and he went under the boat from starboard to port. Imedi circled a third time, and this time they were able to stop the boat very close to Jon, but as they tossed Jon a line and he raised his arms, he sank below the water and was not seen again. His life jacket, which was reported as set for automatic inflation, never inflated and he was never seen to try to manually inflate it.”

    • Thanks for pointing this out. Although this great article is pointing many very important to know aspects of drowning in cold waters, it is also a MOB drill we all practice that plays a role in the recovery of MOB. This tragic incident should always be a reminder to me, and perhaps others, not just to show the inflatable lifejacket and talk about it but also let all crew practice inflate it manually in the water.

    • Thanks for the important reminders on cold water PS.
      A COB method that is not practiced or used enough is the Life Sling method. As a US Sailing instructor sailing out of San Francisco, we would teach and practice COB offshore in 25kts and 8’+ seas fairly regularly. In these conditions of COB we always picked up in the windward side (yes more difficult ) but avoided the vessel being dropped down on top ot the victim when in these conditions. By far the best method in cold rough waters is the Life Sling method. It must be practiced as it is not so easy. You must do a quick tight “ button hook turn very near the victim in order for the line and horseshoe to get to the victim. Manual dexterity not required to get it over your head and shoulders. Once there, you have flotation! (Until you loose consciousness ).
      I also think that vest manufactures need to address the oral inflator. As a Scuba instructor I am very familiar with how BCD inflators work. We need something more along these lines.

  2. Google “Cold Water Boot Camp” and watch at least the half hour version. In Maine in is routinely shown at Safety at Sea training for fishermen at the Fishing Partnership one and two day sessions. Watching it you will learn the 1 10 1 rule: One minute to get your breathing under control, Ten minutes of useful motion with your hands and arms, and 1 hour before death from hypothermia. Of course these times are dependent on the age and condition of the swimmer and the temp of the water. In Maine, in March, the times are likely shorter for most of us.

  3. I take issue with the statement, “Because of the high probability the wearer will be incapable of action for a minute or more, auto-inflation [PFD] is the way to go.” According to the nautical KISS rule [keep it simple, sailor], a conventional foam-filled PFD, which has no mechanism to malfunction or inspect other than the strap buckles or zipper, is better in cold water because its failure rate is essentially zero.

    • The problem with conventional PFD is the fact that it is clumsy and gets in the way of racing the boat. Actually wearing a PFD is a choice. The auto-inflating PFD is very reliable and at least they will be worn. A dingy vest is another option but again on a large yacht it is clumsy.
      Obviously the choice of wearing is up to the captain. However the MOB procedures this yacht undertook directly impacted the success of recovering the crewman.

  4. After your first paragraph, the article imparts great information. Those of us in Chicago remain sensitive about the accuracy of any report on Jon’s tragedy. Don’t use that paragraph in this article when the Mac report says “The water temperature was about 70 degrees …”. Yes, it was a tragedy, yes, we were all then wondering, and given the destruction of the PFD remain wondering, what happened. But it sure doesn’t seem like either cold water shock in 70 degrees, or hypothermia since the skilled sailors were back twice to try recovery, in demanding wind and seas, in less than 15 minutes. I have a personal opinion, after having read the report, but I will discuss it with shipmates, not broadcast publicly.

  5. Correction. The water temperature in the Chicago Mac race was about 70F. This was correct in the initial publication, but the error crept back in. Thus, it was a poor example, and our apologies for this reporting error.

    Nonetheless, the gasp reflex is a common cause of drowning in cold water areas. This January a Baltimore man jumped in to recover a wayward dinghy and just sank.

  6. This is an example of how incompetence kills your crew.
    The Official Report of this MOB had Mr. Santarelli ALIVE during the third attempt to recover him.
    “Review Committee Report on the
    Fatal Accident Involving Imedi
    During the 2018 Chicago Yacht Club Race to Mackinac
    on July 21, 2018
    Published: February 25, 2019”

    The first attempt to recover Mr. Santarelli FAILED because the Captain never started the engine. With the engine powering the yacht the probability of success increases.

    The Royal Yachting Association does not at all teach ANY recovery under sail as they want to stress the importance of recovery by the best means possible and under sail is not the best, unless you do not have an engine. Recovering an MOB is not the time to test your sailing ability; START THE ENGINE and STOP THE BOAT. Maneuver to the lee of the MOB and recover. You can do all these fancy under sail maneuvers but you are likely going to kill your crewman, START THE ENGINE, STOP THE BOAT, MANEUVER AND RECOVER.

    In my opinion the crew of this yacht was incompetent.

    How often do YOU practice MOB recovery with your crew under adverse conditions?

    • “… they got close to Jon, a wave forced the boat up and over Jon and he went under the boat from starboard to port.”

      Hmm. I can’t help thinking that actually running over your MOB isn’t going to help much, PFD, cold water shock or anything else.

