Permanent Jackstays

[lustyd]

Note that webbing has lost 35% of it's strength in 12 months, 45% in 24 months, and 55% after three years, assuming zero use. This is just hanging on a test rack. Assuming you step on them some and the wind moves them around, subtract another 10%. You are well into the danger zone at two years. Far worse than what I am suggesting.

Nobody in their right mind would use nylon for this, and for this very reason. Polyester is quite stable and remains strong enough for at least 3 years.

 

[jonathanhsm]

Many thanks all for your comments.
Re: saying dyneema shouldn't be used for jackstays ... the bloke in the youtube video above clearly disagrees ..
https://www.youtube.com/watch?v=-68Z3bFa_GI
as do chandlers like Jimmy Green who actually market dyneema jackstays ?

As for centre line rigging of jackstay criss crossed at mast - it seems to work for me braced tight against the jackstay and barely touching the guard rail- I rarely go to the bows and if I did i would reclip with second tether..(.if I was clipped on at the windward side Im sure I'd manage to cross the boat and fall over that side !)
see attached article which has been widely circulated in these discussions.
https://www.yachtingmonthly.com/sailing-skills/stay-deck-avoid-mob-51411

hey ho ... nothings ever simple ... but it's good this is provoking debate and maybe making some review their systems.

And while Im on a roll there seems to be loads of disparity on breaking loads etc. ie if you buy 25mm 2000kg webbing - beware the adjustment buckles and D rings/ shackles to fit the webbing - not to mention deck anchor- may have a much lower breaking load.

As i understand it the international standard is 2000 kg breaking strain, yet some Jackstays marketed as a pair (eg Lalizas) have a breaking strain of 1620 kg ???

As I say ... hey - ho.

 

[lustyd]

Re: saying dyneema shouldn't be used for jackstays ... the bloke in the youtube video above clearly disagrees ..
https://www.youtube.com/watch?v=-68Z3bFa_GI

You mean the bloke attaching it to a cleat? I don't think I'd trust him for a variety of reasons as I explained above. Almost everything he does in that video is against best practice for standard yachts. I do note though, it's a performance yacht channel so perhaps it wasn't aimed at cruisers.

Yes, Jimmy Green sell a lot of things for a lot of different purposes. It's up to the customer to make sure they understand what they're buying and why. Give them a call and ask if their fibre jackstays are suitable for your yacht. Dyneema jackstays are used for some scenarios, but not average Joe cruisers on small boats for the reasons stated above. If you want zero stretch and massive snatch loads though, then go for it. Make sure your anchor points can cope , especially if you have a smaller boat as stated where the deck may not be as strong and will need significant backing pads.

Also your choice if you want to unclip at the mast. Nobody is stopping you (unless you want to code the vessel, then you need them up each side), and I've explained for the benefit of everyone else that a core requirement of jackstays is unobstructed movement from cockpit to bow. I don't see an explanation of why you think you're better off ignoring that requirement and standard advice, but it's your boat. Do explain your choices in safety briefings to new crew though, so they can make their own choices.

No, I wouldn't use the ones with metal buckles. It costs very little to have proper webbing jackstays made, and I just made my own set quite cheaply with webbing and v92 thread. I'll attach these with dyneema lashings for adjustment to keep them tight, no need for buckles etc.

 

[zoidberg]

.....Note that webbing has lost 35% of it's strength in 12 months, 45% in 24 months, and 55% after three years, assuming zero use. This is just hanging on a test rack. Assuming you step on them some and the wind moves them around, subtract another 10%. You are well into the danger zone at two years. Far worse than what I am suggesting.

I'm well pleased to see this now with numbers, for I've understood this 'qualitatively' for years and tried - usually failed - to convey a sense of similar caution in others.
This last came up at a 'Jesters Symposium' earlier this year and, as usual, everyone had an unfounded opinion based on their own 'hunch' and 'po-pood' my caution.

'Think of changing my webbing jackstays after about 5 years' was a common attitude.

Other activities have a well-researched/documented set of International Standards - e.g. climbing, rope access, Rescue Services, industrial fall management - and have developed good kit to meet the need. We yotties have a strong reactionary response to changing our ways and enhancing personal safety - viz. the continuing use of old Stubai-type snaplinks with hairy three-strand nylon tethers still seen on some boats "If it was good enough for my grandfather....." - all the while determinedly rejecting sound factual information that there is better.

The Truth is out there!

More power to yer elbow, 'thinwater'....!

 

[zoidberg]

Polyester is quite stable and remains strong enough for at least 3 years.

That's an assertion. A personal 'belief system'.

Show me the data....

 

[lustyd]

That's an assertion. A personal 'belief system'.

Show me the data....

