Rigging jacklines - Page 3 - SailNet Community
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post #21 of 55 Old 02-08-2011
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Good questions/comments.

Taut with twists – I still like them flat (call me anal retentive). I have never really had a problem with them vibrating and flat is really, really important in a confined space like my cockpit. I will make them taught in harbor before I leave, and in the case of the water knot, there isn’t a practical way of re-tying them once underway. I do not like to pre wet-pre stretch them I believe that that will weaken them over time. Besides half the time we come in after dark and I usually wait until the next morning to take them down and by that time they have shrunk back to their original length.

Routing the jack lines inside the stays - Yes, you wind up scampering over the coach roof/sides, but I don’t find that much of a problem. If they were outside, you would have a problem squeezing between the shrouds and Genoa clew/sheet. Besides, most of the time I (or my crew) only go as far as the mast anyway (reef, adjust Cunningham, outhaul). Also, I like the more secure feeling you get on the leward side when doing things like adjusting the leech line, strop straps or preventer when the boom is extended past the toe rail. I also require my watch captains (as well as myself) to “walk the boat” before they take over at shift change so having a clean run on both sides is important.

Tethers – What? That tether is state of the art Wichard – from about twenty years ago! Remember those days before fancy double action clips and elastic liners? Brings up a good point. Tethers, harnesses, PFDs, etc. are personal gear and if you show up on a boat without yours – you get to use the “boat’s” gear which usually means a cast-off from years ago.

I like a centerline cockpit jack line as it makes it easier to move around people without always having to unclip and re-clip. This is especially useful at night time shift changes for the driver when two guys are manouvering around in a space intended only for one and trying to unclip and clip into that single pad eye at the same time. I started out with the diamond pad eye and later went to the center line jack line and I can tell you from personal experience, it is a whole lot better.

Notes on the photos – These shots were from a series of a couple hundred I took as part of a rig survey Biron Toss did for me. As I was going up and down the mast a bunch and concentrating on my more important rigging issues, I didn’t spend too much effort in staging the jack line photos. I used the old Wichard tether as it was the only one that dangled somewhat straight as I was mainly concerned about the distance of the diamond pad eye to the helm and not so much as using it as a teaching aid.

The one, unasked question – Get lime yellow webbing. At night under red lighting, the red looks like blue and the blue blends into the darkness. You want a color that contrasts to everything else you have on deck. My orange are OK during the day, but for night I’d prefer lime. You can get your local sail maker to make jack lines for less than you buy them at West and you get them in the color and size you want.

Last edited by GeorgeB; 02-08-2011 at 06:28 PM.
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post #22 of 55 Old 02-08-2011
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Originally Posted by GeorgeB View Post
The one, unasked question – Get lime yellow webbing. At night under red lighting, the red looks like blue and the blue blends into the darkness. You want a color that contrasts to everything else you have on deck. My orange are OK during the day, but for night I’d prefer lime. You can get your local sail maker to make jack lines for less than you buy them at West and you get them in the color and size you want.
Chartreuse, safety orange, lime green, and reflective stripe webbing are also available. All are excellent choices and quite visible.

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post #23 of 55 Old 02-08-2011 Thread Starter
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The Wichard LyfSafe jackline is reflective. In the instructions for installation and use, it recommends wearing a headlamp at night, which will light up the jackline.

I'm leaning towards the LyfSafe, as it comes in a convenient kit and it looks like a pretty good setup.

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post #24 of 55 Old 02-08-2011
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I've been searching for some reflective jackline material but can't seem to find any that aren't already pre-made or the only have a breaking strength of 3000 lbs. Any leads on where to find this material?

Merit 25 # 764 "Audrey"
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post #25 of 55 Old 02-08-2011
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Originally Posted by JonEisberg View Post

On a boat the size of the original poster, I’ve really come to favor the use fixed tethers at the base of the mast, just long enough to clip onto before leaving the cockpit… I have 4 fixed tethers on my boat, 2 at the mast coming aft P & S, one on the foredeck, and one in the cockpit…

I have wire jacklines covered with webbing, as well… but since I’ve added the fixed tethers, I find myself rarely using them, the fixed tethers are so much more user friendly for me… Most importantly, once you get to the mast, you can easily shorten them by cleating them off at chest height, leaving both hands free. If I go forward, I can easily be double-tethered, and the one in the cockpit allows me to just reach the windvane, nothing more…

Of course, such a system becomes a bit more problematic on a larger boat, but on most boats under 40’ or so, it should be pretty workable… The big advantage is that your point of attachment is always on the centerline of the boat as opposed to the side decks, and I find myself much more likely to use it in those marginal conditions when I wonder, “do I really need to clip on this time?” (grin)
Great idea for the small cruiser! I have jacklines on either side of my boat but I don't think they are safe. I need one hand to keep the teather moving along the jackline. I am always getting snagged on something. Can you tell me how you attach the teathers to the mast and foredeck? I was thinking of adding padeyes like I have in the cockpit.
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post #26 of 55 Old 02-09-2011
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For ultimate safety for cockpit jacklines .... best is to locate the lines so that you 'clip-in' while still inside the companionway.

Other - Whichever method, either two or one in the center, consider to NOT pull the lines taught but leave some slack. Leaving the jacklines a bit slack will automatically (by trigonometry and by applying loads perpendicularly to a 'tight' rope/wire) puts less load on the 'terminal ends' and the system will have a much higher 'factor of safety'.

