Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 30-11-2015, 09:35   #31
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,347
Re: Jacklines and fall protection devices?

A few thoughts:

  • I did the Practical Sailor jackline testing. The factual conclusion is that IF you use low-stretch materials they MUST be at least 2x the ISAF minimum strength to maintain a minimal safety factor. the rest of that discussion is opinion and conjecture.
  • Cutting a Dyneema tether with a knife in the water, while pummeled against the boat, sounds like fun. I doubt it is practical. Those of you that have spliced Dyneema may appreciate this.jack lines, when practical. You stay on the boat, they are not under foot, and the ergonomics are better than deck jacklines. It does generally require installing some hard points and won't work on all boats.
  • Multiple hard points. I think all agree they are a good idea. However the ISO tether standard was changed to include a drop test after several tethers were parted under load, resulting in deaths. The problem is that there is no shock absorption. Thus, only a nylon tether can pass the ISO standard. No Dyneema. I understand that Dyneema is small and curls up nicely in a pocket.
  • Practicality. Obviously we need solutions we will actually use. ISO standards and discussions like this can teach us a lot, but at the end of the day the system need to suit the boat, sailor, and sailing style or it won't be used. I can imagine a lot of different but good systems.
A simple test you should all try, no calculations required and no reason for not trying it.
  • Attach your tether or a material you would like to use to a rigid point like a tree or large mast. Attach the other end to your deck harness.
  • Gather 6 feet of slack, and run at the end backwards as fast as you can, as though you tripped down hill and a wave was chasing you.
  • Observe the impact on your ribs and spine.
Actually, don't do this. I don't want any of you to go to the hospital with broken or separated ribs, or a spine injury. It is likely. Start with only a few feet of slack. You will see that the impact is brutal with non-stretch materials, like hitting your ribs on a counter edge. With webbing it will hurt a lot and you will probably never get past about 3 feet of slack if you run fast. With 8mm nylon climbing rope you can can actually start on the other side of the mast, since it will stretch ~ 4-8" on impact, like hitting padding. This does not increase the chance of going over the rail, since under body weight it will only stretch 1-2 inches, and even under impact, the tether will stretch more but the jackline will stretch less.


now for pure opinion. Does this mean low stretch materials cannot be used. No. It means you need to understand them. One poster mentioned climbers daisy chains. There have been climbers killed using daisy chains for fall protection, because they have no stretch and even a 2' drop results in survivable forces. They are useful for climbing, but they can NEVER be used for fall protection, only for positioning (no slack). Same with any no-stretch tether. Personally, I like a tether I can wrap my hand around and pull on for balance, one more strike against Dyneema. But that is only personal preference.



Cheers.
__________________

__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Old 30-11-2015, 09:47   #32
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,369
Re: Jacklines and fall protection devices?

I think the shorter the tether the better. A long tether gets caught and tangled on damn near everything... and actually can be a safety hazard itself that way. Also, when you do fall over, you want it to be very short.
__________________

__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 30-11-2015, 09:50   #33
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2014
Location: Anacortes
Boat: previous - Whitby 42 new - Goldenwave 44
Posts: 1,735
Re: Jacklines and fall protection devices?

I have been alarmed (scared?) a few times on a pitching boat, especially at night. I really want to come up with a tether system that is simple enough to use and safe enough in practice when it counts. This is one of the best threads for info and opinions I have seen on the forum.
__________________
exMaggieDrum is offline   Reply With Quote
Old 30-11-2015, 10:07   #34
Guy
Registered User

Join Date: Feb 2013
Location: So. Oregon, USA
Boat: Seafarer36c
Posts: 4,308
Re: Jacklines and fall protection devices?

It would be easy to sew a fold into any tether to allow some shock absorption . As the threads break, they slow things down a little. You see that feature used as an indicator in safety belts sometimes. It shows the device has been used.
If you are using a non stretch rope for a tether, you can put something like bungee down the middle. The line would need to squeeze the core to come taught. It can't as bungee is rubber.
__________________
Guy is offline   Reply With Quote
Old 30-11-2015, 10:17   #35
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Jacklines and fall protection devices?

There have been several references to blogs and other DIY testing articles.

It is always more prudent to see what established organizations adopt as standards. SORC, ISAF and OSHA are good references. Although OSHA has no direct marine relevancy, they do give good insight into safety. OSHA was the reason I set up my boat with one jack line down the middle. And the reason I use Kong clips- same as those we purchased for confined space rigs before I retired-- they are the easiest double action clip to operate with one hand. The last thing you want is a single action clip that requires you to think about securing.

At the risk of starting a p*%ing match DONOT use the boom as a connection point for your tether. Way too many ways for that to go very ugly.


