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Tips on satying in the boat by using jacklines.

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Whether cruising with a family or racing to Hobart, Fiji, Noumea, cruising to Tonga Samoa you want to get there alive.


Tips on staying in the boat by using jacklines.



Jacklines are also called ‘jackstays’. But as one pedant friend pointed out, this could be confused with a stay which is from the bowsprit to the stem.


They are lines which are run on deck from the bow to the stern of a boat so that crew can clip on their safety lines and move about the boat.


When to fit them

A not so  common view  is to fit and use them in heavy weather. This is too narrow a view. It may be okay for a fully crewed racing boat but underestimates their safety value for short-hand cruising in even benign weather.


If one crew will be on deck alone for long periods while the other is resting, the on-deck crew could go over the side and not be missed for some hours. In the meantime the boat has sailed away usually on auto-helm.


Wearing a lifejacket is great, but it is greater to stay on the boat than to float.

Although fitted to the deck in monohulls, it is highly desirable to fit additional jacklines on the underside of multihulls. In the event of a capsize the multihull usually stays inverted. With under-side jacklines, the crew can remain attached to the hulls. It is better to stay with the hulls than to be separated from them and in the water. The hulls are also easier to spot by rescue craft.


What are they made of?


Jacklines are usually made of three types of materials; flexible stainless-steel wire, low-stretch exotic rope and webbing being the most common.


Flexible 1 x 19 s/s with a diameter of 4.9mm or 3/16inch wire is easy for crew to insert a loop in each end with crimp swages and thimbles. Their disadvantage is that being circular in diameter they are an under-foot roll hazard. They can also bang and be noisy on the deck and abrade the deck gelcoat.


Low stretch exotic ropes such as Spectra are extremely strong. They also have the disadvantage of a larger diameter for a roll hazard. Splicing eyes in multiplait rope is not easy and requires a sailmaker or rigger.

By removing the outer sheath, the inner core is not weakened and will flatten out, removing the roll hazard. The inner core is easier to insert loops in the ends. A reasonably competent sailor should be able to insert Henderson eye splices in the ends. But being unprotected from UV, this type will need replacing are shorter intervals.

Web strapping is perhaps the best material. The strapping should have a certified breaking force. The loops in the ends are made by triple stitching. Webbing jacklines are commercially available ready made.


What breaking force?


Yachting Australia Special Regulations for safety equipment requires a minimum breaking force of 20,000N or 2040kgf, as does the Royal Ocean Racing Club Offshore Special Regulations, for rope or webbing.

The line, when fitted, should not be taut. A small amount of slack will provide some ‘give’ with the advantage of reducing the shock load when applied to the line.


How to attach them !


Not much thought is put into how to attach the jacklines some times. Its is highly undesirable to use knots on rope or webbing.

                                                         Did you know this 


A bowline, for example, will reduce the breaking force of the rope or webbing by up to 40% but an eye splice by only 5%.


Use of lacing is also not recommended as there needs to be many loops to maintain the original breaking force of the rope or webbing. Lacing takes longer to install, can fray, become loose and securing knots can undo.

A preferred method of attachment is by shackle.


It is important that there be separate jacklines for each side of the deck instead of one line running round the boat. The reason is simple. If there is a break in any part of the jackline the whole system is lost.


Attach to what?


Attachment points should not be the bases of lifeline stanchion posts. The bracing is not designed for the shock loads that may be applied by the jackline to them.

Whatever attachment point is used, it should be welded or bolted through the deck. Through-bolts should also have a large backing plate under the deck to spread the load.


Toe rails can be used but only if they are through-bolted. Most production boats use self tapper screws and these do not provide sufficient security for jackline attachment points.


Where to put them

It is amusing to surf the net and view advertisers' photos of their jacklines. All are usually run around the gunwale. As this article is about ‘tips’ here is another one. Such a position is not desirable.

Many crew go over the side as they emerge from the companionway, not yet clipped on. I remember well an acquaintance doing just this in Bass Strait. As he came out of the companionway the boat unexpectedly gybed and he went overboard. He was never found.


Racing regulations require that a crew must be able to clip on to the jackline before emerging from the safety of the companionway and unclip once in the companionway. This is also sage advice for cruising.


A jackline on the gunwale is out of reach and out of use.


A preferred placing is to run the jackline inside the rigging deck screws and along the cabin side. This has two advantages. It is within reach of the companionway, but more importantly it restricts how far a crew will be washed along the boat.[ Questionable : This can also kill the crew member : cut him in half : decapitate him. : Bust his hip. ]


OPINION [ I would not recommend it. ]


In another experience, green water came over the bow and the bowman was washed the entire length of the boat, coming to a sudden stop at the end of the jackline and at the end of his safety line - over the stern with a broken leg.

By having the jackline inside the rigging on the deck, the crewmember will be washed along and out side the rigging and his safety line will be stopped at the rigging, reducing the distance he will move and the likely injuries suffered. This method continues to give freedom along the length of the line by simply walking inside the rigging rather than outside it.


If the design of the boat does not permit this preferred placing then the alternative is to fit additional jacklines in the cockpit from the base of the companionway to the aft end of the cockpit. The crew can then hook on, come on deck and transfer to the main jackline.




Jacklines, like any other piece of safety equipment, are only of use if they are installed and used correctly, their function is understood and you are connected to them.


SAFETY INSPECTORS SHOULD HAVE FULL KNOWLEDGE ---TRAINING and they should fully inspect in depth before ticking the box as OK. Some ask the skipper. Skipper points - inspector glances then ticks the box. Safety measures state vessel must have safety / jacklines but do they state how and what type and how they should be attached?

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usually the jackstay should be as near the centre line of the vessel as possible and should run from a strong point right by the companionway to mast, so you can clip on before you leave the cabin.


Your tether length should be set short enough that it is impossible to go over/through the guardrail.


Ideally the jackstay should be raised so your hook doesn't drag on the deck making noise and damaging paint. This is possible if it is tied to the mast. Ours is tied up to the mast with weaker cord to hold it above the deck and then the end fixed strongly to the deck padeye so if the mast is lost then the jackstay won't go with it.


Assuming roller furling then it's rare that you need to go further forward than the mast but we do have a secondary jackstay running to the bow down the side deck for that purpose.


We leave our tethers hanging on the jackstay by the companionway so we can just take the end and hook it to ourselves as we come out.

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How short can make lanyard.  I borowed one off shore that had dual lengths and always used the shorter one because it didnt drag across the windows.


I think I will shorten mine to about 500mm.


I wont be clipping on, anyway wont be good if we flip. We dont lean much and its quite hard to fall off the front unless we are flipping over. Dont plan to flip either.

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How short can make lanyard.  I borowed one off shore that had dual lengths and always used the shorter one because it didnt drag across the windows.


I think I will shorten mine to about 500mm.


I wont be clipping on, anyway wont be good if we flip. We dont lean much and its quite hard to fall off the front unless we are flipping over. Dont plan to flip either.


No one ever plans to flip.  And having done it twice, it always comes a complete surprise! 

I normally agree with not clipping on on a multi, but have done it a few times, such as when blast reaching in big seas and thought I might get bounced off the back, or sailing by myself while the crew sleeps and if I went over, Id be well f*cked.

So never say never...

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Interesting article.  Thanks. I might look at the fixing points of our Jacklines.  


I like our the webbing Jacklines.  Easy underfoot.  


Placement is interesting too.  Being more central makes sense from a safety perspective.  Not always practical to centralise, working around the lines and systems associated with typical racer / cruiser layout.  

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