As those of you who have been reading here for a while know, we—Phyllis and I with the help of the smart people that comment—have been working for over three years on better person overboard prevention systems and practices. A project inspired by our realization that current common practice is deeply flawed and may even be worse than no tethering system at all.
If that statement comes as a surprise to you, you will need to read through the rest of this Person Overboard Prevention Online Book before going any further.
Let’s finish this project by looking at tethers:
A great series of articles. I appreciate all the work this took to put together.
In your discussion of the material to make tethers from, you rejected nylon, but it sounds like you may have been considering nylon braid and not 3 strand nylon. In casual research in years past, I thought 3 strand nylon and dynamic climbing rope to be similar in stretch characteristics. I can see nylon braid being 3 times less stretch as 3 strand stretches far more than braid. I am not sure that I would want any more stretch than my (homemade) ½ inch 3 strand nylon tethers already have, but I am looking forward to hearing and learning more.
On another note, I know 3 strand nylon to vary widely in quality: does to same go for dynamic climbing ropes and can you flag some of the manufacturers whose reputation is good.
Thanks again, Dick Stevenson, s/v Alchemy
Thanks for the kind words. See Drew’s comment below for a far better job on answering your questions about DCR than I could do.
Articles like this are hugely useful and, arguably, are even ground-breaking in terms of drilling down to what can really save you and kill you on a lurching deck. It has occurred to me that shorter lengths of round “rope” terminating at strongly backed padeyes might make sense for places like the cockpit where one is a) partially protected; b) tends not to move around a lot; and c) if you do move, you will tend to slide toward the gunwhales, rather than get tossed. This happened to me offshore: it made a strong impression.
Yours is the first mention of the topic where a mix of stretchy tethers and short tethers on jacklines has been suggested.
Thanks for the kind words. The key piece to me is that each of us must tune a good system to our own boat and usage. The mix works well for us but we had to think about the system in total to get to that point.
Hi John. I’m an old climber. I’ve been adapting climbing practices to the “staying on the boat” issue for years., as well as a few others for years. A lot of climbing practices are optimal for sailing solutions.
I have a couple questions: typically, DCR is not available except in standard lengths (50 or 60 meters being standard). Have you been able to source it by the foot/meter? if so, please share. An even more significant question is securing the line to the biner/shackle. What does the research indicate? I’ve used either a ring bend (with secure secondary tail) or a figure 8 on a bight, as one would tie into the rope when climbing. The choice was dictated by these factors: size of the eye in the hardware (if only room for one pass of the line, then the 8, if room for two, ring bend. This is because I understand the ring bend preserves the highest % of the original line strength. I’ve used 8 mm “double rope” ( intended to be used as a pair, not alone) and so the rated strength is lower, and I don’t have the redundancy/safety factor, or at least I want to keep as much as possible.
interesting thoughts in this bit!
As I said above in the post, I will deal with attaching the shackles in Part 2 I was over 2000 words on this post, so decided to split it up so as not to cause too much nodding off!
Hi Again Erik,
I got my rope by the foot from the local Mountain Equipment CoOp in Halifax. They also sell mail order, see Drew’s comment below.
I was a bit surprised to read that the Spinlock tethers should be made of dyneema, which I agree would be unsuitable.
I checked with Spinlock and they told me that they use a mix of polyester and nylon.
Otherwise an interesting article on a very important issue where we will always have trade offs, where it’s difficult to know if we are right or wrong before we are in trouble.
Regards Eivind / Abraxas 3
Now, that’s interesting. I got different information, but admittedly not from the horse’s mouth, so I’m inclined to go with your understanding. I will follow up some more, and revert, thanks.
You were right. See my correction in the post above. Thanks for catching that.
I would never have thought of a mix of tether materials, though I see no flaw in the reasoning. This is definitely a choice for sailors who know their gear, something World Sailing can’t be sure of. For jackline locations, stretch is not needed and polyester has many advantages. The primary places the shock absorption is of value on my boat are the bow (catamaran–wide and totally different from monos) and the transom area, because there I am clipped to hard points, it can be a real jolt, and the tethers cannot easily be shortened without compromising movement. However, even though they have a long leg (9′), they do not violate the “edge of the deck” priniciple. I like to leave my tethers on the line, but I do stash them below when not sailing for a few days. I also might think differently about this with a different layout. 3-strand nylon is is nice to splice, but it has a few weaknesses. The primary problem is that to achieve equivalent toughness (force times stretch) it must be much large in diameter, and thus a hazard under foot. The catch will also be more firm. The reasons are that it does not stretch as much ( about 12% at 20% BS vs 19% at 20% BS) and is not quite as strong. My recollection is that you need 7/16″ (11mm) 3-strand to meet the toughness requirement. That could be a good answer for some people, and certainly would be acceptable for work station tethers, like one that is left at the mast, for example. Quality of climbing ropes is very tightly controlled by UIAA standards. There simply is no market for a climbing rope that is not well tested and with an impeccable reputation. Just look for the stamp (they are required to be labeled on the end). Rope by the foot. UIAA 1/2 rope (the 8mm that John speaks of) is available in 30M lengths for glacier travel. Since I also use 8mm dynamic rope for my main traveler (another place shock absorption is very nice), this is not an excessive amount. Also, http://www.MEC.ca sells 8.3 mm rope by the foot. Just sort by “lowest price first” and look for a UIAA 1/2 rope. UIAA ropes are drop tested using a figure 8 as the baseline knot. First, this means that some loss in strength is assumed in the test procedure. Second, there are other knots that are just as strong and are far more compact. The halyard has tested well, as has the double overhand noose. The main advantages of the figure 8 it that absorbs more energy in the tightening process, and that if tied with a Yosemite finish (extra tuck), you have a good chance on untying it after a good drop; other knots will seize, but does that really matter? A figure 8 with a tuck back really is quite bulky; excellent for a climber’s tie-in, but not for tethers, I think. John’s main point,… Read more »
Thanks very much for fielding all of that on DCR. You did a way better job than I would have been able to do.
