NOTE: The following is written with only New Zealand in mind. While most of the information is fine no matter where you are please just remember the Rules and Regulations may not be. That also applies if you are thinking of lifelines for a use other than on a boat, the rules and reg may differ or even exclude fibre as an option in that case. Obviously the below is also written in low tech terminology where possible and in no way intends to be a definitive legal interpretation. If you'd like one of those ask the powers that be, good luck.
The Desire – To have fibre lifelines that both comply with YNZ Safety Regulations and are of real use should the situation require them.
The Considerations – They must be of real use on a boat in a real life situation is the primary goal. Complying with YNZ Safety Regulations and longevity are very close behind.
The YNZ Safety Regulations – Extract from YNZ Safety Regs 09-12 amendment of Sept 2010 -17.17 The minimum diameter lifeline wire or rope (single braided Dyneema, Spectra, Vectran, Dynex or similar material protected from UV and chafe by a sheath: ...
Note: Dynex is a brand name of a product made with DSM’s Dyneema SK75 by Hampidjan in Iceland, it is not a material in it’s own right. Other identical products are commonly available and go by names of Donaghys Ocean 12 or Armare’s SuperRound75 and a raft of others. All use the exact same Dyneema yarn from DSM.
What is meant ‘by a sheath’There has been some discussion as to just what the Regulations mean with regards to ‘protected from UV and chafe by a sheath’. Some see this as meaning the often used white PVC tube is a sheath. The tubing used for most lifelines in NZ does work well but also breaks down in the weather, some a lot faster than others and some quite quickly.
Some see the requirement and suggest it’s a case of terminology as what NZ usually calls a ‘Dyneema double Braid’ i.e. a inner core made with dyneema fibres with a braided cover of some material be it the same as the core material or a differing material, is commonly referred to in many other countries as a ‘Dyneema with sheath’. The use of Dyneema is just for example purposes here.
In here we should add the wire with a bonded PVC cover. A ‘bonded’ wire is one that has a PVC, usually, covering bonded direct onto the wire. While this is specifically excluded by the Regulations it is often seen on many imported yachts, many who do race or head offshore with those lines, we don’t see this as being quite as bad as the white tube as the bonded cover does show any damage easily. But with that good thing comes the big downside of once it is damaged water migration under that cover can cause the wire issues leading to premature failures. It is highly possible that failure point could be some distance from the damaged section. But as it is relatively cheap and does look quite tidy so we expect it’ll be seen and used for sometime to come, legally or not.
The good and bad of differing sheath options as we see them – The white hose varies in quality and some on the market today are pretty crap really. While the good stuff is still available some others are considerably thinner in the wall thickness and far more prone to UV and weather damage that shortens it’s life span considerably. These hoses also often mask problems below. It is far from uncommon to de-construct an old set of lifelines, which may look fine bar some aging on the outside yet have some serious damaged and broken wire inside them. It is quite easy to slice this tube, and in doing so damage the contents, but then close up making the cut in the tube very hard to see let alone any contents damage. We suspect a lot of boats have been close to total lifeline failure, due to damage, but have had no idea about it. We suspect if the lines had been a fibre we would have seen a lot more ‘I never saw that coming’ failures due to hidden damage.
A fibre sheath we see as a better option as damage is far more easily visible. Once damage occurs it is very hard for it to be concealed even from a cursory glance.
We have seen the odd other sheath used i.e heatshrink, UHMW tubing, garden hose and things along those lines but they are unusual to be seen on many boats not owned by the ‘long haired grass growing freaky people from the back blocks of Waiheke’ types i.e. weird one off home builds that often are more a collection of bits and bobs assembled into a floating object.
It must be recognised here that the use of the white tube is often more for protection of skin and comfort of the users than line protection. We don’t see a huge change in that even if boats do swap to a fibre load member. So with that in mind some caution must be used in the choice of the main load member below.
Also if the tube is to be regarded as a sheath what is to be done about the lower set of linelines that usually don’t have the tubing on them.
