Jackline Installation Tips

Posted by Darrell Nicholson with Drew Frye at 07:45AM - Comments: (13)

Volvo Ocean Race
Volvo Ocean Race

Whether you are clipped into a jackline or not, the safety rule still stands: one hand for the ship, one hand for yourself. A crewmember aboard Amro One, ducks under white water during the 2006 Volvo Ocean Race.

The “to-do” list begins to swell in October, a month when many northern hemisphere sailors start preparing their boats for offshore passages to warmer climates. High on many lists is the job of installing jacklines—the lines running along the deck to which we attach our safety tethers. Jacklines have been in use aboard ships for centuries, and materials have evolved from traditional woven hemp to braided Dyneema, a strong, stiff (high modulus) fiber that is pound-for-pound stronger than steel.

In the our recent report on jacklines, we try revisit the ideal materials for jacklines—webbing, rope, wire, or a combination. We carried out a similar comparison in 2007, but this time around we're looking more closely at how elasticity can have a dramatic impact on the jackline's effectiveness. One of the most startling conclusions of our current test was that despite the International Sailing Federation’s (ISAF) generalized approach to jackline standards, the best material for a jackline varies as boat length increases.

Material selection is just one of many details regarding jacklines that deserves careful thought. If you are re-installing your jacklines or installing for them for the first time, be sure to read our upcoming test report. In the meantime, you can read our 2007 report and review some of the following tips that came out of our ongoing jackline research.

  • Although you can use existing hardware for anchoring jacklines to your deck, finding adequate anchors on light boats can be difficult, since the deck and fittings might not be very strong. Whatever hardware you use must be strongly reinforced and capable of supporting the anticipated loads.
  • Confirm that the entire system is of known minimum strength. ISAF standards recommend 4,500 pounds minimum breaking strength for webbing, although we recommend more for boats greater than 40 feet in order to provide an adequate safety factor. The minimum safety factor is 2.4:1, based on dynamic loads. This means that whatever gear you use should be capable of supporting 2.4 times the amount of force generated by a falling body (or bodies), or by a person who is dragging in the water at maximum boat speed.
  • Nylon stretches a great deal when it is wet, so nylon jacklines should be tensioned when wet.
  • Webbing jacklines should be twisted—not laid flat. This way they are easier to clip into when wet and they won’t flap in the wind.
  • Outboard-powered boats should never have jacklines or tethers so long that a sailor who has fallen overboard could be towed behind the boat near the prop.
  • Jacklines should stop well short of the bow. Fast boats, multihulls in particular, can hurl a person forward when the bow stuffs into a wave.
  • The cockpit should have at least one dedicated fixed point for clipping into. Consider installing dedicated clip-in points (padeyes) at other work stations—i.e. at the mast, or at the bow.
  • Rope jacklines can be acceptable on boats with higher coachroofs that allow the lines to be routed off the deck where they won’t fall underfoot. Rope is more durable that most other choices, it is also easier to clip on and off with carabiners.
  • When Dyneema or stainless cable are used on the deck, sheathing them in tubular webbing can reduce the chance that the jackline will roll under foot. However, some of our testers preferred exposed Dyneema because the carabineers slipped along the jackline more easily.
  • Jacklines must be clearly distinguishable from running rigging, so that there is no chance of clipping into the wrong line. Color is not enough, as the typical side deck is littered with similar control lines and colors are indistinguishable in the dark.
  •  Jacklines should be permanently rigged during a passage. It takes time to become accustomed to their use, and sailors have often gone overboard in benign conditions.
  • Jacklines should be rigged under sheets and over deck-routed control lines so that a sudden tack or jibe does not grab the tether.
  • If you rely on stainless steel hardware, use only the highest quality. (Wichard is one company whose hardware has consistently done well in our tests.) During our field research we came across a 46-foot boat with very tight 3/16-inch stainless jacklines attached with 3/16-inch stainless shackles. Our tester grabbed the jackline at the centerpoint with gloved hands, gave it a maximum effort jerk, and one of the shackles exploded, the cable whipping about. Stainless-steel jacklines must be very conservatively sized to account for hidden corrosion.