Incidentally, one of the things that really struck me about the climbing world was the presence of easy to understand governing regulations on products like DCR—very refreshing.
Thanks very much for your thoughts and information. As John said, they are well put.
It appears that 3 strand nylon checks many of the boxes for a shock absorbing tether (when of large enough diameter for your toughness caveat), although not as shock absorbing as DCR, and I agree that they are handy to make (any length) as splicing is so easy.
I have been using ½ inch (12mm) 3 strand nylon for decades as my tethers and have not found rolling underfoot a problem, I believe because their size is immediately apparent when you happen to get the rope underfoot. The worst I have experienced was a boat where wire was used as a jackline: small enough to not feel quickly and hard enough to roll like ball bearings. I turned to 3 strand nylon decades ago when the only other alternative was Dacron at a far greater expense. That and I could choose my end fittings.
A word to the European readers: for whatever reason, I found good quality 3 strand nylon very hard, even impossible, to find in the Med and also in Northern Europe (the lay was very soft and I found the strands not continuous). Also, few boats use it for dock line so it is far from common. I suspect that I might have succeeded if I looked harder, but I just bought from venders in the US and brought the rope back in my luggage. Bottom line, I would not use any of the 3 strand nylon I found for tethers.
My best, Dick Stevenson, s/v Alchemy
Just a reminder that I will be writing on tether hardware and connecting to said hardware in part 2, so please hold your comments on those subjects until then. This is particularly important now because the plug-in that I use for moving comments got broken by a WordPress upgrade so I have no way to move your comment.
Regarding the dynamic climber rope why not use a screamers?
I know you can buy them in climbing stores.
Some paragliding reservers have screamers incorparated in the raisers.
Screamers are folded webbing that is seewn together and the stiches will break at specific loads
Yes, I’m aware of screamers, in fact I own one, but for a different purpose. I did not consider them for tethers for several reasons:
In summary, I think dynamic climbing rope is a simpler solution to get the shock absorption we need and when faced with two possible solutions to a problem my choice is almost always the simpler one.
Hi Again Peter,
Just found a YouTube on screamers. Looks like a fully opened one only adds about a foot, so that’s not as a big a problem as I feared.
The screamers I have on my paragliding reserv are longer than the one for climbing.
Regarding the elements I think you are right.
I think some one with the knowleg of screamers could make them to reales at lower loads.
That’s a good point: maybe we need some specialized screamer type devices for sailing.
You can find more technical info screamers, how they work, etc. at Yates Gear – the guy who invented them (and still sells them). Screamers can be set up to activate and different loads. The ones made for aid climbing will activate at a lower load than other uses, although I am still not sure if it will be low enough for sailing since all climbing applications assume some energy absorption from the climbing rope.
One trick we would sometimes use to soften the catch of screamers was to slice some of the threads in the bartacks with a razer. It doesn’t compromise the breaking strength overall (the bartacks used to absorb energy are totally different than the ones used to keep the sling together), but will make activation easier. Aid-screamers also tend to be very short – I seem to remember 15cm closed, and less than a foot open.
Yup, I read the stuff at Yates, but, as I said before, given two options I will almost always choose the simpler one and given that Drew’s testing showed that DCR did the job well in this application, I just can’t see the reason to add the additional complication and clutter of screamers. See my comment further up for more.
In fact, I worked with John Yates on some Screamer prototypes for the Open 60 racing guys. They did not catch on, for the reasons John expressed, and so I never wrote it up. They are not even very popular with experienced climbers, as they are heavy, bulky, and only help in very specific circumstances. The construction trades remain the best application. Also helo tethers.
Regarding a softer catch with a fatter line, we will need to see the data. All of the testing that I have have reviewed, and theory itself, suggests a thinner line gives a softer catch. In fact, I have numerous climbing ropes, from 11mm to 7mm, and the 7mm is much softer. On of the main reasons ice climbers like thin ropes is the softer catch (the anchors are only in ice, not rock, and are not always very strong) (the other reason is not chopping the rope).
Any polyester or nylon rope can be dry treated. In fact, regular climbers often re-treat ropes for each ice climbing season. Although the strength concerns expressed are accurate, they are not the real problem or reason. Wet ropes freeze like blue jeans on the line in winter, and when climbing frozen waterfalls, ropes get wet. Thus, I treat many ropes on my boat for the winter season. There are other advantages: dry treated ropes are lighter, they run smoother (the treatment replaces the internal lubricants), and they squeak less. Nikwax Polar Proof is good–use a bucket, soaking and turning according to the directionless, skip the wash and dry steps, and recycle the dregs for more ropes. MUCH better than fabric softener.
A traveller-type jackline system has proven problematic. A sailor can be washed the length of the track (no friction), the track does not provide a handhold as a jackline can (I grab the jacklines all the time), and passing is impossible.
