The Offshore Voyaging Reference Site

20 Things I Have Learned About Crew Overboard Prevention


Just three years ago I thought I really understood Crew Overboard (COB) Prevention, to the point that I wrote several posts describing our system. And then, as part of that process, I found out just how little I really knew, and how many of my cherished ideas about what would keep me and my crew safe were just plain wrong.

That realization started Phyllis and me on a project to improve our COB gear and procedures.

We are now out sailing, have been testing our new system, and are finally satisfied that we have not only reduced the chances that one of us will be lost overboard, but also come up with a substantial improvement on the standard gear and procedures used by most offshore sailors.

And better still, none of these changes have made us any less efficient in handling our boat; in fact, rather the opposite.

Over the next few months we will be publishing new and updated chapters in our Crew Overboard Prevention Online Book detailing this season’s changes and improvements.

But before we do that, I thought it would be useful to publish a short overview post to get us all back up to speed, particularly since I have not written on this subject in nearly a year, and some of you may not be aware at all of the work we have done on it to date.

I Have Learned That:

  1. The regulations developed for COB prevention by ocean race regulators are deeply flawed, particularly when applied to short-handed cruising crews, and should not be relied on.
  2. The offshore sailing community places far, far too much emphasis on recovering a COB, and not enough on making sure that no one goes overboard in the first place.
  3. The chances of a short-handed crew recovering a COB offshore are way less than 50% and, if it’s blowing hard or dark, approach 0%. Note that every COB recovery practice video is made inshore in smooth water, good visibility, and benign conditions for just this reason—losing people in drills is a bad idea.
  4. Being attached to the boat at all times, without the need to unclip and reclip while performing sail handling functions, is vital.
  5. As several recent tragedies have shown, drowning by being dragged on a tether is a far bigger risk than most sailors realize.
  6. Self-rescue while being dragged is near-impossible.
  7. It is difficult or impossible for a short-handed crew to recover a person being dragged (recent deaths have tragically proved this).
  8. Tether arrest shock loads are far higher than most sailors realize—as  much as a ton or more in comparatively short falls or while being dragged—and can kill or maim.
  9. Most jackline systems are useless and may even be more dangerous than no jacklines at all since they confer a false sense of security.
  10. Low-stretch jacklines made of Spectra or wire are a very bad idea because they increase shock loads, can break due to the geometric load multiplier, and don’t eliminate drag risk.
  11. To be safe, jacklines and tethers must be arranged in such a way that the tether end attached to the crew’s harness can’t get closer than one foot to the toe rail.
  12. Centreline jacklines are the only viable way to solve the above problems.
  13. On our boat (and I suspect most boats) a centreline jackline system can be designed that allows efficient working of the rig while still solving the problems above.
  14. The crotch straps on harnesses and lifejackets sold in the marine market will fail under tether arrest loads and therefore should not be relied on.
  15. It is vital that harnesses have easily adjusted chest straps and that crew learn to always adjust said straps so they are tight after every change of clothing bulk.
  16. Falling as little as 2 feet while attached to a hardpoint with a typical tether can result in chest crushing loads.
  17. Tethers made of high-modulus materials, like those we are now seeing in marine stores, are a very bad idea and potential killers.
  18. Attaching to a jackline is safer than a hard point because deflection of the jackline reduces impact load.
  19. Tethers that will be attached to hard points should be made of high-stretch materials.
  20. In the quest to reduce the risk of a COB tragedy, an open logical mind free from the dogma of “we have always done it this way” is our most important asset.

Wow, quite a list. I’m guessing that many of you who were not part of our three-year project to learn the above are shaking your heads and assuming that I’m some kind of cracked safety nut.

In fact, you are probably ready to close your browser window and go read about something fun. I don’t blame you. Three years ago I would have left too. But if you care about your own safety and that of your loved ones, don’t.

I didn’t make this stuff up, rather it is the result of the combined wisdom of voyagers, engineers and climbers expressed in hundreds of comments to my earlier posts on the subject. A huge thank you to all of you who contributed.