Our take on the best way to read the Regulations if using fibre - The term ‘sheath’ refers to an over braided core over the main load member. This take the tubing out of the equation altogether and makes it a comfort accessory only rather than a structural part of the lifelines. Doing this means the same line can be used on both the top and bottom set of lines. If the tube is added on top that only gives additional protection to the most likely line to be damaged i.e. the top line.
Fibre line choice – Again an interesting one depending on how you read the regulations. Using an example of a 9.5mt yacht, being a boat in the most common size range out there. This boat, according to the regulations, requires a 4mm lifeline. In wire that’s easy and you have little options as 4mm measures 4mm but in fibre it’s not so clear cut.
We’ll use 3 differing ropes all of which measure externally 4mm, are available on the NZ market and often ‘look just the same’ to the untrained eye, well 2 of them can.
1 – a 4mm single braided Dyneema, the most commonly seen in use. Break load between 1500 and 2000kg depending on the manufacturer and how they report their loads. Testing shows 1650kg +/- 100kg is a good average number to use, which allows for some not quite perfect splices. The lower break load ropes will physically measure a smaller number than those with a higher break load.
A note of interest here – Hampidjans ‘Dynex’ is often the at the higher end of the break load as it usually measures well above it’s stated size i.e. a 4mm Dynex often measures 5.5mm where say a Donaghys ‘Ocean12’ 4mm will have a lower load but physically measures a lot closer to 4mm.
As the individual Dyneema yarns have a set and known load the strength of the finished line can be manipulated by using more or less of those yarns in the finished line. Some manufacturers have higher break loads and use those in their marketing to say they are better. If any 2 ropes have the same number of yarns they will have the same strength, it’s that simple. As we can see above Hampidjan put in extra yarns so end up with a stronger finished product but at the same time it will also measure larger. So the varying strengths seen in say a 4mm Dyneema braid is more a marketing thing than a physical property thing.
2 – A high performance yachting braid. This is a Dyneema or Vectran like core with a polyester cover. The core or load member of these ‘4mm’ ropes are generally only 3mm and the cover contributes next to nothing to the lines strength. Break load of these ropes is in the 400-600kg range depending on manufacturer. Dyneema SK75 and Vectran are very similar so can be regarded as the same when talking loads. Lower grades of Dyneema, which are fazing out, and the common grades of Spectra are lower again.
3 – A high performance core with a high performance cover. There are many ropes that could be described as that. Most commonly seen in NZ are along the lines of a Dyneema or Vectran core with a polyester blended with Dyneema or Vectran or Zylon (PBO) or sometimes a combination of those in the cover. Some pure high performance covers are seen but usually only on very top end race yachts due to a specific issue like too much heat generation when releasing off winches and the like. Due to the varying options it’s hard to pin a single break load number down but we see usually around 1000kg, which we think is a fair one to use as a general number.
So we can see a ‘4mm’ fibre rope can have a hugely differing range of load numbers depending on it’s construction and the materials used. We are of the opinion and run a policy that the load member or combined members must total the Regulations requirements i.e. a 4mm lifeline must have 4mm’s of load carrying material in it. This will increase the strength of the lines considerably over using ‘any old 4mm’.
What we see as a good fibre line for use in lifelines – baring in mind cost, practicality in fitting and ease of which it can be check by the average boat user who has minimal rope knowledge.
We see a line made up of a high performance material core, of those listed in the Regulations, over braided with a similar high performance material as being the best option.