Some sailors have placed loops along the jacklines as a way or providing intermediate work stations. I never tired it, but I can see the usefulness on a boat with very long Dyneema jacklines (think Open 60). They just splice them in, so they don’t catch.
Thanks very much for the fill on all of those items. All makes sense to me.
Great post! I had a thought on UV protection… One trick I use on static rope that I use for top-rope climbing anchors is to cut a piece of tubular climbing webbing with a hot knife (to melt the ends) and then open it up and slip it over the rope for abrasion resistance. For top roping, I have a 4-5 foot piece on the end where the rope bends over the edge of the cliff. The tubular webbing is cheaper than the rope and easier to replace.
For your DCR tethers you could do the same thing for the length of the rope, stopping at the knots (so that the webbing wouldn’t prevent stretching). This could provide (I think) substantial UV protection – at least for everything but the knots. It would also provide protection from dirt and abrasion (two things that kill climbers).
Maybe too bulky to be practical but it’s a thought.
That’s an interesting idea. I have worried about UV degradation on the DCR too. Right now my thinking is just to replace them once a year, but your idea has merit too. One thought though, if the sun can get at the knots, and maybe a bit of line close to them, then we won’t have gained anything since the tether will still need replacing. Hum, maybe we could cover the knots with rubber weld tape?
By the way, as a climber, do you have any idea how quickly DCR degrades in sunlight? Drew?
(In the interest of transparency, I haven’t been an active climber in about a decade.) Generally, as a climber I never really thought about UV because your ropes are only exposed when you are climbing (which for most is several hours, a few times per month during warmer months). If you’re actively climbing, folks generally retire a rope after a season (or dedicate it to rappelling where it’s never shock loaded for another season or so). Although this varies a lot person to person as you can imagine.
I found an interesting paper that discussed UV (and other) effects on climbing ropes:
According to the paper, a researcher observed a 35% reduction in the number of falls (how climbing ropes are rated) after being exposed to sunlight at an altitude of 2250m for 3 months. A 15% reduction at 1834m for the same time.
Another thing to consider is rope performance when wet. Dynamic climbing rope comes in two flavors – regular and dry-treated (aka a “dry rope”). Dry ropes are used for ice climbing (usually doubled 9mm ropes). The conventional wisdom is that you NEVER climb on a regular (non-dry-treated) rope because it’s dynamic performance can be decreased by as much at 70%. Furthermore, a fall on a wet, non-dry treated rope will cause significantly more damage to the rope making less safe even after it dries out. Rappelling on a wet rope is considered to be safe, again, because there’s no shock loading.
Dry-treated ropes are still susceptible to water with prolonged exposure (like on a boat).
All of that said, it’s hard for me to imaging the shock loading on a sailboat to be as bad as falling while climbing (except, perhaps from the mast). In a sailboat if you have a 10-20 foot vertical fall with nothing arresting you…you may have bigger problems. (But I’ve yet to sail offshore so I’m curious what your thoughts on that are.) Also, I suspect shock loading on a tether is way less frequent than on a climbing rope. (Sport climbers frequently falls dozens of times in a single day.)
Thanks for doing that research on DCR, and for the explanation on dry and wet rope, all very useful and would seem to confirm that we should replace our DCR tethers after each season.
And yes, I would agree that a DCR tether on a boat is very unlikely to ever experience the kinds of high fall loads that are common in climbing. Also, as you say, multiple falls are pretty much never going to happen, which is why I was happy going with 8mm rope. That said, it’s important to highlight that each boat owner needs to look at this with child’s mind and not just follow what we did blindly.
For example, our two DCR tethers are on centre line so the fall factors really can’t get over 1 at the very most. On the other hand, if I were using a DCR tether at a hard point close to the toe rail where the potential fall distances and factors are longer and there is drag risk, and probably most important, drag arrest risk, I would be using 10mm DCR and worrying a lot more about UV and wetness affects.
Ropes are often “fixed” esp on descent routes, for years. They do break from time to time, but long after one thinks. That is, they are pretty tough. Having said that, why take the risk – just replace them when they get old. The easiest way to tell is when they get really stiff – usually a sign of UV damage. Plus, when they get all stiff like that, they are a pain to use and you’d want to replace them.
A note on fall forces: thicker ropes have a softer “catch” (i.e. lower fall forces/higher energy absorption) than thinner ones. Rather than adding length as you ponder below to lower fall forces, like in the cockpit, just move to 11mm. But, even a short length of 10mm or 11mm, with knots to absorb extra energy, will reduce fall forces much, much more than webbing tether. At some point, it is all a trade off, and you need to decide what is good enough.
Thanks for that, however, as I said in the post, I selected 8mm because I was worried that thicker rope will roll more underfoot. And given that Drew’s testing showed that 8mm worked well for shock amelioration, I’m happy with that trade off. I guess what I could do is use 11mm for the additional shock absorber after the hard point. That would have the benefit of having a stronger piece of rope at the turning point at the hard point too.
To overcome potential UV degredation and eliminate any possibility of stretch we considered replacing the Jack Lines with a Traveller Rail and a Car down each side of our yacht converging at the mast to run down the centre line to the bow but realised that it was only really possible to fit at point of build.
It’s certainly an interesting idea, but as you say, best done in build. Also you would then, I think, need to use DCR for all tethers since there would be no deflection. There is also another point to think about and that is that I’m pretty sure that traveler cars are designed to take load vertically, or close to, not horizontally. Therefore it would be important to get with the manufacture about this usage. I fear that a system strong enough to meet regulation would be both heavy and expensive.