Finally, most masts have a dandy hard point built onto them. The eye used to secure the spare halyards and/or spin pole should meet standards as a second hard point.




Sent from my iPhone- please forgive autocorrect errors.
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 30-11-2015, 10:40   #36
Registered User

Join Date: Feb 2011
Posts: 2,105
Re: Jacklines and fall protection devices?

We had four lifeline cables running through and outside each stanchion, a series of padeyes from fore to aft both sides, light strips along the foot of the toe rails, and deep yellow flood lights for night work on deck. As in previous posts, on deck work required bike helmets(foam kind). The jack lines ran fore and aft amidship so no one would get thrown overboard and drown upside down(has happened).Nothing was elastic. Goal was to keep crew aboard and stationary at their task area. Worked well, even when the boat(ws43) was totally submerged(cape of good hope).
__________________
reed1v is offline   Reply With Quote
Old 30-11-2015, 11:46   #37
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,347
Re: Jacklines and fall protection devices?

Quote:
Originally Posted by Snore View Post
.... At the risk of starting a p*%ing match DONOT use the boom as a connection point for your tether. Way too many ways for that to go very ugly.


Finally, most masts have a dandy hard point built onto them. The eye used to secure the spare halyards and/or spin pole should meet standards as a second hard point....
Using the boom as a hard point. Good one. One the more probably side, watch for tethers crossing either a sheet or traveller. I've seen both, and so far the results were only comical and scary. It takes practice to get good habits when in a hurry.

Hard points. I went so far as to mark safe hard points with red paint for the befit of inexperienced crew on my last boat. As you correctly point out, many pre-exist. They are also easy to add using 316 SS climbing bolt hangers--all you need is a pre-existing 5/16" bolt that has some extra length on it.

----

"nothing was elastic." Everything is elastic. What specific materials did you use?

Something to remember is that different boats have different concerns. I sail catamarans; they have large decks to be traversed without handholds, the motion is quick, and the boat can stop suddenly. Monohulls have narrow bows, lean, and are more prone to sweeping waves. Then there is the problem of very small boats, where you crawl forward of cockpit if there is real weather and side-deck jacklines don't work. Different solutions do not always mean disagreement, just different problems.
__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Old 30-11-2015, 13:38   #38
Registered User
 
timbenner's Avatar

Join Date: Jan 2007
Location: Ponte Vedra Beach, FL
Boat: Lagoon 380, 38', I Dream of Jeanne
Posts: 313
Images: 7
Re: Jacklines and fall protection devices?

Short tether, marine grade fittings are a must. One more thought almost as important as the tether.

I found through falling overboard, that my stantions are the perfect height to tackle me right about my knees. Which is exactly what they taught me in football, tackle at the knees!! Most production boats have that problem, unless you're very short.

Solution: Since my overboard experience, I invented a solution that would have saved me. In addition to my jack lines, I tie a 1" nylon jack line strap to the aft stantions rail, then about 4 to 5' up the mid ship mast shroud, then forward to bow stantion rail.

Now when my knee height stantions try to tackle me and I'm headed overboard I have something to grab!!!!!
__________________
timbenner is offline   Reply With Quote
Old 30-11-2015, 13:55   #39
Registered User

Join Date: Feb 2011
Posts: 2,105
Re: Jacklines and fall protection devices?

Great idea. We ran non stretch lines from mizzen shrouds to main shrouds when preparing for rough seas. Worked well as outward handhold at chest level. Trouble we had was inability to keep the lines tight without bending shrouds. Other problem was too many times crew would hold onto these rather than hold on to inboard handholds.
__________________
reed1v is offline   Reply With Quote
Old 30-11-2015, 14:01   #40
Registered User

Join Date: Feb 2011
Posts: 2,105
Re: Jacklines and fall protection devices?

Quote:
Originally Posted by thinwater View Post
Using the boom as a hard point. Good one. One the more probably side, watch for tethers crossing either a sheet or traveller. I've seen both, and so far the results were only comical and scary. It takes practice to get good habits when in a hurry.

Hard points. I went so far as to mark safe hard points with red paint for the befit of inexperienced crew on my last boat. As you correctly point out, many pre-exist. They are also easy to add using 316 SS climbing bolt hangers--all you need is a pre-existing 5/16" bolt that has some extra length on it.

----

"nothing was elastic." Everything is elastic. What specific materials did you use?