Longevity of a line like that – Taking into account NZ’s harsh UV conditions this is an area to look hard at. With todays technological advances in materials, knowledge of them and now quite a few years of ‘in the field’ use we don’t see this as a big an issue as many possibly think. While some of these fibres don’t really like UV that much, most are now coated/treated with coating that both holds the fibres in place and provide good UV protection. Dyneema has a reputation of breaking down badly in the UV. This isn’t entirely correct when talking Dyneema ropes as studies have found that an untreated Dyneema rope will suffer UV damage reasonably quickly but only to the outer layer of it, which turns that into a layer which gives the rest of the line far more UV protection. One could say the UV damaged layer is like a raincoat or in aluminium terms ‘oxidisation’, which is a basically inert layer UV can’t penetrate. But with the advances in coatings and treatments UV damage to fibres like this aren’t as much of a concern today as they were a few years ago. So it is generally agreed in the industry a 10% strength lose due to UV damage is possible but that number is decreasing quite quickly.
But it is still advised that when fibre lines of these materials are used it is recommended to recoat them after a few years as a precautionary measure, especially if they are used in a high load or mission critical application. The need for this will fade away as time goes by and the newer treatment ropes find their way aboard boats replacing the earlier generation lines and treatments.
A Practical application of a Fibre Rope Lifelines on a Yacht. What, Why and How
A yacht wanted to replace its wire linelines with fibre lines. It is one that races so needs to comply with the YNZ regulations. It requires a 4mm line to comply with those Regs.
After some searching and testing of many lines for one we thought ticked all the boxes we chose to use a 4mm line made in Italy by a supplier to many high performance race yachts including AC boats and the TP52’s. The line has a SK78 Dyneema treated and heat-set core that was then over braided with a SK75 Dyneema treated 32-carrier cover. The manufacturer has now started supplying that rope with a SK90 heat-set and treated core so any numbers used following will be a little smaller than when the new line gets used.
This line ticked the YNZ Reg size box, the materials allowed box, has high strength, is heavily treated, has very low stretch, reasonably easy to work with and with the 32-carrier cover would be nicer on the skin should a crew member fall against it. It also looks good, which isn’t a requirement technically but is something boat owners do look at commonly. It is also not too bad a price, again a common consideration of most boat owners.
To make sure we were right in out thinking this would make a good lifeline we made a few test strops and loaded them on our test bed. The results were exactly as expected and the strops were breaking in the 1500kg area +/- 60kg. That is approx 50-150kg above the manufacturers listed break load but we know that manufacturer bases their break loads on the rope, with terminations after 6 months in use. Not all manufacturers do that so something to be aware of.
Then as some of us here are anal race yachties with deep pockets and short arms, some of the 99%, we wondered what would happen if we could remove all metal from life lines i.e thimbles and so on. We thought this would be good, should it prove viable, as it would mean lighter lines and less metal components of which are damn good are slicing wet cold hand and expensive headsails. It would also reduce cost. So we made some strops with only soft eyes spliced each end.
To test the theory we set these strops up in the test bed as just as they would be in real life use. We used the same size metal as is commonly seem on pulpit/pushpits loops used to connect to linelines, 5-6mm, and the average seen of the lashing at the other end, 3 complete loops of a 2mm material, in this case we used a Dyneema cored yachting braid. Many only use a Polyester fine braid.
Photos above showing one end lashed, one end reeved on to the simulated pulpit and it set-up in the test bed.
The eye splices were a standard Class 2 core dependant splice with a ‘45 x D’ bury. They were not stitched or whipped so as to get a clean rope only result.
The tests showed the lashings are the weak point and weaker than expected. The lashings were failing in the 650-750kg area. As the lashing line we used is two to three times stronger than a standard polyester line of the same size is it highly likely many boats could have lashings that will fails at only a couple of 100kg, possibly less if they are old and unloved, as many are. This maybe an area YNZ Inspectors should be made aware of as it is a lot less than most boaters spoken to think and expect. The photo shows one of the higher results.
We then moved on without the lashings to see what the line only would do. The end loops were connected using 6mm high-load shackles and high tensile chain, which is very similar to what would be expected in real life when looking at physical sizing of attachment points.