And finally, what if two people need to use the system at once, but in different places? This would seem to be a problem, since multiple traveler cars could end up in the wrong places.
I guess, all in all, I would default, as I usually do, to the simpler solution: jacklines.
I am also an old climber and have taken a few falls along the way. DCR is very UV resistant somshould have reasonable longevity. On our boat (40 foot Moody monohull), there is no location where I would use a tether longer than 6 feet. I don’t think that the dynamic stretch available in climbing rope would make much difference in a fall with that little travel. Remember that the maximum elongation is at breaking point which would require a pretty significant event. The length of tethers used on a catamaran or a bigger monohull on a fixed point are longer and in those applications the climbing rope will have more shock absorption capability. That said, I think using climbing rope for fixed tethers is a great idea, as the standards enforced on manufacturers are quite stringent. I don’t have the same faith in much of the equipment available, at great expense, in a chandlery.
I too was surprised by the amount of shock amelioration that Drew experienced in his testing by changing to DCR, even though the lengths were reasonably short, none the less he tells us that it was significant and worth while, even at relatively low shock loads, so I’m pretty happy with that since I have great faith in Drew’s testing.
Then again, your concern about very short tethers makes sense. One thought I had was, with our system where the tether remains on the boat, for very short tethers we can increase the shock absorption simply by leading them through the hard point (padeye) and on to another belay point, say two meters away to increase the effective length of the tether in just the same way a climber gets shock absorption benefit from both parts of a rope lead through a high point anchor and back down to the belay. (Hope I got the climbing terminology at least half right!)
That may be a good idea although it increases complexity somewhat always remembering that the ultimate breaking strength will be somewhat reduced by introducing another hard point where the rope turns.
On the subject of non stretch tethers, have you looked at the flat line climbers use for belay slings. These slings have to hold the same forces as the rope in a fall and are accordingly very robust. They are also available quite inexpensively from the MEC or REI in the US. I have not used it for this purpose but I think it has possibilities.
If you are referring to spectra slings, then I definitely don’t want to be using those. And if Nylon, they will deteriorate much faster than my Dacron webbing tethers, see the post for my reasoning on that.
On the subject of climbing sling AKA runners. These sling have many uses on a sailing vessel. I use them as strips to connect blocks to whatever they need to be connected to, girth hitch to all sorts over things, even as a tack extension on the working jib.
But, as part of a tether set up? No. They are totally static. Not a good choice for a tether.
Hi Matt, Drew and all,
I have become a little confused about DCR ropes:
1. Do we buy dry or wet DCR rope for tether and traveler use? It sounds like one should always buy dry treated rope as (Matt reports) wet rope dynamic performance is decreased 70%. That would significantly undermine shock absorbing properties.
a. How long does the “dry treatment” properties last if tethers are left exposed to sunlight and water, ie left ready-to-go on deck?
2. If used for a traveler, exposed to sunlight and water 24/7, would this dictate yearly replacement or reconditioning the “dry” treatment?
Thanks, Dick Stevenson, s/v Alchemy
Longevity of dry treatment. With typical climbing rope use (year round) the dry treatment seems to last about 4 years of regular weekend use before re-treatment is needed. They are not left out 24/7/365 (most of us will also stow tethers), but they are dragged around in the dirt, over rocks, and run through rappel brakes many times. I’m not sure how that compares, since everyone’s use is different, but it is a reference point. And while you are treating the tethers after 4 years, do a few sheets and control lines. You’ll like it and they will last longer.
3-strand vs. DCR. I have no reason to believe there is significant difference in durability. In high chafe applications, 3-strand is king, but this is not a high chafe application and the dynamic portion is mostly hidden by the cover. Climbing gyms use DCRs through ridiculous 10s of thousands of falls–a real industrial application with astoundingly low failure rates. DCRs are better proven than any other material in this sort of impact application.
Perhaps a little time spent trad climbing is needed to appreciate just how highly engineered and tested these products are. Consider the thousands of times climbers have taken enormous whippers, with a the rope grinding around some rock edge, and survived. Watch You Tube. While they are awful for mainsheets, but when it comes to absorbing impact, absolutely no pains have been spared with regard to research or testing.
I don’t think I’m a fan of leaving DCR in place unless it is with the intention of replacing it every 2 years, perhaps that is because I am very conservative with climbing gear. That said, I have been using 8mm DCR for my main traveler for 3 years (other sailors do this too), and it takes a more serious flogging than most tethers ever will. I’m sure it has quite a few years left. They are not that sensitive to UV.
Thanks for your input on the utility of DCR. Can DCR be spliced? If so, do you, in any of your applications of it, splice DCR?
I will have lots more on attaching stuff to DCR in part two, in about 5 days.
Thanks a great deal for filling in the gaps. One of the continual joys of AAC is the regular infusion of been-there/done-that information and experience. Dick
Hi John and all,
Just to play devil’s advocate for a bit:
What degree of problem are we talking about? How many cruising (not racing) sailors have experienced hard falls where their tethers have needed to do their work? How much damage was done to the person (assuming that they were likely using non-stretchy tethers). I have tugged mine upon occasion, but have never needed it for more than stabilizing and can remember no one describing coming up hard on theirs. I am quite clear it happens just like it happens that a crew goes overboard and is dragged in the water while tethered: just how often per cruising mile and what is the damage?
