Jacklines (vs jack's line)

[JohnV]

I'm making my jackline (or possibly lines) of Amsteel Blue. They'll run along either side deck of my 33' cruiser, from the sbd c'pit coaming, around the (round) anchor bit, back to the ps coaming.
I'll tension it with lashings through a sailmaker's thimble spliced to one end.
I'll protect it with Yale dacron cover where it crosses the foredeck and wraps around the anchor bit.
Here's the question--is there any advantage to my making it in two parts, vs. in one, as above? Then, each half would have an eye splice foreward for the anchor bit, and lashings at the aft end.
In favor of one part is simplicity: half as many eye splices.
In favor of two parts, is less stretch, though amsteel won't stretch much once the constructional stretch is out of it.
I can't see where either method strains the rope more than the other.
Does anyone know of a reason I should go with one way vs the other?
Thanks for your input and ideas.
John V.

[Ian McColgin]

I've thought long and hard on this one. I've not thought about any of the exotic fibres as it's easy enough to make a durable jackline that still much exceeds the strength of your tether and harness.

Possibly a single long would, in the unlikely event that it broke as you tumble overboard, give enough slack to hang behind the boat and be the Hail Mary line that might save you. On the other hand, two seperate lines are considerably easier to coil up and stow when not-off shore. I have gone with the latter but I don't know that it's a profound difference.

I feel more strongly on not making the jack lines tight. When you fall you're loading the lines about normal to their run. The smaller deflection you'd have with the jack lines not having any slack means far greater strain on the anchors and on the lines. I'd rather have a little more travel in my fall and keep the strain on the system down a little.

I run my jacklines as near to center as practical, as avoids hanging up on vents and such, for a couple of reasons. One is that up along the cabin house puts it less likely to be under foot.

Another is that the more centered run makes it relativly easier to arrange the tether length such that you can get to most everything - even a lot of stuff on the other side of the boat - and still have a length that will keep you about at the rail rather than dragging along in the water. Having experimented with attempting and failing to get back in a boat even moving at a sedate 4 knots when held amidships and fully in the water, I am convinced this matters.

Finally, I have used both round line and flat tape for jack lines. The latter is less of a problem if it does get under foot. Round jacklines have an advantage in that more people already know how to make a perfectly good splice, while the standards for stitching a loop in the end of a tape might take a little looking up.

G'luck

[JohnV]

Ian, thanks for your thoughts. I take your point about keeping some slack in the line. It occurs to me that I could run a few feet of shock cord inside the jackline to keep it taught and out of the way but still allow slack in it when loaded. Maybe I'll do that.
I'd like to center them on the cabin top, but forward of the mast there are too many obstacles--hatch, hard dinghy, and then a big drop from the cabin top to the foredeck.
Running them snug along the foot of the house will at least keep them out from underfoot, and they'll lie flat on the foredeck, where they'll be protected by a cover.
Your idea of having a long trailing line if it breaks, I hadn't thought of, and it's another point in favor of a single line.
I made a short, arms-lenght tether out of the same stuff, because the store-bought 6-footers would have me off the boat if I fell.

[Ian McColgin]

Sounds like you've gotten as far as not getting your center of mass too far past the gunnel. Some quiet day with a safety person to get you out of trouble in the event of failed experiments try tumble scenerios at different positions along the boat. If you have lifelines, see how you hang up with a topple over versus a slither under and through. With lifelines you cannot go aft along the hull to a lower spot so finding out what happens near the bow, where the narrower deck means you could be further over, matters.

In simulation you'll want to take it slowly since the forces get large quite fast and there's no percentage in breaking deck gear. But you may wany an appreciation of how it can feel. Start by just doing a free-hang in your harness. This will give you some useful insights into how to adjust the fit so the shackle through the rings at your end does not crack your chin or poke your throat. Graduate to giving it some bumps working up to a couple feet of freefall. If you're not a climber with some previous fall experience, you'll be shocked.

My current jackline-tether-harness system is a little different due to the needs of my catboat. Marmalade really can't accomodate lifelines without making her more dangerous out of the cockpit and, like many catboats, she has steps on the rudder. I found it well to make my tether long enough that I would hit the water if overboard and I could then work my way aft - jacklines arranged for no obstructions - and around the stern to climb up there. After at anchor tests, I tried it underway and found it works great.

