Homemade dyneema jacklines?

[Ocean Roads]

I am about to add jacklines to my boat. West Marine wants over $100 for a 50 foot piece. Looking at 5/16 Dyneema, which would be just as strong, and 3/4 of the price with my discount.

I’d splice eyes to length in them.

Any reason to use the nylon webbing vs a low stretch high tech line?

[Hobiehobie]

Webbing has the advantage of lying flat on the deck and is less likely to allow your foot to roll over the round dyneema line.

However, we rig our jack lines off the deck anyway, running to the mast and then forward to the bow in the centerline of the boat rather than along the edges. That way, when clipped in, you cannot physically fall over the rail, particularly if you wrap the tether around the jack line and clip it back onto your harness loop to keep the tether short. This also means you don’t have a metal clip scraping along the GRP deck, which prompts most people to tend to it rather than concentrating on what they are doing.

[grantmc]

Originally Posted by Ocean Roads

...Any reason to use the nylon webbing vs a low stretch high tech line?

I'm sure many people have done what you're proposing. The real discipline is ensuring everyone clips on.

You don't usually have the opportunity to see how other people sail on their own boats, but going by what I see on YouTube, most don't bother with jacklines or teethers.

For myself I struggle with cognitive dissonance in that it's good to clip on, sure, but I find the use of a teether impedes my ability to move. They are prone to getting tangled and can cause falls in their own right due to tripping. Also they often mean you travel further on deck because you forget to unclick to travel back to the cockpit and then are harshly reminded when the teether becomes taught.

[Mal Reynolds]

Along with not rolling under foot, another important reason is that the nylon webbing stretches under load. So in a fall, the shock loads in the system - your back, your harness, tether, tether stitching, shackle, jackline, jackline stitching, hard point - all see lower shock loads so less risks of failure somewhere along the chain.

Climbing ropes are super stretchy for a reason. The loads on the harness-tether-jackline chain are way higher than you think. The webbing is also very distinct, easy to recognize in the dark from other lines.

I also elevate them and run them down the centerline. Hard clip in points at working areas: bow, mast, cockpit & stern.

[Breaking Waves]

Originally Posted by Ocean Roads

Looking at 5/16 Dyneema,

Any reason to use the nylon webbing vs a low stretch high tech line?

jfyi - I have not looked but would be pretty sure that West's jacklines are polyester and not nylon.

A lot of stretch in a jackline can allow you to (more easily) go over the side even while clipped in. Super low stretch can put a lot of shock load on, especially if the jackline is strung very tight. Polyester is sort of a sweetspot.

Dyneema is fine, it will do the job if you do the end connections properly. But the peak shock loads on Dyneema could be higher than on polyester, so your static strength really should be higher than the equivalent polyester.

Many of us prefer mostly using fixed workstation tethers - short, just enough length at each station to allow the job but short enough to not allow any chance of going over. You need to then get between workstations, where jacklines come in, but personally I mostly prefer to rely on continuous (or nearly) hand grips. Because again as Thinwater said, jacklines/tethers are a bit awkward.

[thinwater]

a. The West Marine webbing is polyester, not nylon. Nylon will stretch too much, allowing you to go over. Even more so, climbing rope.


b. People don't fall off when they are moving, it is almost always when they are working and not holding on or monitoring the motion of the boat.


Yes, Dyneema will need to be stronger, but that's not hard. Routed smart, you won't step on it, and Dyneema is so skinny the problem of rolling is much less than with polyester rope, which is the usual comparison. I don't think it is much different from webbing, I should test that. I will.


My personal set-ups have all been for multihulls, so no point in mentioning the specifics, they are too different. I personally like nice fat polyester rope, because it can take the UV and is also a good handhold, but ONLY if I can route it out of the way. Depends on the boat.


My pet concern is that jacklines should be like seatbelts or hand holds; always there and engineered to NOT be in the way. Mine aren't. You won't notice them unless you look for them.


---


Formerly, I used jacklines when the weather was crazy, at night, and sometimes solo. Now that my one knee is complete crap and can't even climb stairs on dry land, I use them more, particularly if I am carrying something. Properly rigged, I barely know it's there. I think part of this is a long career rock and ice climbing; I'm used to having carabiners and rigging around. Practice and convenient rigging.

[thinwater]

Some test info. I put on a pair of Gill Race Trainer deck shoes and stood on a gelcoat test plank I have used before for testing shoes and non-skid products. I'll tighten this up before I report on it (more shoes and textures), but give or take:



* Bare: CF 0.62
* 8600# Amsteel: CF 0.31
* 6000# 1-inch webbing: CF 0.23
* 3/8-inch polyester DB: CF 0.18


So Amsteel may be less slippery under foot than webbing. I'm sort of surprised.



I need to test wet; webbing may grip better. I'm sure it depends on how flexible the sole is (this could be a big factor--flexible soles bend around the rope or webbing), but the Gill shoes are probably typical. Bottom line: I doubt Amsteel is measurably worse.


UV resistance is probably comparable, but the Amsteel is stronger to start with. However, they are probably comparable in the % BS they see at impact, because the Amsteel stretches less (there is stretch in the tether and the human body deforms and twists during the impact--I have tested this and this is the approximate ratio ... depending). Amsteel is easier to clip into carabiners (webbing can hang up on the carabiner nose). Webbing has better grip in the hand, if used as a hold, but they both suck. Amsteel is easier for the amateur to fabricate.


APS (now OOB) used to make covered Amsteel jacklines, because people feared the slipperiness of Amsteel, but now I wonder if there was ever any real difference.



Very interesting. My next jacklines -- and they are due for replacement this summer -- will be Amsteel. I will use 8600-pound Amsteel, mostly because it lasts longer and I leave them rigged. I figure about 4 years. The lashing is stronger than the jackline, so no worries there.


On my last boat they were secured to SS climbing bolt hangers. On this boat they are secured to big pad eyes that secure the structure of the boat (akas) and are way strong.



As I get older they are not so much for extreme weather as for my stupid lack of sure footedness. It's not my balance, which is still fine. It's impact and strength. I had a very bad bike crash in my 20s and the years have not helped. The knee will probably be replaced in a few more seasons, but they only last ~ 18 years, my folks lived into their 90s, and I'm not 70 yet. I've got to make it last another 5 years, at least. I wear a very large brace.