I think that these issues are really worth exploring in depth and then to come up with a “best practices” suggestion and then we need to sit back and evaluate once again. Sometimes a “best practices” can migrate into a “perfect practices” that may actually, in practice, be less safe over the long run. In this case:
Do the materials being suggested have complications that may make implementation difficult and may bite us in the future?
For heavily used cruising boats maybe, but for regular offshore wandering boats, is yearly replacement of tethers something likely to be done?
How often do the DCR ropes need their “dry treatment” upgraded if exposed to sun & wet? (especially if “wet” means a 70% decrease in dynamic performance).
How quickly does UV degrade them?
Might more conventional materials such as nylon 3 strand or nylon double braid (with better known properties by sailors) make more practical (and may, in the long run through simplicity, be safer) to use while still retaining a good percentage of the shock absorbing properties of the DCR rope? Possibly they could be used with both fixed position and with jacklines, making for simplicity and making it un-necessary to have different tether materials.
My best, Dick Stevenson, s/v Alchemy
Another factor in the mix here, I think, is the presence of gunwhales versus toerail and the height and strength of stanchions/lifelines. The practice is to prefer gunwhales and substantially strong stanchions, but in reality, many production boats taken offshore have toerails and 24-inch tall stanchions which are just the right height to flip anyone with a longer leg over. One of the more thoughtful design elements on our steel boat is substantial five-inch (13 cm) or so high gunwhales with freeing ports and 1 1/2 inch (4 cm) steel pipe “rails” that are nearly a metre tall with intervening wire. We also have a 15 in. (40 cm.) deep “anchor well” at the bow, meaning it’s hard to leave the deck even if you’d want to without climbing out. Some netting would finish the job.
Consequently, as with Dick’s comments, it may be overplanning to install such an absolutely comprehensive setup in those boats where there are other objects that will arrest a fall that can’t reach the momentum of sliding fully off the deck. Now, taking into account either of our sidedeck “gates” opening unexpectedly (they are bolted shut when off the dock) or being flung from the pilothouse roof, for which I would need a padeye up there, my boat is literally hard to fall from. Other boats are clearly easier to fall from: you can see it on most blustery race nights. So I’m wondering if the deep thoughts presented here are modified by the way the deck of one’s particular boat is laid out and whether that would change one’s approach.
I agree that higher lifelines add safety. Do they preclude the need for being clipped on? That’s up to you. All I can say is that based on my experience at sea I would clip on on your boat and not in any way downgrade my tether and jackline systems from that that we use on our boat. There are a lot of tradeoffs here. For example, your lifelines are a bit higher than ours (30″) but on the other hand our boat is a lot bigger and will have much easier and less violent motion. Is one going to outweigh the other? Who knows? To me, prudent sailors clip on. And if you are going to clip on, why not make the system as good as it can be, particularly when that can be done comparatively simply and inexpensively.
Actually, John, in no respect was I suggesting not to clip on. From narrowly averted disaster, I am a convert to that. However, the mix of materials discussed and questions of deflection and the forces at play in a (tethered) fast slide off the deck are obviated somewhat, to my mind, by gunwhales and beefier or higher than seems customary lifelines. As it stands, I suspect we’ll go for a centerline jackline over the pilothouse to the mast tabernacle, and a second jackline forward to the bow, also centerline and with just padeyes on the aft deck. I’m not sure we need more than Dacron, although the DCR option is an interesting one and I do like the “tethers clipped to the boat, not the sailor” idea immensely. I do concur that “doing too well” is less a sin than not enough. One can’t go overboard when it comes to avoiding going overboard.
You bring up an interesting point. I will leave Drew to answer the technical aspects as he has done below. That said, the bottom line on the use of DCR is that it’s a much more tightly regulated and designed material than anything we have in the boating world. As you point out, three strand nylon varies in quality hugely, not so DCR. That, and fact that we can safely use smaller diameter and so reduce roll risk and that it ameliorates impact more does it for me. Or to put it another way, if I’m going to attach myself to a hard point, why would I use a material that’s designed for dock lines, rather than one purpose designed for the task?
Yes, I will have to have a sensible replacement cycle, but that applies to just about every piece of kit on my boat.
On the issue of whether this is a problem or not, the approach of asking for data, as you have, has come up from time to time over the life of this project. The problem is that we simply don’t have good data in the sailing world. What we have is a bunch of anecdotes, and some tragedies. So, given that, we have two choices: either do nothing because there’s no proof we need to, or apply some pretty simple arithmetic rigour (see earlier chapters on shock loads) and turn to the climbing world—where there is hard data from thousands of falls—for statistics and calculations.
I have decided to take the second option, and based on the fact (not supposition) that quite short falls on low stretch materials can really hurt a person—I’m talking as little as two feet here. My thinking is that just sliding down a healed deck or worse still being hit by a wave could produce impact loads that climbers try very hard to avoid, so I have decided to act. Others will need to make their own call.
Perhaps my concern is at least partly rooted in the fact that I nearly died, and spent a year of my life in rehab, from a fall of about four feet. Nothing like personal experience to focus a guy on understanding impacts!
Well put and well argued and I agree. As to the lack of data, it is always a shame as data always contributes to thinking clearly. And I will also acknowledge from personal experience that serious illness/injury can focus one impressively on not having a second occurrence. Dick
I agree, one of our biggest challenges in the offshore sailing world is the lack of data on pretty much everything. For example, if say 500 people a year were wrenching their backs from coming up against low stretch tethers, we would probably never know, but it would still be a serious problem. This is why I think that it’s so important to apply basic mathematic and engineering rigour and look at our boats and procedures with an open mind as well as apply lessons learned from other disciplines that have better data collection, such as climbing.