Phyllis and I then took that information and spent hundreds of hours thinking and experimenting before coming up with a better system.

If you are new to this project:

I strongly suggest you start at chapter one and read through to the end. Yea, I know, you are busy. Fine, but are you comfortable saying that “I don’t have less than an hour (that’s all it will take) to invest in my loved ones’ safety?” No, didn’t think so.

If you were part of the project from the beginning or came in at some later point:

I suggest you read through the Online Book Table of Contents to make sure you are up to speed on all the above points.


I considered publishing this post with the comments closed because I dread spending hours covering subjects that we have already done to death. In the end I decided not to take that path. Please confirm that I made the right decision by at least scanning the contents of the Online Book and reading the relevant chapter before commenting to make sure we have not already covered the subject of your comment.

Please Share

One more thing. This is important stuff, please share this post by using the social buttons below, it really helps get the word out.

And if you are thinking that you won’t share because this post links to paid content, ask yourself  these questions.

Do you never recommend:

  • a restaurant because the food is not free;
  • a book because it costs money to buy;
  • a movie because it is not free;
  • a great boat mechanic because he or she charges a fair price for their time?

OK, I will stop, you get the idea. Please share. We need the support so we can keep doing this work.

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Dick Stevenson

Hi John,
An excellent reminder list. I look forward to the follow-up articles. Well done.
As an aside, I particularly like the adjacent “Please Share” request with the quite pertinent rational for doing so.
Dick Stevenson, s/v Alchemy

Marc Dacey

I just linked this to a Facebook group to which I belong. This info applies particularly on the Great Lakes for a somewhat obscure pair of reasons: a) a lot of people get their safety notions from the habits of club racing, which aren’t always applicable, as you’ve rightly pointed out, and b) a lot of “good old boats” are distinguished in fresh water by very worn down anti-skid and insufficiently beefy (or equally worn) lifelines/stanchions, etc. In brief, it’s easier to slide off a boat with a toerail than gunwales, and I’ve seen enough short, steep waves to provide the motive force. Yet tether use is rare here, but the water’s just as cold much of the year.

Samuel Teel

As a rock climber, I am very aware of the injurious or fatal effects of falling on a low stretch rope. Climbing rope is dynamic vs static. A fall of only a dozen feet on a static rope can be fatal. Climbing rope will stretch nine to thirteen percent for this very reason. Absolutely no one rock climbs on static rope. Yours are the first comments I’ve seen relating this concept. Btw, Although I am in the Juan De Fuca straights in the PNW, I find so much of of this website that seems to apply directly.


Hi John, thanks for this online book as I consider this topic one of the most important and vital topics of sailing not only off- but nearshore as well.

EW (Ted) Clucas

John ,
Thought I would add to the list of DONT’s . Even if you are tethered well and short don’t lean over the life lines with more than one arm . Stay in a Crouched position . I was from the waist over the life line taking out reef stop . Did not get wet , but good version hiking out a star boat . Couple of raspberries and some sobering thoughts in the bunk later . My 2 cents

Todd Smith

Good morning John,

Thanks for collecting all the wisdom and issues around this topic into one place. We have adopted your mantra of “treat the edge of the boat like a 500 ft cliff” and I think our resultant action and strategy are much safer now when offshore.

Regarding the harness, tether and crotch strap issue, we have not found any sailing products that match the safety and comfort of rock climbing products or even industrial products. In climbing and industrial applications this problem was factored long ago and is far more evolved than what I can find in sailing products.

Note that none of them use a crotch strap. The use leg loops to safely distribute the load and in general all straps are overly wide for the same reason.

I learned 35 years ago in climbing that neither a chest harness nor a sit harness were sufficient alone to safely arrest a fall and avoid collateral shock injury, so I used both. I have fallen as much as 10 feet and while it hurt like hell, I was mostly uninjured and I didn’t have to worry about tipping out of a sit harness or sliding out from underneath a chest harness.