The rope was loaded and remained pretty stable until approx. 1000-1100kg where is showed signs of elongation. At 1000kg of load we were measuring approximately 2.5% elongation, which is in line with what would be expected. The rope was then loaded until failure. The cores failed first, as expected and should do, at loads between 1392 and 1443 kilos. The core failed at the back of the splices bury, again as expected and should do. Where the core failed can be seen in the photo below and has been circled. The cover remained intact, again as expected. We continued to load the rope. The cover only took between 822 and 846 kilos to break.
There was next to no movement seen in the splices until after 1200kg when a tiny amount was observed, that is what the black marks on the splices are for. A fair amount was seen failure but often that is due to the sudden release of pressure making them do weird stuff.
So what happened at either end with having no thimbles sliced it. Nothing, no damage to the rope was seen at either end. We expected that at the pulpit end as it is reeved on and it was the lashing end, the pushpit end, where we expected trouble but nothing seen gave us any reason to be concerned there either.
The lashed ends, left photo, showed some compression but no signs of chafe, heat glazing or anything else untoward. The reeved end, right hand photo, also showed some compression but no signs of chafe or heat glazing. All the ends came up better than expected as we did expect to see something a little not good but close inspection showed none.
So with all that in mind we are confident using soft eyes with no thimbles is fine and doesn’t result in lose of strength as long as they are done correctly. But that is with this specific line only as we haven’t done it with others as yet.
One unexpected bonus of this testing is we discovered that when the core breaks the elongation in the rope will suddenly be a lot higher yet the cover still has a very good amount of strength left in it. So should something bad happen and the core fail it should be immediately obvious to anyone even those with no knowledge or low practical skills. But the remaining cover will allow some half decent level of security to get the boat home with at which time replacement can be done.
So in summery we were very happy with our rope choice and it’s performance. Happier still that even with removing the thimbles, which are commonly thought of as a ‘must have’, nothing bad was seen.
So we made a set and fitted them to the boat. Some before and after photos for interests sake.
The photos show the fibre line being reeved onto the pulpit leaving no sharp edges at all nor risk of something undoing unexpectedly and lashed onto the pushpit, and the bottom line going through the stanchion. Yes the lashings needed tidying up but note it has 6 full turns and is a 2mm Spectra cored braid. That is to up the strength in the area we found as the weak point. The top lines did have the white tube put on them at the owner’s request for comfort reasons.
The yachts owner is a very knowledgeable sort of a dude and is aware of the testing taken place and why. He has also been informed that if a line suddenly goes slack it is possible the core has failed so he has some but a reduced strength line left to get home with. He has been told to keep us informed with how they are going and the moment he thinks something may not be right, even if it’s only a suspicion and nothing obvious can be seen. So this will be a good boat to see how they pan out over time when used extensively, the boat is used a lot for both racing and cruising. We will monitor this as time ticks over like we do with a few other boats for similar reasons. The exact same line and methods will be used on the writer’s own boat.
Written by Grant Macduff on 10 March 2012
Testing undertaken 2-3 weeks earlier.
Some interesting factoids from all of this.
Weight – The old wire line set on this boat weighed a total of 2890 grams. The full replacement set done in fibre weighed 680 grams. In both totals are 160 grams for the 2 pelican hooks on the transom lines. The 2 hooks are the only metal components in the new set of lines.
Looks – From a short distance it’s near impossible to see any difference. On closer inspection many probably wouldn’t notice then either but those that do have used the word ‘sexy‘ to described the new lines. They have been advised ‘sexy’ isn’t an YNZ requirement.
Cost – To replace the full set on this boat using wire would be approximately $550 to 600. To do the same using the fibre line we did and the metal free method we did $650 to 675.
The time required to make either a wire or a fibre set would be very similar, maybe a smidgen longer with the fibre but not by much.
It takes as many cold beers to fit a set of fibre lines as it does a set of wire lines.
Disclaimer – My spelling and grammar can be crap so watch for that. Feel free to blame Wakatere Boating Club for putting in dingy lockers, which my Sunburst was kept in, half way between home and boring English class.
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