No, it's a widely known fact supported by data. Same source thinwater used, but I chose the material we actually recommend for the job rather than cherry pick the one that looked bad that nobody recommends for the job. A small loss of webbing strength at the start doesn't matter, it stabilises within 12 months and will need replacing every three years, as I said. The ultimate strength of polyester for this purpose is helped by the stretch which reduces the total force on the webbing when compared with something of low or no stretch (physics, not personal belief).

Exposure to Sun and UV-Light - Unirope Ltd.

 

[Graham376]

During a survey, surveyor put his fingers in the sewn loop at one end of mine and pulled it apart with very little effort. The webbing was fine but the stitching was rotten and very likely would have failed with a shock load.

 

[lustyd]

Other activities have a well-researched/documented set of International Standards - e.g. climbing, rope access, Rescue Services, industrial fall management - and have developed good kit to meet the need. We yotties have a strong reactionary response to changing our ways and enhancing personal safety

We have standards too. Unfortunately random people on forums don't look for them and instead choose to speculate. Coded boats have jackstays up both sides of the boat, for instance.

 

[lustyd]

During a survey, surveyor put his fingers in the sewn loop at one end of mine and pulled it apart with very little effort. The webbing was fine but the stitching was rotten and very likely would have failed with a shock load.

Important to use bonded polyester or similar that's relatively UV stable as well as a recognised stitching pattern (and obvs replace every 3 years). I used V92 in a contrasting colour to the webbing for easy inspection. I also don't use red in any UV exposed place as it's almost always less stable.

 

[MontyMariner]

You'd need to unclip at the mast and lose protection.

OP might be using a two tail tether, as I do, so no loss of protection.

 

[lustyd]

OP might be using a two tail tether, as I do, so no loss of protection.

There is some loss of protection since you have added an extra shot at clipping in badly and you'll be doing so near the bows in poor conditions where you might not notice. You've also added a trip hazard with the additional tether and usually with such systems introduced multiple additional chafe points to the jackstays while also putting the clip nearer various things like deck organisers which may catch it (explicitly called out by MCA recently as a danger). It also often results in shorter lengths of jackstay which increases shock loads, reduces stretch and thereby increases the ultimate force on the line.

Now tell me again what's the downside of a single length of jackstay on the windward side?

 

[Neeves]

Now tell me again what's the downside of a single length of jackstay on the windward side?

You are talking exclusively of 'medium' sized yachts. It certainly will not work for multihulls nor larger or beamy monohulls.

On our cat we used a single jackstay from transom to bow along the stanchions, so on the outer edge of the deck and then another jackstay diagonally aft from the bow to the mast across the trampoline. But on larger yachts you do not want a longer tether to get from the 'stanchion' located jackstay to the mast. You need an additional jackstay.

We also had jackstays under the bridge deck. Our cat would not sink and securing the life raft to the inverted bridge deck seemed a sensible option.

I believe current rules on tethers are 2 tails, of different lengths. It is inevitable you may use the long tether to get to your destination and the short tether (or both) when you arrive - to complete whatever the task was. It is inevitable that you might be swapping clips.

The additional tether is not a trip hazard as it can be clipped to the harness

Replacement every 3 years might be sensible in the UK but would be a dangerous recommendation in many parts of the world where UV degradation might be much more severe. I'd speak to the suppliers of sewn tape lifting slings, which are regularly tested, and have them make up jackstays with the appropriate tape. Most would be NATA approved and could certificate the assembly, if asked, and label appropriately.

Jonathan

 

[lustyd]

The additional tether is not a trip hazard as it can be clipped to the harness

Can be, yes. But give a human a chance to screw up and they often take it, which is why in safety situations we remove the chances of screwing up.

Yes I was talking about monohulls.

Replacement every 3 years might be sensible in the UK but would be a dangerous recommendation in many parts of the world where UV degradation might be much more severe.

The testing is based on consistent high UV. In the UK the situation would be better, not the other way around.

 

[thinwater]

This is very clearly not your wheelhouse.
The anchor you used is a climbing anchor with sharp edges designed for metal fastenings/quickdraws to connect to. It'll shred that rope, and any real climber would understand that that's the wrong setup immediately. They often chew through steel when used for climbing and both the anchor and the carabiner need replacing regularly.
You're advocating centre lines, which almost always cause dangerous situations by requiring re-clipping when an obstruction is met such as stays, mast, other lines, self tacking tracks etc. One of the core requirements of jackstays is a single unobstructed run from cockpit to bow on both sides of the boat. Placing them in the centre also encourages use of the leeward side of the boat which should never be done - always heave to if necessary. The centre line also puts the line closer to the edge, making the casualty more likely to be overboard. When on the windward side there's very little chance the tether is long enough.
You're advocating round lines, which roll under foot. You claim you can't stand on them but I'd counter that I've put a foot on almost every surface of my boat while at sea, far better to be safe and use something that just doesn't roll.
You're advocating covering essential safety gear and making it impossible to inspect. This is flat out dangerous. On your list of when hidden stuff is bad you missed chafe, like the kind that's certainly beneath your covering over that sharp anchor!