    • Don’t forget that exposure of the scalp. accounts for a significant loss of body heat.
      A diver’s neoprene hood that fits snugly around the neck and down the frontal scalp to just above the eyebrows reduces heat loss and also has the potential to reduce the gasp reflex.

  7. Of course the really big question still remains. Why wasn’t Mr. Santarelli tethered to the yacht?

    This is also the responsibility of the Captain. If conditions were so poor to impede an MOB recovery then those conditions should caused the Captain to order his crew to tether themselves to the yacht.

  8. Interesting comments. However, I have had a different experience having done frost biting for years.A simple kayak shirt with water proof cuffs and neck worked fine. Typically able to right the boat after capsize.
    On one occasion having succumbed to my wife’s suggestions I bought a dry suit. Hot as hell when racing. After a capsize where the boat was turtled and the mast was stuck in the mud by the chase boat trying to help I ended up swimming to shore. I was near frozen and only upon getting to shore realized my legs were barely workable. That dry suit did nothing to keep me warm. Dry yes. Incidentally, did you ever try to swim with a PFD on? You can’t at least with the type that holds your head above water.
    Norman Kellershon. JY 15, Centerport, NY

    • A dry suit (properly designed, made, maintained, and donned) will keep you dry. Whether you will be warm depends on what you wear between the cold inner surface of the dry suit and your skin, taking care not to overdress and sweat so much that your inner layers no longer insulate well.

  9. I can’t speak to all manner of life vests, but you can swim in the ones I have tried, not very well of course, but short flipper like pushes with your arms and hands. A little better on your back. Try it!

  10. If you don’t haul out in the fall, the opportunity for cold-weather repairs and modifications remains all season. It is easy to forget the opportunity for misfortune while you’re tied to the dock, where you easily could be alone. For that reason, I have installed a ladder onto the finger pier, with the lowest step far enough down to be nearly vertical and still in the water. A short ladder requires too much arm work, at a time when you are heavy laden with a full suit of wet clothes.

  11. Your basic overview of the Chicago Mac incident is horribly inaccurate. I know people who were on the boat and Jon Santarelli did NOT disappear “almost immediately”. In fact he was floating long enough for his boat to turn and return to try and recover him. There were two main issues with the rescue according to people I talked to:
    1. His life vest did NOT automatically inflate. There was some sort of failure in the mechanism which was NEVER inspected or investigated.
    2. The boat actually ran over him, I believe more than once. The skipper tried to come up on the windward side which would allow the boat to “drift down” onto Santarelli for recovery, but the winds were too strong.
    Had they come up to lee, the outcome may have been different. No one will ever know.

    But, had he been wearing a foam PFD or had the one he was wearing actually inflated, he would not have gone under. However, if he had been wearing a foam PFD or had the PFD inflated, the ability to swim to the boat would have been more difficult. In this situation, 4-5 boats had dropped out of the race to help in the search and recovery. Having an inflated PFD would have allowed more time for rescue.

    Another incident on the Mac a few years ago, a sailor spent 45 minutes or so in the water after falling overboard during a storm in the middle of the night. He was not able to fasten the life vest before falling overboard and the vest light failed after a few minutes. He had to hold the jacket the whole time in the water while he blew his whistle. He was eventually rescued by his own boat because they could hear his whistling.

    And, lastly, water temperature in Lake Michigan is a tricky thing. Most temperatures are given from surface readings. As a life-long sailor on Lake Michigan I can vouch for the fact that the water temperature a few feet below the surface is rarely the same. Falling in from the deck of a sailboat you will plunge at least 5 feet down before coming back to the surface. If the water temperature is 70 degrees at the surface, it could easily be 60 degrees or less 5 feet down. And during a storm, there could be significant turnover and the water 10 feet or more down could easily be 50 degrees or less. I have gone to the beach on one day when temps were 70 or warmer and come back the next when the water was 50. Don’t assume because the weather report tells you the water was 70s degrees that it actually is 5 miles in the lake when you sailing in 15-20 knots of wind.

  12. It’s not just ‘rough’ conditions that are a risk of Man Over Board. In light weather, many take more risks. I carry a cylume torch, wrapped in an orange flag with cord to tie around one’s neck and fit over your wrist for waving, so it can’t be washed or blown away, inside a rigid tube (so it doesn’t break accidentally), and also wear an orange or air sea rescue colored hat, as you loose 1/3 of your body heat through your head, and that’s the most likely way to be seen. A mirror can be aimed through your fingers, from the sun, searchlight, or moon? I tow two lines attached to the tillers, and a block ‘n’ tackle, in case you can? get back to the boat.

    • I suggest you carry a handheld VHF, preferably with GPS and a DSC mayday button. Most boats these days carry a radio. USCG and nearby boats will be alerted to your mayday. Two-way communications allow you to guide a rescuer to you.