For you with math ability ... when you apply load perpendicularly to a 'taught' line, the reaction load in the terminal ends is the perpendicularly applied load divided by the sine of the deflection angle. Dividing by small deflection angles (taught line) result in forces approaching 'infinity'; the more slack the 'line' the larger the deflection angle (dividing by larger sin value); hence, lesser reaction loads in the 'terminals'.
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post #27 of 55 Old 02-09-2011
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Quote:
Originally Posted by RichH View Post
For ultimate safety for cockpit jacklines .... best is to locate the lines so that you 'clip-in' while still inside the companionway.

Other - Whichever method, either two or one in the center, consider to NOT pull the lines taught but leave some slack. Leaving the jacklines a bit slack will automatically (by trigonometry and by applying loads perpendicularly to a 'tight' rope/wire) puts less load on the 'terminal ends' and the system will have a much higher 'factor of safety'.

For you with math ability ... when you apply load perpendicularly to a 'taught' line, the reaction load in the terminal ends is the perpendicularly applied load divided by the sine of the deflection angle. Dividing by small deflection angles (taught line) result in forces approaching 'infinity'; the more slack the 'line' the larger the deflection angle (dividing by larger sin value); hence, lesser reaction loads in the 'terminals'.
I posted this some time ago, expanding on with what you are saying, I think.

Sail Delmarva: Sample Calculations for Jackline Stress and Energy Absorption

Actually, one thing that puzzles me a bit is that there is NO shock absorption when a person falls against a hard point (u-bolt rather than jackline), which can take the forces right off the map. Both OSHA and climbing tethers incorporate a simple shock absorption devise that is be both more useful and far more protective than the "overload" indicators we are now seeing on sailing tethers. All they do is inform you that you have visited the danger zone, not make it safer.

Yates SCREAMERS

Once overloaded, the activation is obvious.

A simple matter of sewing. No one who has ever fallen even a short distance against a hard point will climb without them. For sailing, the required shock absorption would be less.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




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post #28 of 55 Old 02-09-2011
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Are we fooling ourselves about jacklines and tethers. The illustrations posted and the general consensus is that jacklines are rigged along the main deck inboard as much as possible. That is usually less than 2ft from edge of boat in most cases. Tethers come in either single or double tether configuration. One tether is typically 6 ft. long, and if there is a second tether, it is typically 3 ft. long. The Sail Delmarva calculation indicated that the jackline will stretch (deflect) about 2.5 ft. when a 200 lb. man falls. Now, if this man is on the high side and falls towards the low side, the 6 ft. tether will stop him from going overboard on low side provided the boat is 10.5 ft. wide at that point. If he was on low side when he fell, or if on the high side, when he falls from high side into water on that side, he will be dangling about 6.5 ft. over the side. The jackline will recover some but not all of the 2.5 delection after the impact. Most mid size sailboats have a freeboard of about 3-4 ft., so the man is overboard in the water and being dragged along at maybe 5 kts. What are his chances of getting back on board, especially if single handing? If he was using the 3 ft. tether, he is a bit better off, but still in big trouble. Most tether arrangements have a quick release at the harness, so he can either be dragged along, or detach, in which case, he is no better off than if he had not clipped in.

Just raising the question. I have jacklines, lifejacket/harnesses, and tethers on my boat, so it's not that I'm opposed to this gear.
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post #29 of 55 Old 02-09-2011
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We'll never be completely safe on a boat untill we grow fins and gills. Just like a seatbelt, it's added safety, not fullproof.

I'd rather be dragging beside the boat single handing than be left behind while my boat sails off into the distance.

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post #30 of 55 Old 02-09-2011
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Center jacklines

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Originally Posted by NCC320 View Post
Are we fooling ourselves about jacklines and tethers. The illustrations posted and the general consensus is that jacklines are rigged along the main deck inboard as much as possible. That is usually less than 2ft from edge of boat in most cases. Tethers come in either single or double tether configuration. One tether is typically 6 ft. long, and if there is a second tether, it is typically 3 ft. long. The Sail Delmarva calculation indicated that the jackline will stretch (deflect) about 2.5 ft. when a 200 lb. man falls. Now, if this man is on the high side and falls towards the low side, the 6 ft. tether will stop him from going overboard on low side provided the boat is 10.5 ft. wide at that point. If he was on low side when he fell, or if on the high side, when he falls from high side into water on that side, he will be dangling about 6.5 ft. over the side. The jackline will recover some but not all of the 2.5 delection after the impact. Most mid size sailboats have a freeboard of about 3-4 ft., so the man is overboard in the water and being dragged along at maybe 5 kts. What are his chances of getting back on board, especially if single handing? If he was using the 3 ft. tether, he is a bit better off, but still in big trouble. Most tether arrangements have a quick release at the harness, so he can either be dragged along, or detach, in which case, he is no better off than if he had not clipped in.

Just raising the question. I have jacklines, lifejacket/harnesses, and tethers on my boat, so it's not that I'm opposed to this gear.
Precisely. That is why I rig jacklines in the center of the boat. I go from the cabin top (actually the traveller) to the mast, from there to the bow cleat. This also means that each segment (traveller to mast, mast to bow cleat) is only half a long as one long line would be along the side decks, which means it deflects a lot less under load.

Only disadvantage is that I have to unclip at the mast if I go all the way f'ward. Small price to pay.
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