Also, even if your advice were good for climbing (it isn't!) jackstays are not climbing and have very little in common with climbing systems.

We're done.

• For starters you can't see the anchor because it is covered, so you don't know what is under it. The rope is not dirrectly around the bolt hanger. There are stainless shackles.
• I never advocated centerlines. That was someone else.
• I never advocated round lines under foot, because they roll. Each time I pointed out specifically that my lines were not on the deck.
• You inspection comment is unsupported.

What I suggest is common practice in the US and well proven. You have only one concept you accept. OK.

 

[RunAgroundHard]

There is risk that high side jackstays allow a user to fall over high side with associated difficulty retrieving that person. With centre jackstays that can be eliminated. The fall from centre line to low side is no different from high side, assuming jackstay tension and safety line is set up correctly. Hence centre line jackstays eliminate at least one risk. Granted that other risks are introduced associated with clipping on, off to get around objects.

Many jackstays, conventionally fitted on high side are sub standard: too loose, under sheets, too close to bow and stern, used with single clip standard length safety lines, can still result in having to unclip to do at mast work.

 

[thinwater]

The reason polyester webbing is used is that it has some stretch. Dyneema is designed to have effectively no stretch at all. This will have several effects - firstly the snatch loads of a couple of tons will potentially break the system. It's not just your weight, but your speed and also the fact that the pull is sideways, making the physics similar to a tightrope. Secondly, the snatch load on a human where there's no stretch could cause an injury when in a situation bad enough to make you need a lifeline, worsening the situation.

Jackstays are what they are for very good reason, and while people might say things that sound clever, the standard is almost always best. Don't use dyneema for jackstays, it's fine for guardrails but not for jackstays.

No, this is dangerous. You'd need to unclip at the mast and lose protection. Put them on the side decks and use the windward side of the boat to go forwards. You won't go over the side because you'll fall onto the boat.

• The required amount of stretch has to do with the length of the jackline (nylon stetches a lot, too much for anything but the smallest boat, polyester right for boats 30-40 feet, and too much for boats over 40 feet, as a general rule. I've done the test, and run the numbers. Dynemma does stretch, quite a bit to one side on a lone line that is not excessily pretensioned. So does the tether. In fact, clipping to a hard point would be dangerous if the lack of stretch were lethal.
• Yes, the tension force is greater. 6 mm Dyneema is also stonger than the requirement for this reason. But not my invention. You seem to keep missing this. The idea was introduced by Annapolis Performance Sailing, who were very experienced riggers.
• I don't like centerline or Y jackstays, but many smart people do. I sail multihulls and the geometry gives you latitude to rig them well away from the edges and still not centerline. In fact, on a deck that is 20 feet wide, deck edge jackstays have a rather obvious problem. As for unclipping, they use 2-arm tethers and so are never unclipped. Obvious.

World Sailing accepts stainless and Dyneema jacklines.
Page 17
MoMu0,1,2,3 c) have a breaking strength of 2040 kg (4500#) and be uncoated and non-
sleeved stainless steel 1 x 19 wire of minimum diameter 5 mm (3/16”),
webbing or HMPE rope.

Jackline Materials Evaluation

 

[thinwater]

Nobody in their right mind would use nylon for this, and for this very reason. Polyester is quite stable and remains strong enough for at least 3 years.

Fair point.I inserted the wrong table and did not look closely. Polyester, with wear, will also quickly lose 30% of it's strength before stabilizing.

But the idea of permanent jacklines was ever about not replacing them every few years. It is about having them rigged at all times. Any textile will require replacement at some interval. This is obvious.

 

[lustyd]

That says 20%

 

[Refueler]

To use Seatbelts as example to justify permanent rigged is completely false.

Seatbelts do not sit out in the rain / salt / crap that jacklines suffer. Also that inertia reel belts ... most of the belt is wound away out of possible harm. I can remember old static seatbelts ... faded and frayed .....

 

[lustyd]

To use Seatbelts as example to justify permanent rigged is completely false.

I think it's a reasonable analogy. If it's there it'll get used and nobody would have forgotten to install it. They (webbing at least) don't degrade fast enough that it's an issue, replace every few years and you're all good. It's not a huge expense, although there was a thread recently asking when to replace LJ mechanisms which started with "I can see the expiry date but..." so I think ultimately we have to just trust the process of evolution.