For more on jacklines see our eBook Man Overboard Prevention and Recovery.



Comments (13)

Richard Henry Dana in "Two Years Before the Mast" calls attention to long lines towed behind the ship. Working tugboats still practice this ancient tradition. But its gone out of style with "modern sailors". Herman Melville in "Moby Dick" also writes about "towing lines" aft and that falling overboard was not unusual. And even lads who couldn't swim oft had a chance of rescue. Of course if you sail solo then falling overboard becomes more serious. There was a time long ago when falling overboard was not uncommon.
And without the fancy gear. Falling overboard on a warm summer's day ought not be ignored. Two lessons emerge. First the trailing line can't ever be long enough. Second, its bloody difficult to climb back aboard by oneself. Even if blessed with muscles onboard a moving boat. In fact at 6 or 7 knots it takes Herculean strength to merely hold on to the trailing line. Which is why if we care for our crews or their families we'd post 2 crew in the cockpit when voyaging. And we haven't even mentioned jack lines have we ?

Peter I Berman
Norwalk, CT
Author: "Outfitting the Offshore Cruising Sailboat" Paracay Pub.

Posted by: Piberman | December 27, 2018 6:46 PM    Report this comment

I'm relatively new to large boat sailing and be very helpful to me to have some diagrams of the boat in plan view showing to Jack line and Pad eye arrangements for a mono hull in the 30' to 45' range

Posted by: Coralhead | December 27, 2018 6:38 PM    Report this comment

Most sailors can figure out what size and material to use. And if they're well stored when not used they'll last a long time. The real problem here is not the lines but the fittings used to secure the line to the deck. Here's there's no substitute for really stout ss diamond plates or eye bolts each with heavy duty back up plates with 5 ton ratings. Yes that's pretty high. But most of us only have one life. And if the fitting gives out we have "problems".

More. It's long been believed that most sailors are lost when they're the only ones on deck. So its good practice when using jacklines to always have another hand on deck fully suited up to provide backup. Or it worst happens to keep an out as the over board crew drifts off in the distance.

We always had another jack line rule. Required suiting up with life jackets and a big knife.
More than a few sailors gone overboard had real difficulty cutting themselves loose when needed to stay above water.

Our last rule was no one goes forward at night unless absolutely needed and then we had 2 crew watching. One with a floodlight. The other on watch. These rules might seem like "sissy" but over 200,000 miles we always came back with the same crew we left with.
Which is the whole purpose of jacklines anyway.

Final note. In the Great Age of Sail jacklines were rarely used. The old dictum was sufficient. One hand for the boat, one hand for the crew.

Posted by: Piberman | December 27, 2018 2:06 PM    Report this comment

We have a third Jackline on our Freedom 38. It runs from a pad eye reachable from the companion way to the aft end of the cockpit, near the helm seat. We can clip in while in the cockpit & still easily move about. I also use it when exiting the cockpit to do something on the immediately adjacent side decks.

Posted by: Sailmon | December 30, 2017 6:26 AM    Report this comment

On our 34' Catalina, I rig our Bright Yellow jack lines, port & stbd every trip onto the ocean.(aft cleat to bow cleat, tensioned with a line from the aft end of the Jack line to the aft cleat) That way they're not exposed to UV while tied to the dock. my 'Rule' is: If the boat is not tied to something or is moving, then everyone outside of the cabin has to wear their PFD and if on the Ocean, anyone going outside of the cockpit must clip on to the Jack Lines. The Lay flat is a non-issue as crew must clip on while preparing to leave the cockpit.

Posted by: Britinusa | December 24, 2017 8:45 AM    Report this comment

Like any rope built for climbing or professional work have a stress alarm weaved to show when a WLL has been exceeded, the jacklines should have some UV test inserted in their fibers.