Something to remember is that different boats have different concerns. I sail catamarans; they have large decks to be traversed without handholds, the motion is quick, and the boat can stop suddenly. Monohulls have narrow bows, lean, and are more prone to sweeping waves. Then there is the problem of very small boats, where you crawl forward of cockpit if there is real weather and side-deck jacklines don't work. Different solutions do not always mean disagreement, just different problems.
Our safety lines and tethers were braided Dacron so minimal stretch. The only time they might stretch would be under weights that would rip someone apart. Jacklines were coated ss cables. Again, for all practical purposes they do not stretch, except under loads that would kill humans. But you are correct, even a lead brick is elastic under tremendous loads.
__________________
reed1v is offline   Reply With Quote
Old 30-11-2015, 15:52   #41
Registered User

Join Date: Mar 2015
Location: Adelaide
Boat: Adams 31 aft cockpit
Posts: 80
Re: Jacklines and fall protection devices?

For single handing, I run a stout line from the mast foot downstairs in the saloon, which runs out of the companionway and attaches to a strongpoint on the foredeck (or mast outside would work on a smaller boat). Using an inflatable cat 1 vest/harness (PLB in pocket), I clip off onto this line whenever outside the saloon. The harness line is about 1.5m and the jackline doesn't have a huge amount of slack in it - you can measure off the harness line to just the right length to keep you on board, while still accessing all parts of the boat above or below decks without disconnecting. I also usually sail single handed with the boat slightly unbalanced. Light helm pressure to prevent the boat rounding up and tacking - until you fall off, at which point she will round up promptly and tack into a hoven-to position, ideally directly on top of you or slightly upwind...note that locking the helm off, as one usually does to attend to stuff up forward, defeats this safety trick
__________________
mowerandy is offline   Reply With Quote
Old 30-11-2015, 16:47   #42
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jan 2012
Location: vessel sold at LAKES ENTRANCE to a local. Currently nursing my 93 Y/o mother in Sydney. Next boat probably will be bought in the U.S.
Boat: triton 721 24' x 9' 1985 Cutter rigged.
Posts: 922
Re: Jacklines and fall protection devices?

FWIT....My boat is only 24x9 feet and so in the often seriously rough waters where I go being even on the side deck, much less the bow, I hate being out of my Springfield Ladder Back helm chair. BUT crap often happens and so a trip to the sharp end is occasionally essential. (my 250ft of chain and M/Supreme are lifted from the cockpit). For the last six years I have only ever been on the hook. But five years ago I totally shreaded both shoulders and one knee. SO! I fitted Wichard jack lines and tethers, which, history shows, are NEVER worn. NO chance of getting back from even halfway down! So I no longer have lifelines....from bow to stern I rely on 25mm 316 s/s tube. Seriously stiff enough to prevent a fall, always moving with one hand and the rail and the other on the roof, the baby stay or the forestay on a boat which trys often to jump off the planet. At the stanchions I use "T" pieces thru bolted. At the ends I shape and braze the tube to the bow and stern rails. Brazing done with flux coated 45% silver rods with no oxy bottles needed. A SOTA flame gun with hitemp propane is almost a good as tig and NO tradesman (like me) is required. I've fabricated many things using, eg, 3mm plate, 10mm bar etc and so, probably can you. MY system is the best way of getting back on because I'm much less likely to fall off. Seriously solid rails have probably added 10kg to my boat. The extra weight has nothing on my windlass, chainand 5 batteries etc etc. Works for this seriously injured 69 y/o Veteran.
__________________
brianlara 3 is offline   Reply With Quote
Old 30-11-2015, 17:05   #43
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,753
Re: Jacklines and fall protection devices?

I have suspected that 'fall protection' and 'climbing protection' are poor models for sailing jacklines and tethers. In both of those cases you are expecting and protecting from a pretty much straight drop. In sailing that is (very) rarely the case. In terms of load you are much more anticipating a slide, a wave push and in terms of objective you are much more trying to keep the person on board (eg not going very far) than protecting them from fall loads.

This 'hypothesis' is generally supported by actual MOB experiences. Only very very rarely (I can only really find one case) do there appear to have been any sort of significant 'fall' shock loading - looking both at the equipment and also at the resulting injuries. While it is clear from the actual experiences that keeping the person on board is critical to the outcome.

So, while it is obviously useful to look at these two areas for ideas, I think we must consider that our objectives/priorities and actual load cases are quite different that that found in these two areas.
__________________
estarzinger is offline   Reply With Quote
Old 30-11-2015, 17:39   #44
Marine Service Provider

Join Date: Dec 2010
Location: Bristol RI
Boat: Cape George 31
Posts: 635
Re: Jacklines and fall protection devices?