Next year we will likely adopt a climbing sit harness (also great for a bosuns chair since those are mostly poor as well IMHO) along with our life jackets with integrated harnesses, but having looked at I think all the models out there I still haven’t found one that approaches the quality, fit and adjustability of harness that I would really feel confident in. I may end up moving to climbing harnesses for the chest as well, but that all adds a layer of wardrobe complexity I would rather avoid.

Thanks again for another great post!

Now if I can only figure out how to configure a usable centerline jack line….

Peter Chandler


First, thank you for all the work and thought that you have put into this series. I readily admit to being shocked by own ignorance about POB prevention, the perils of becoming a POB, and the obvious (now) merits of the centerline jack line strategy. Second, thank you for sharing Wilson Fitt’s practice and rationale in Chapter 3. Given the growing quantity and scope of your writing on this topic, I might suggest that occasional repetition of Wilson’s profound words would remind readers of the importance of THINKING correctly about staying aboard.

Now, a multi-faceted question: I might characterize my sailing into three different categories:

1. Coastal and offshore cruising on relatively small (say under 50 feet) boats with relatively small (say under 7) crews of experienced and occasionally inexperienced sailors.
2. Competitive ocean racing on relatively small boats with large crews (say 8-10, with 4-5 on deck at most times) of mostly experienced sailors.
3. Large vessel (c. 100 feet) deliveries, with large (15-20), mixed crews of “professional” (e.g. USCG licensed), experienced amateur, and novice sailors.

The centerline jackline concept is clearly the preferred approach in my first category. It would also be the preferred approach in the other two categories, but for the need to accommodate more people. Have you given thought to laying out or managing the use of multiple tethers that are permanently attached to centerline jacklines for use by a crowd?

My question is not intended to challenge the concept–just the opposite. Having agreed that sideline jacklines are fundamentally unsafe, if I were preparing a boat to race offshore, what would I do? The right answers might be to sail with smaller crews and/or forbid the common practice of packing the windward rail with heavyweights with their legs draped over the side. Assuming those answers are not acceptable for competitive reasons, might there be a protocol for a crew member leaving one tethered position for another (say leaving the windward rail to take over as jib trimmer in the cockpit) to detach and reposition the abandoned tether so that it will be clear for the next crew member to join the rail? Another quandary is how to enable a crew member to move past another without becoming momentarily “unclipped.” Might this call for redundant centerline jacklines, one for those parked on the rail, and another “express” jackline for those needing to travel to a different part of the boat? Obviously this monologue conjures up images of a tangled web of loose tethers that would likely become a hazard in dark and stormy conditions.

The same questions would arise in the case of large vessel deliveries, but they seem easier to answer, or the better answers may involve fewer compromises, simply because there are normally fewer crew movements. On the other hand, there are situations, like dousing or reefing a large sail, in which there might be 15 people working in close proximity to each other.

I don’t mean to suggest that you have any responsibility to answer these questions–rather to invite thought and discussion by you and the other followers of your research.

Again, my sincere thanks for bringing the discussion this far.

Drew Frye

I suspect you’ve read my comments on using dynamic materials for tethers instead of low-stretch webbing. My current tethers are 7.8mm glacier travel rope. I have jacklines and also numerous climbing bolt hanger hard points.

While working, mostly single-handed, testing speed limiting drogues for an article, I got thrown hard against my tethers repeatedly. There is no “one hand for yourself” when horsing around drogues in rough water. If not for the substantial give I would have been black and blue. As it was, the tether just felt like a firm hand. The tethers were clipped to hard points on the hard top, and lengths were set such that I could not allow me to move beyond the rail.

Gotta stay on board. Singlehanders don’t believe on POB recovery.