Every boat demands its own set of solutions.

G'luck

[JohnV]

I think experimenting with simulated overboard falls is a great idea and I'll make it a point to do it sometime. I do worry about the issue, as I usually sail alone. My main focus is on fetching up against safety before going past the lifelines. I could see where a catboat would permit a centerline rig more easily than my cutter does for reasons I mentioned above. I'd much prefer it otherwise.
I have wide side decks, a 6" bulwark and 30" double (amsteel blue) lifelines, safety features I'm glad for. But it's an impossible chin-up from the water to the gunwale. So I'll keep the tether short, and avoid too much slack in the jacklines.
JV

[Brion Toss]

Hi,
Simple is good, but it seems that making your jacklines continuous is about as sensible as making all your electrical connections continuous. Vulnerable.
As for configuration, I agree with Ian that, if you must have them on deck, make them well inboard, so it is difficult to fall overboard. Yes, this can make for awkward transitions on installation, but not nearly as awkward as being washed overboard.
My favorite configuration, by the way, is to set up chest-high jacklines, outboard. These need muchshorter tethers, and the jacklines then double as reassuringly high lifelines.
And yeah, don't make these things tight; the loads go up tremendously if you do.
Fair leads,
Brion Toss

[dugout]

You are receiving good counsel. The topic begins with your expectations. I single hand. I, like many others, have come to the firm conclusion that if my center mass goes over the rail I’m dead. Ultimately, my system must keep that from becoming a possibility. Jack lines of any sort just couldn’t do that, bow to stern. Hard points, mid-ship, and short tethers were the answer stern to the mast with the addition of a halyard forward of the mast. This system affords security prior to entering the cockpit from below and in all tasks on deck.
I strongly suggest you follow Brion’s advice and access you and your crews ability to recover from where you end up after a knockdown with the proposed system. I did it and quickly realized I was not climbing back on board even in perfect conditions and 100% healthy. This system must begin with your own reality.

[JohnV]

Brion, your point addresses my original question of one long line vs 2 short ones: which is more likely to fail when a weak point is stressed beyond its limit?

Here’s been my thinking—if you can bear with me:

One long line involves 3 hardware attachment points and 2 splices (given a round turn at the anchor bit).
Two short lines: same 3 hardware points plus 4 splices.
If those are the weak points, then one long jackline wins 7 to 5.

But, with a long line, unseen fatal damage somewhere along the rope—let’s say it's on the port side—can break whichever side you fell against. With 2 separate jacklines, you can fall safely on the starboard side of the boat, so your first fall has 50/50 odds. Fall twice though, it’s 3-to-1 you’ll break the rope. (2 falls can be P & P, P & S, S & P or S & S). Fall more than once or twice, or add more chafed spots, and you’re a goner with either jackline arrangement. (Might as well jump overboard before you break something.)

Intuitively, between the structural weak points and random chafe point(s), one long line seems less vulnerable to me. But that’s all hypothetical, and real-world experience with the issue carries a lot more weight. What do you think of my reasoning?

My thanks to all who have weighed in so far.
John V.

[Dave Mauney]

I like Brions idea of chest high life lines. I wonder where and how you would attach them to keep them that high. I am also confused on the word "outside". I thought the idea was to pull you toward the center of the boat. Thanks

Goodwinds
DaveM

[Ian McColgin]

Different lifeline arrangements mean different tethers. Most people preferr to go forward along the weather rail.

On a two or more masted boat where the jackline can be strung held up at the shrouds (you'll want the final anchor at a chainplate way further aft or forward) this can give you a nice long run and a handy support to hang on to.

I tried it on Goblin, an Alden 43' schooner, but didn't like the clutter. On Granuaile - an LFH Marco Polo - the tendency to extreme heel made it actually safer and easier to go forward along the lee side, which is where most work you'll have to do is happening anyway.

So for me, a jack line bow to stern as much inboard as possible without getting hung on a dorade or such has been happiest, but it is very much worth experimenting as different boats get different long splices.

G'luck