"now for pure opinion. Does this mean low stretch materials cannot be used. No. It means you need to understand them. One poster mentioned climbers daisy chains. There have been climbers killed using daisy chains for fall protection, because they have no stretch and even a 2' drop results in survivable forces. They are useful for climbing, but they can NEVER be used for fall protection, only for positioning (no slack). Same with any no-stretch tether. Personally, I like a tether I can wrap my hand around and pull on for balance, one more strike against Dyneema. But that is only personal preference."



Cheers.[/QUOTE]

I was not suggesting one use daisy chains as fall protection--as Evans just pointed out, it would be almost impossible to experience a fall to the end of your daisy on a boat. I will add, especially if you are using it as I suggested--to tie yourself off short to a strong point. As for sliding one along the boom, in looking back I can see that I usually do this when putting a reef in, in which case the boom is nestled securely on the gallows:no chance of getting flogged around--I suppose it would be unwise to clip into a boom that could be about to gybe, but if it was that far out on one side you'd never be able to reach it to clip in. Again, people, this is not rocket science, but a simple tether.
Ben
zartmancruising dot com
__________________
Benz is offline   Reply With Quote
Old 30-11-2015, 20:16   #45
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,347
Re: Jacklines and fall protection devices?

Quote:
Originally Posted by estarzinger View Post
I have suspected that 'fall protection' and 'climbing protection' are poor models for sailing jacklines and tethers. In both of those cases you are expecting and protecting from a pretty much straight drop. In sailing that is (very) rarely the case. In terms of load you are much more anticipating a slide, a wave push and in terms of objective you are much more trying to keep the person on board (eg not going very far) than protecting them from fall loads.

This 'hypothesis' is generally supported by actual MOB experiences. Only very very rarely (I can only really find one case) do there appear to have been any sort of significant 'fall' shock loading - looking both at the equipment and also at the resulting injuries. While it is clear from the actual experiences that keeping the person on board is critical to the outcome.

So, while it is obviously useful to look at these two areas for ideas, I think we must consider that our objectives/priorities and actual load cases are quite different that that found in these two areas.
Yup, falling is not a great model. But we do need a model.

Jacklines. Absolutely. I have never heard of a jackline failure. However, some group should take a look. I'm pretty a sure a 220-pound guy going at 7 knots horizontally is not unrealistic (that is the energy I used in the testing--I didn't even include slope or the wave chasing him). In that case, the ISAF standard gives a healthy safety factor with polyester, but gives an unacceptably low safety factory if low stretch materials are used. There are a number of reasons we have not seen low-stretch jackline failures:
  • You need really bad luck to hit the end of the tether hard.
  • There is still a safety factor (about 1.5 for the worst case). There would need to be many incidents to cause a failure, probably thousands, since this is only a little less than the safety factor used for UIAA gear design (2.4) for worst-case (a safety factor based on static loading would be 20:1).
  • Many of the people making and installing Amsteel jacklines are going up a size (APS) because they know this.
The ONLY thing I am suggesting is that if you use Dyneema or SS for jacklines, go up a size from the ISAF minimum. Then you are good, that's it. Based on a few Dyneema lifeline failures, this seems prudent. APS, at least, agrees with me.



Tether failures. I've found 3 cases where they parted due to excessive impact force. One involved a roll-over, the others nearly so. In all cases the sailor was in the cockpit, clipped to a hard point. In one case cutting over an edge seems to have been a factor, and in the other the stitching was probably substandard (I believe they tested the some part of the tether). The actual forces involved are likely unknowable. Perhaps they were never survivable.



As for tethers, my reason for exploring this is not zeal for theory, but rather that I have hit the end of a tether and it hurt. I have a catamaran, so long stumbles across the deck are possible; the bow goes airborne, you get negative Gs, and then you stuff a bow into a wave and stop. So I changed to dynamic tethers and I like them much better. Other folks have other priorities.



What is correct for tether we can discuss all day. A drop test is a questionable model at best, but it is what we have. For those that compliance with ISAF and ISO is important, there is a drop test to consider. That narrows your options, for better or worse. I respect those that use Dyneema tethers--many are very knowledgeable--but I personally would not, perhaps because my bones are too old.
__________________

__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Reply

Tags
Jacklines, rot

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fall protection Jd1 Construction, Maintenance & Refit 21 15-03-2014 12:57
Fall Protection Equipment nikki1 Health, Safety & Related Gear 11 15-03-2014 12:46
Want To Buy: Jacklines and Tethers Cruising Couple Classifieds Archive 17 11-03-2012 21:54
Personal Fall Limiter vs Jacklines JamuJoe Health, Safety & Related Gear 13 19-11-2010 19:48
Jacklines and Tethers captain465 Health, Safety & Related Gear 2 01-07-2009 13:52



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 21:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.