Dick Stevenson

Hi John & Drew,
I did not buy my drysuit with ease of donning in mind and have never done so alone. Thinking about it, it could be done, but not quickly. I really only have one interior layer: for cold water, and it is always damp w/ sweat after a period in the water. I think of the drysuit as coming into its own passage making if I had to be at the helm for long periods in rain or ugly wx. My under-layer is substantial, so I might use it for quite cold conditions (below 40F/5C), especially if the boat interior was also cold. Sometimes the chill seems to go right through foul wx gear when sitting around in a way that I think might not happen with a drysuit and substantial under layer.
My best, Dick Stevenson, s/v Alchemy

Eric Klem

Hi John, Drew and Dick,

I have never sailed in a dry suit but being a former whitewater paddler, I have used them a fair amount. I can see where it would be really helpful and potentially life-saving in an immersion situation. There are a couple of downsides in addition to the ones you have listed that are worth thinking about.

If your primary foulies were a drysuit, it would be vital to have a second full backup set of foulies. The reason is that you will occasionally break a gasket on a drysuit, usually during donning or removal. While they are not overly hard to replace, you would need to have a backup. These things are really not designed to keep you dry once a gasket is gone. I have had to deal with many miserable, cold people on river trips with a blown gasket that we basically were force to duct tape to their skin. In whitewater, the amount of water you can take on through a broke gasket can actually become dangerous.

I think that these would be very hard to don in the dark or under red-light only. You could probably get used to it but there are a couple of awkward moments where you are really immobile and blind.

Dry suit gaskets really choke you and make it difficult to breath. I find that it wears me out even with a properly stretched gasket. A few hours is fine but all day really wears me out.

Overall, I think that there is merit to the idea. Failing foul weather gear can truly be miserable. I actually switched to Grundens almost 20 years ago as I felt like I never knew when my fancier gear was going to spring a new leak and I have been very happy with them but they are not for everyone or every situation.


Drew Frye

Speed of donning. The US Coast Guard standard is 3 minutes, and I can done in 3 minutes without rushing, with practice. Proper under layers help.

Overheating. I use it kayaking, which generates lots of heat. The suit is Goretex and I don’t like it above ~ 55F. At 55F I will only wear a single layer, which is enough in reasonably cold water. One major advantage of the Ocean Rodeo suits is the stand-by function, where you open the neck down to the chest, but zip the jacket. A wind breaker would do the same thing. I can then seal the neck in 20 seconds when needed again. If sailing under a hard top, it would be sealed only when at the bow.

It adds a LOT of confidence ans safety when doing work were falling in is possible. It also makes diving down to the prop barely even unpleasant (add a hood and gloves). You don’t even get your clothes wet! This was VERY handy when I bent a prop a year ago. An easy inspection in November. Every cold water boat should carry at least one.

Drew Frye

I’ve started wearing a drysuit in cold, rough winter whether. A first it was for kayaking, but then I realized it is generally at least as comfortable as foul weather gear in the rain, and there is a big improvement in POB survival. I did a 4-hour test in 32F water, and it was only boring, not uncomfortable. Something for a cold water sailor to think about.

Dick Stevenson

Hi Drew,
I have been using stretchy tethers for a couple of decades, but have yet to really test their stretchiness (and I can continue to wait). Mine are homemade of 1/2 inch 3 strand nylon (NE). Do you have ready-at-hand figures on the comparison of stretch and strength characteristics between 7.8mm glacier travel rope and 1/2 inch (~~12mm) nylon 3 strand? NE gives 7,500 for average breaking strength, but I find the other figures elusive. At first blush, 7.8mm feels like too small a diameter, but, with adequate strength, smaller likely just means easier to handle.
thanks, Dick Stevenson, s/v Alchemy

Drew Frye

I’m not going to post a spoiler; I’m sure John has great research. But the critical thing is to consider not at strength, but toughness. Climbing ropes are not even rated by strength, and finding test results on the internet is nearly impossible. Instead, they are tested by dropping a weight and measuring impact and number of drops survived. My 7.8mm tethers do not quite meet the ISAF strength requirement (there are newer 8.3mm UIAA single ropes that do), but they exceed the toughness requirement by a mile, and that is what matters in a fall. Glacier travel (UIAA 1/2 ropes) are designed to catch crevasse falls and the like, which in my opinion is a fair match to sailing use.