The videos of the body weight chunk snapping the climbing leads like ribbon in that test tower was, in fact, pretty persuasive. About the only thing worse than seeing that line snap is picturing what that fall would do if it didn’t snap to the human spine and ribcage.
Hi Dick, John,
When analysing the risk of a sudden arrested fall, we should consider not only likelihood, but also severity. John’s personal experience makes this point really well – but perhaps the consequence of it happening offshore is a bigger risk factor to consider?
Having just completed our offshore medic course, I understand the outlook for crush injuries around the chest or abdomen, without immediate and skilled medical care is not all that rosy. I am no expert but in the primary survey and secondary assessment we should be looking for signs of breathing problems (including punctured lung), internal bleeds, severe shock, crush related complications like toxin release, multiple fractures and even hypothermia if the victim is on deck and cannot be readily moved to shelter. We have been taught that victims presenting with such complications will need evacuation to advanced medical care facilities, which is of course problematic offshore.
Great series of articles thanks John, and most interesting comments from everyone.
Very excellent points and commentary. When I last looked at the Bermuda Race record, as I remember, most fatalities were from going overboard and head trauma from the boom. The boom is a dangerous weapon and some thought should be paid for this with boom brakes, height of boom, preventers and possibly helmets.
I agree, the boom is definitely the most dangerous piece of kit on the boat and must be controlled at all times. We have several chapters on that starting here: https://www.morganscloud.com/2014/03/02/rigging-a-proper-preventer-part-1/
Good point and I think this is particularly relevant for sailors because, as I understand it, the harnesses we wear are no where near as arrest tolerant as those that climbers wear.
Conrad Colman speaking about his Vendee Globe sail:
““I haven’t told anyone this yet,” he said at his press conference. “I fell overboard.”
There was silence in the room. He stared out at the audience and swallowed as his gaze shifted momentarily to his feet; this was no PR stunt.
To a silent and dumbstruck audience he then described how at night, in a breezy Southern Ocean he had been on top of the boom, cradled by the mainsail lazy bag as he rearranged the sail when the lazy jacks broke.
“In a split second, the boom dropped into the water, I had no time to grab onto anything and was dumped into the sea. Fortunately, I was hooked on leaving me trailing behind the boom.
“I was too far away from the boat to get back on board, but eventually one of the waves swept me in sufficiently that I could grab hold of a stanchion. The trouble was that my harness was still clipped to the boom, preventing me from getting back aboard the boat.
“The only way to get back on board was to undo my harness, hang on to the stanchion with one arm and try to scramble back onto the boat. Fortunately I did it.””
Perhaps he could get aboard by himself because the boom is a higher point to clip on than a jack line on deck.
Wow, that is amazing. I have been following Conrad, but I missed that part. I’m guessing that a lot of why he could get back aboard, is, as you say, the higher attachment point, but also that he is young and incredibly fit and strong.
I originally joined (paid for) this site to read the details of the Adventure 40. Articles like this, and the ensuing comments and discussion, are why I continue and will continue to be a member. Thank you to everyone willing to share their offshore experience. Even after nearly 50 years of coastal and in-shore sailing experience, it’s mind-boggling how much more I have to learn.
I know the feeling well, always so much more to learn.
I just came across this bulletin from the UK Marine Accident Investigation Bureau regarding the loss of a sailor in the Clipper race. Apparently his jackline hook became wedged under a deck cleat and was twisted open allowing him to be swept overboard. https://assets.publishing.service.gov.uk/media/5a535cfe40f0b648c72358ff/SB1_2018.pdf
Thanks. We have another thread going on this here:
Great information here. It is hard to obey the one foot rule on my Morgan 382 and still move around conveniently. Also the Morgan’s Cloud system requires constant changing of tethers, which concerns me somewhat. Sometimes I need to move fast, or think I do. And every time I hook and unhook, there is a risk of error. But I appreciate the points you make and am thinking about how to change my system. As always, you provide more thoughtful sailing advice than anyone else I have found. Much thanks.
I hear you on your worries about the multi-tether system. You might want to have a look, or re-look, at the video of me moving around the boat (with actual timings) for reassurance in this post: https://www.morganscloud.com/2014/10/02/staying-aboardpart-iiiour-gear/
As to moving quickly, this post may help on that worry: https://www.morganscloud.com/2013/08/03/the-real-reason-to-use-a-harness-and-tether/
In the final analysis, only trying it will really work to put your worries to rest. I can say that I don’t know of anyone that has tried our system and then gone back to traditional.
Last year we completed a 6 month SW Pacific circuit, with John’s jack line and multi-tether system. During this time we had 8 different crew join us for a leg, with four crew actively using the deck system for the first time, and all 8 using the cockpit jack-lines. All reported great confidence and security without prompting from me. No one ever commented on timeliness, for or against.
The only change we will make for next time is to extend the jack line run to the bow, whereas currently it is divided at the baby stay. This has us swap to a shorter 1.2 m tether for the bow section, but has the unintended consequence of making pole handling much slower and frustrating, possibly leading to the errors you mention.
The biggest benefit we experienced was the absolute peace-of-mind it gave Jenny when we were two handed and she was watching me go forward at night on deck, knowing that no matter what, I was physically tethered within the lifelines. The exception is at the bow so we make a point of not changing the pole at night – if the wind shifts we roll the jib away or change course.
We wouldn’t go back – no way.