  13. This has been said before, many times ; but it obviously needs to be repeated. I don’t care how much fancy safety clothing you wear, the solution is simple. Don’t fall off. I’m a long-time skipper, charter yachts included. My rules (however unpopular) are : You NEVER leave the cockpit without being hooked on. You stay hooked on all the time you are on deck. You may only unhook when lying down on deck in sunny weather, with the skipper’s permission (so he’ll be keeping an eye on you). You NEVER leave the cabin or climb the companion steps until you have ALREADY hooked onto a strong point in the cockpit. You may then unhook (because transit of the steps is a danger point) until heavy weather or the watch captain require you to hook on again in the cockpit. Don’t ever assume that because it’s a nice, sunny day with a perfect sailing breeze, you can’t fall off. It can and does happen at any time, for too many reasons to list here. I know that yachting associations and magazines love to revel in advice about what to do if you fall off, and recovery techniques. Understand that, if you fall off, your average chance of rescue is tiny. So it’s simple ; DON’T FALL OFF !
    Happy safe sailing everyone.

  14. I bought a Mustang Anti-Exposure Coverall many years ago. I have worn it when sailing and fishing on Lake Erie, Late Ontario, the Niagara River, the Atlantic Ocean, and the Gulf of Mexico. I wear it when the water temperature is below 68 degrees or in situations were we will be sailing or fishing with the air temperature below 60 degrees. The Coverall has reflective strips, insulation, a hood, and an inflatable pillow to keep your head out of the water. It is colored orange. In my experience it is it warm and comfortable to wear in cold situations. A negative is that it is bulky to store and costs around $475. I add an inflatable life jacket with a built in harness and a light and whistle. I have worn it about 200 days. 5-stars.

    • I’ve had an anti-exposure coverall for about 18 years, absolutely love it. Usually comfortable and warm! Yes a little bulky, yes a little sweaty at times, but if I go overboard in our pacific 50-55 degree water, it gives me 3-5 hours at the least for recovery by an often inexperienced crew. My one accidental overboard when maneuvering, no cold shock, swam to the stern, climbed back on. Use lifelines too.

  15. In the 1980s and 90s I fished a 1915 28’ Monterey, later a 32’ commercial rigged cutter, trolling for salmon on the North Pacific coast. Like most of the fleet around me, I was a sole practitioner – no one on the boat to turn around and rescue me [or run me down in the effort!] if I fell over. A common vision occurred to me as the boat rolled along on auto-pilot was …The boat mounted on a large coil spring on top of the Empire State Building, bobbing and swaying in the wind. A fall overboard would most likely have the same outcome.

  16. The breathing reflex when hitting cold water is hard to control. I’ve done some triathlons in Santa Cruz, CA in cold water and it hit me hard. Now that I know what to expect, I am okay. I suggest sailors in cold water areas go to the beach and jump in and experience it first hand. That will help a lot if/when it happens by accident.

  17. Mr. Kilgus offers salient advice. Wade in the first time, then dunk your head under for a few seconds. After a couple of those, dive in and stay under a few moments longer. This conditions the mind to a cold immersion event and with some practice one should not gasp. In my case I run Grand Canyon solo on a raft and the water starts out at 42.5F and ends 300 miles later at about 50F. If daytime air temps go below 70F I don a drysuit. Throughout the trip I dive into that ice water from time to time, making it much easier to defeat the normal reaction to gasp. When sailing through cold water I typically dive in in the morning when anchored/moored, take a hot shower and get on with my day. My neighbors think me crazy, well not really, but most won’t do it. If you’re going to sail in it you should be able to swim in it. I know, it sounds a little harsh, but so is drowning.


  19. I used to rock climb, a lot of it in Yosemite. My view is that going on deck (or standing in the cockpit) without being tethered is like climbing without a rope. If there’s any boat motion at all, and especially when the water is cold, I tether. And I always keep a hand hold–going over even tethered also has fairly grim probabilities. And it takes some experience to learn how to work with the tether(s), so doing it “unnecessarily” is actually good practice.

  20. I recommend trying out your auto or manual CO2 charged lifevest. It inflates so powerfully that it constricts my chest and makes it hard to breathe. Finding the release valve was the second problem. It is hidden high up almost under my chin with strong adherent velcro that is hard to separate. I prefer my old foam vest.

  21. Best article / comment combination I’ve ever read I .
    Keep up the good work ! Especially like the example of rock climbing.
    I have a pad eye on the bridge deck to clip onto – right at the companionway – it’s easy to clip on while standing in the galley, and the tether is long enough for any cockpit activity. The tag line runs from cockpit to cabin front and the tether reaches to the bow .
    I will confess that I fished salmon commercially off N.W coast of Vancouver island in the 70’s – never clipped in, but railings etc were (almost)continuous at waist height from wheelhouse to fishing cockpit aft.

  22. I have done 4 Transpacs, the last 2 mandated crotch straps on the inflatable PFDs. Rule on board was simple , if you are on deck, you harness and tether, up, no exceptions. Many sail changes between 2 and 4 a.m., due to increased wind and waves. A number of close calls over the years but Never a COB.
    Wear your proper gear and you will sail again .