The longest fall I have ever seen (I was belaying the other end) on a climbing rope was about 80 feet. He was fine, though a little shaken.

Drew Frye

A few more tips on a dry suit for sailing.

Seals. These are ALWAYS to tight when new. You might have a skinny neck and they need to be tight for diving. But sailing does NOT require so tight a fit, so begin to trim them, by small degrees, until they are comfortable all day (the adam’s apple is the critical bit for me). Because of the stand-by mode, you are not in the seal continuously. Do read on the internet about how to trim and how to wear the neck seal. Same for wrist seals; they are typically too tight.

Layers. Sailors will adjust these more than divers. Don’t go too heavy. Add a hat if you are cold.

Type of suit. Suits for sailing and windsurfing are different from kayak and dive suits. Try something sport-specific. The sailing suit is far from perfect for diving for example, but it is good enough for what you need. Do be careful to get ALL of the air out by going down the ladder into the water before the final seal. Otherwise you will never swim down!

I don’t think of it as a foul weather gear substitute–Erik was correct in every point–only as a valuable supplement for very nasty weather and for higher-risk activities near cold water. I went for a swim in 32F water once to recover a lost rudder, and I did not enjoy the experience (I was wearing Windblocker Fleece and was overheated when I went in, so I actually avoided serious chill–I did feel as though I had been beaten all over).

Marin Streeter

I’m new to sailing and have just started my on my journey with sailing. My only comment wow I’m glad I joined your site. In my watching so many videos of sailing on YouTube I’am surprised by how many I see use not use a jack line and if they do use a jack line they do it so carelessly and don’t see the danger they set for their selves. I have been thinking about all the things you have covered and will be reading more on your web site. Thanks for a great site to visit. I will not go into my thoughts as I agree you don’t need that here. Marin

Alastair Currie

Looking forward to the articles on lifelines. I have replaced my old coated wire ones with plain wire but now looking to change the current set up from side decks to centre line. I know the perception appears to be focused on recovery of MOB but there is a lot of discussion now around lifelines because of the fatalities. In addition the discussion on UK forums has very much moved from lifejackets to harnesses and preventing falling overboard. This was in part a reaction to campaigns on lifejacket wearing which, while valid, focussed opinion on prevention. It is up to the leisure sailor to change to best practises because prescriptive standards / regulations will always trail behind. Neither can we cant rely on industry to lead the way because they too react to market demands somewhat.

I am against mandatory regulation. That is not because I am some anti authority person, far from it in fact. However, I feel regulation can’t cover all the bases and the leisure sailor should have the freedom of choice. I also know for a fact that legislation, especially prescriptive legislation can reduce the perception of risk as one ticks off the compliance. I would rather be scared witless than face a tempest with a false sense of security because I comply. Incidents are by far very rare and most sailors bumble along quite safely and understand that the sea is dangerous, they feel the fear and respect it.



Drew Frye

a. I think item 10 needs some exceptions. If the boat is over 50 feet long and runs long jacklines (continuous), polyester webbing will be too high stretch and Dyneema will have some stretch at that length (I’ve done some testing). However, you are right about the load multipliers; the line will then need to be ~ 8500 pounds and the anchors stronger; it needs to be engineered to the boat. But I think it is reasonable to accept that at some point, one-size-fits-all breaks down.

b. What brand of tether is high modulus? To my knowledge all current commercial products pass ISO 12401, which includes a drop test requirement that only nylon webbing can pass (ropes too of course–just not high mod). It is somewhat less demanding than climbing rope drop tests (less height, more mass), but it’s still tough.



Hi John,
What type of boarding ladder do you have on, Morgan’s Cloud and where did you locate it, e.g. Transom.