Thanks so much for that endorsement, based on real world extended use, much appreciated.
We too are looking at a much shorter bow tether for just the reasons you suggest. Preliminary testing last summer seems to indicate that we can go down to 3′ without substantial compromising work with the pole, but we need to do more experimenting.
Yes, it needs careful experimentation, but my plan now is to leave two shorter tethers at the mast (one on each jack line running either side of the mast). Going forward to the bow we would clip on a shorter foredeck tether, but not remove the longer main deck tether, this saving a step going in each direction). I don’t believe having the second attachment will be a problem, and if I happen to unclip the wrong tether, I will still be attached by the other.
That’s an interesting idea, although we can’t try that because our jacklines, both forward and aft, terminate at the mast, which I think I will stick with because it reduces deflection, and therefore drag risk. Anyway, let us know how it works out.
I am currently questioning ‘stretch’ and how much we really need on a boat, if a climber falls it is likely to be for a greater distance than that possible on a yacht. That lines should keep us away from the guard rail is an absolute and clip on points should wherever possible close to the centre line of the boat, to have a situation where the ‘stretch’ still allows the sailor to go over the rail is far worse than the odd injury caused by a shock load.
Like all of us I have no definitive solution but it is something we should all pay greater attention to and share our thoughts.
We have dealt with this at length in earlier chapters in this online book starting here: https://www.morganscloud.com/2015/11/18/person-overboard-flawed-jackline-systems-part-1-corrected/
This is a great book / series of articles – the fundamental point is to stay on the boat! If you do end up in the water, at the end of a tether, the boat needs to be stopped immediately.
I didnt know which article to specifically put a comment on, as my comments relate to many of the articles. However……… knotting lifelines (even with a larks foot / cow hitch) can substantially weaken the lifeline. Although this is a climbing video, it is worth looking at. We definitiely dont want to be getting into Fall Factor 2 situations on a boat. You are right in saying that the forces involved in MOB situations can be very big indeed – when we add the speed of the boat to gravity, it is increased further when we hit the sea!
I am always amazed that there isnt a greater crossover between sailing and climbing – I have 40 years experience in both and some of the ideas / theory / equipment do have direct crossovers or potential crossovers. The Kong Trango (not Tango! ) is a good example. It was developed for Via Ferrata. There are potentially a few other via ferrata devices (along the lines of screamers) that could have use. One of the potential disadvantages that most shock absirbing systems ahve is the change in length of the tether.
As an aside – what are your thoughts on people looping a thether from their harness, around the jackstay and clipping it back to their harness? I know of a few people who do this – I believe it to be an absolute no-no for a number of reasons (more difficult to clip in / potential single point abrasion leading to failure of the tether/ increased risk of entanglement etc)
Most folk never practice MOB (beyond throwing a fender over the side), particularly with a realistic bodyweight attached to the end of the tether. This is always a worthwhile exercise where folks learn how difficult it is to retrieve someone (or even get an injured person back into the cockpit in rough conditions from the foredeck).
Thanks again for the excellent articles
Lots of good points.
Not that it matters much, but Kong seem to spell it “Tango”.
As to looping the tether around a jackline and back to the harness, I really haven’t thought about it much since with our system it would pretty much never be an option. That said, I’m not sure I can see anything intrinsically wrong with the practice. Anyone else have any thoughts on that?
And yes, practice is important although I’m not sure I would advocate for throwing “a realistic body weight” over the side for practice because of the risk of injury involved—always a trade off between the benefits of practice and the potential for someone getting hurt in said practice.
I’m working on making our tethers and jacklines now and this info is greatly appreciated.
I have a question related to the non-skid material shown on your deck in this post. I looked for a more appropriate post to ask the question but didn’t see one. We are needing to redo that portion of our decks and this material looks great. Can you tell me what it is and any feedback on performance and maintenance? We will be in hot tropical settings so that is also a factor.
If you type “treadmaster” (without the quotes) in the search box at the top right you will get more than you ever wanted to know about our deck covering.
That said, if I was doing the same job today, I would look long and hard at Kiwigrip: http://www.pyiinc.com/KiwiGrip/
You use dynamic rope form the climbing world. This minimize the chock load, very good!
TETHER is attached in their harness in one end
TETHER goes to an Carabiner, wich you fix to an anchorpoint, where you want to work.
TETHER goes back to prussik knot sitting in the harness – and the free end of harness is loose.
This TETHER can be adjustet at any time and you may even shorten it, so that you may support your body, and have boths hands completely free to work.
The actual rope is also dynamic climbing rope, but since the TETHER may be shortened at any time you should not fall and risk being stopped with at schockload. But it this happens, it will stop you anyway.
This is the type of “working-rope” used by arborists.
(often they put the “working rope” around a branch, instead of having a Crab to a fix-point)
This short working-rope gives the arborist support when using both hands with chainsaw + freedom to move at will.
I use this TETHER for my own small 19 ft motor-boat:
It has an ancherpoint on top of the boat – the safety line is adjustable. Going to the foredeck in bad weather I keep the length as short as possible to do my job.
Then I should avoid to go over the side – but stay on deck in the short TETHER.
IF I somehow should be stupid enough to fall over the side, THEN it will be possible to lengthen the TETHER (by slipping the prussik knot) until I get to the stern of the boat – and can climb the small ladder / crawl up via the outboard engine.
This is because I often sail alone + anyway my wife could not lift me onboard anyway.
From Anders Skole Overgaard
That’s an interesting idea, and I can certainly see how it could work well on a small boat.