Posted by: albatrosbis | December 22, 2017 4:03 AM    Report this comment

The problem with webbing jackstays is that clipping onto them when they lie on the deck is difficult. It is also the case that common clips can catch on the webbing when you slide the clip along the jackstay.
One solution is to have a stainless steel loop on the jackstay. This makes it easier to clip on and it slides along.

Posted by: bobgarrett | December 21, 2017 9:44 AM    Report this comment

I used Plastimo webbed jacklines on my Tayana Vancouver 42 going to/from Hawaii in 2016 from WA. The yellow color made them obvious and the flat webbing prevented the much talked about rolling when stepped on. The jacklines went from both aft port and starboard cleats to the bow. However, in ordering them they were either too long or too short for my boat. I chose the shorter ones and the crew rigged a stout line for the last couple of feet after the lines came together on the bow. They were installed the day before departing offshore and the entire crew participated in their installation as well as life raft placement and securing which gave them confidence in them...afterwards there was never any question. Luckily, they were never needed for an actual MOB.

~ ~ _/) ~ ~ MJH

Posted by: MJH | December 20, 2017 11:53 AM    Report this comment

I think if you have enough slack to reach the bow you'll have a floppy mess that will allow you overboard. Sailors strive for tight jacklines; they help keep sailors on-board, they can be used as hand holds, and they stay out of the way. Avoiding unclipping is intriguing, generally solved by using 2-leg tethers or by keeping small job site tethers at the work site. In practice, if you always use the windward line and consider the length of the tether, you can reach most of the deck without unclipping.

3-strand has an awful lot of stretch. Based on testing and calculations (upcoming article), unless you use something very high modulous (Dyneema or SS cable) there will be sufficient stretch in polyester rope or webbing to absorb the impact. Polyester is also available in 3-strand. And remember that rope jacklines need to be off the deck.

Posted by: Drew Frye | October 6, 2015 1:28 PM    Report this comment

On my Islander 30 I was thinking about running three strand nylon rope anchoring one side to an eye in the cockpit running it around the mast (with some slack to reach the furler) and back to the other side of the cockpit. This way you don't have to unclip if you need to get to the other side of the boat and since it's three strand you'd get some stretch to at impact of the load and would stand out from the double brand ropes of the deck lines.

Posted by: Jelomaster | October 4, 2015 9:34 PM    Report this comment

Dacron is a brand name of polyester. Most commercial jacklines are polyester, which is much lower in stretch and not significantly effected by soaking in water.

Both nylon and polyester can hold knots, but the knots must be appropriate to the material, and the knots will weaken the webbing 50-65%. Professionally sewn eyes are preferred.

Yes, UV is very important. Rope does well (larger diameter has more reserve strength), as does stainless steel cable. Dyneema is also quite durable (looses about 5% strength per year to UV in desert testing). Nylon is the weak horse in this regard, losing 80-85% strength in 2 years, and polyester falls in the middle, loosing about 50% in 2 years (seat belt testing, NHRA desert testing--the real world, for most of us, is less severe).

Opinions vary regarding whether jacklines should be left rigged at all times, or only in bad weather etcetera. My personal opinion is that bad weather often comes without much warning, night comes every evening, the water is cold much of the year in most places, and the best way to get used to jacklines and tethers is to use them frequently. Single handing makes the risks more severe. Each sailor should consider his own risk factors.

Posted by: Drew Frye | September 30, 2015 7:16 PM    Report this comment

Shouldn't one of the criteria for a jackline be UV resistance, particularly since it should be installed for the entire voyage?

Posted by: stevet | September 30, 2015 1:24 PM    Report this comment

Nylon webbing certainly does stretch when wet !! What about dacron webbing?
Does it exist? Does it also stretch? Is it too slippery for knotted ends to be secure?

Posted by: snoopy | September 30, 2015 12:20 PM    Report this comment

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