That said, we use, and advocate for, a multiple tether system, where each tether is right-sized for the place it is used, so we don’t really have the need to add this additional feature, particularly since I would worry about the trip, and roll under foot, risk from that much rope as well as the risk of falling when using both hands to move the prussic knot.
I scoured the internet for a USA source for 8mm DCR in short lenghts to no avail. Hoping someone can respond with a source.
I got mine at Mountain Equipment CoOp.
Hi John! I was wondering … we seem to have a line running over the middle of the boat which will allow us to fall – in the case of my Beneteau Oceanis 500 Clipper – 5 meters from one side to the other. Ouch! What about a system that has lines running along both sides of the boat inside the toe rails and one line running from one to the other, connected with blocks or sliding rings. Like a capital “H” where the horizontal hyphen can slide up and down the verticals. The connecting line (the hyphen) can now run up and down the boat. I connect to the hyphen with something like a seatbelt thingy that stops at high speed to allow me to move from port to starboard and vice versa. Now I can move forward and backwards on the boat because the hyphen line moves up and down both lines in the length of the boat. I can move from starboard to port and vice versa as long as I do it slowly. Any fall should be arrested immediately. Also I can now prevent myself from falling overboard – the system keeps me on the boat. Not great if I have multiple crew but for me, while sailing double handed and being on the deck alone, an idea? Would probably use Dyneema then because the need for stretch is eliminated and stretch would probably be undesirable … now I need to find this arresting thingy and have it be small so I don’t break any ribs if I slip.
Interesting, but it sounds a bit complicated to me and I can’t see that the “hyphen line” would slide evenly. Also I would worry about the trip risk of all those lines as well as stuff hanging up on deck gear. The other thing is that I have never seen a good light but robust “seatbelt thingy”.
I guess, if it were me I would just keep it simple and stick with a centre line jackline. As you say, there’s a risk of falling right across the boat, but, as long as it’s short enough for us not to go over the rail, it’s going to be more of a slide and slither, not a fall.
We have a Beneteau 473 with 4.8 m beam, so not quite so extreme but something to be considered. Our solution was to use our main traveller just forward of the dodger where we have put two strong U-bolts through this very solid track, spaced about 400 mm either side of the centre line. By stepping the attachment points out we have been able to keep the tethers shorter and the fall risk less.
We then have one maindeck jack-line which goes from one U-bolt, around the front of the mast at deck level (outside of the three halyards on either side) and back to the second U-bolt, where it is secured with a Dyneema tail.
As the crew member works forward the boat narrows, but the jack-line also centralises to just the width of the mast. Because of this arrangement, our tethers could be sized so we can’t go over the side on the main deck, but can reach the toe-rails and reach up to work at the boom or mast. The main-deck tethers are 1.8 m long. The foredeck tethers are 1.4 m long.
Using this system we ALWAYS go on deck to leeward, better sheltered from any wave strike and the risk of being swept to leeward. This way, if we do fall it is quickly arrested by the tether. But we can circuit forward of the mast, WITHOUT unclipping and work along the windward side to attend any job (usually changing over the preventer) before returning to leeward. We have tested this set-up offshore with four different crew members now, all of whom reported finding it easy to understand and work with.
The one dis-advantage of this adaption, is the maindeck (webbing) jack-line is doubled in length but the run forward to the mast is only ~ 3 metres, so the stretch doesn’t seem to become an issue. In testing I couldn’t get near the lifeline with a tether on, even if I threw myself backwards with my full weight.
Hope that helps, rather than confuses. Rob
That is interesting Rob. Added bonus is, that if you’re on the high side of the boat you’ll be on the high line on a shorter tether. A fall would be easier on the bones. I have the same layout on my Beneteau and could easily see myself using your system. You have the tethers on the jack line or on your vest? I love John’s idea of having them on the jacklines. So far I have two jacklines running the full length either side of the boat and I have always thought that was more to give me the look of a professional and give my wife the impression that I am really safe now. I think it will do jack s***t in real world situations (excuse my Dutch). If I go out of the safety onto the deck I pretend there is no tether or Jackline and that I am not wearing a vest. I have no illusion whatsoever that if I fall overboard I will die. None whatsoever. I strongly dislike the thought that training and special gear will save me and I am thoroughly opposed to the impression of rescue-ability they convey.
Our tethers are permanently attached to the jack-line with a stitched “soft” eye. The harness end has a Kong Carabiner clip. We find using a soft loop allows good freedom when moving with the loop sliding easily past deck obstructions like halyard organisers, or mast obstructions like halyards. We could have used Kong Carabiners on the jack-line end but didn’t see the benefit. In port or at anchor, we stow the whole jack-line with tethers and don’t leave anything out in the sun. When on passage we have two tethers ready on each side of the maindeck jack-line that are clipped to a retaining loop, one each end of the mainsheet track so they can be easily reached.
A crew member going on deck has their own personal tether (used in the cockpit) which is double clipped and can attach to static points on deck if needed, or to temporarily unclip from the deck jack-lines. In practise we haven’t needed this facility so far. The less crew members (self included) clip and unclip from jack-lines, the less likely they are to cut-corners or make mistakes.
For completion, we have two fore-deck jack-lines (one either side of the baby stay) which attach at the bow then shackle to either side of the mast collar plate, so they don’t interfere with the maindeck jack-line or tethers. Each has one permanent soft-stitched eye tether stowed on the baby stay, easily reached from the mast.