Dyneema Lifelines

Mulligan

Member
170
57
San Pedro
Lifelines fail at the terminals 

almost always bad engineering 

lifeline. terminals must articulate ...toggle and tee .. or the stud will  bend , fatigue and fail 

the  pictured fabric lifeline termination is poor 

the stud will bend and fail 

View attachment 440614
I did this.  It was for a for a friend who is a retired yachtsman who has more miles on the water than 95% of the people here!  He and I discussed the pros and cons of the project. He was in the South Pacific and his vinyl coated wire lifelines were bleeding rust.  There were several factors in the decision to go with Dyneema.  One of the reasons I agreed to do it was that nobody will be hiking on these lifelines!  His Genoa and staysail are high clewed, and don’t touch the lifelines.  The lifeline holes through the stanchions are smooth, but we added chafe protection as an extra step.  It’s on a heavy 56’ cruiser, with an electric furler for the Genoa and a line furler for the Staysail.  When offshore, nobody leaves the cockpit without being harnessed and clipped in!   The studs are 1/4”, and were assembled with thread lock.  Aft of the gate is a sold rail.  I don’t loose any sleep over this job!  
 

All of this said, I don’t like Dyneema lifelines on raceboats, and agree with the revision of the rules to prohibit them!  

 

Rain Man

Super Anarchist
7,181
2,049
Wet coast.
All of this said, I don’t like Dyneema lifelines on raceboats, and agree with the revision of the rules to prohibit them!  
They are only prohibited in SER Offshore and Coastal, not Inshore or OSR Cat 4.   I used them for years without problem and would do so again, with proper care and frequent replacement.  It comes down to your ability to correctly splice vs. the quality of the rigger's swaging machine.  I had a local outfit refuse to build me SS lifelines because they didn't trust their swaging machine.  

 

slug zitski

Super Anarchist
6,179
1,210
worldwide
I did this.  It was for a for a friend who is a retired yachtsman who has more miles on the water than 95% of the people here!  He and I discussed the pros and cons of the project. He was in the South Pacific and his vinyl coated wire lifelines were bleeding rust.  There were several factors in the decision to go with Dyneema.  One of the reasons I agreed to do it was that nobody will be hiking on these lifelines!  His Genoa and staysail are high clewed, and don’t touch the lifelines.  The lifeline holes through the stanchions are smooth, but we added chafe protection as an extra step.  It’s on a heavy 56’ cruiser, with an electric furler for the Genoa and a line furler for the Staysail.  When offshore, nobody leaves the cockpit without being harnessed and clipped in!   The studs are 1/4”, and were assembled with thread lock.  Aft of the gate is a sold rail.  I don’t loose any sleep over this job!  
 

All of this said, I don’t like Dyneema lifelines on raceboats, and agree with the revision of the rules to prohibit them!  
A high load situation for top  lifelines   is when tied alongside a wall with Onshore wind and a rising tide 

the fenders and fender board become trapped and heavily load the life line as the boat rises 

additionally,    when a human stands on the lifelines,  it’s seldom in the middle of a span.. their foot is almost always on top of the stanchion   head , stud assembly 

 

Rain Man

Super Anarchist
7,181
2,049
Wet coast.
A high load situation for top  lifelines   is when tied alongside a wall with Onshore wind and a rising tide 

the fenders and fender board become trapped and heavily load the life line as the boat rises 

additionally,    when a human stands on the lifelines,  it’s seldom in the middle of a span.. their foot is almost always on top of the stanchion   head , stud assembly 
Never let the crew tie fenders or fender boards to dyneema lifelines, or stand on them.  If switching to dyneema lifelines it is necessary, and it isn't hard to get used to.

 

DDW

Super Anarchist
6,535
1,094
^^ But especially in that case, isn't it better to be standing on deck, and bend over the lifelines?

 

sinker

Member
62
3
hmmm:

World Sailing OSR's = dyneema allowed for multihulls and cat 4 monos.  Only SS for Cat 0,1,2,3, monos. Local races and national authorities can modify that, but that's the baseline world racing standard.

There are in fact a few knots which will not slip in dyneema (like the water bowline and the estar).  But you want to use all splices in dyneema lifelines (in fact splices are requited by the WQ OSRs).  Don't use Brummel's, they weaken the splice and make it easier for DIY to screw it up. Pretty much no-one in commercial heavy lifting, where consequences are serious and stuff is actually proof tested uses Brummel's.. Find some instruction on lock stitching the bury and do that - just be careful, dont pull the stitches too tight, dont distort the weave and dont split strands.

Lashings at one end are the usual/normal way to adjust length and tension.  There are better and worse lashing techniques - the ones used by most 'yacht-ies' (and most yachting riggers) happen to be are near the worse end. But if they are made over strength it does not matter.  Just realize that the strength of the lasting is NOT = number of legs times cord strength.  It is way lower than that because of uneven tension on the legs.  Testing of actual lashings suggest you should assume only half that strength.  The WS OSR's do require the lashings to be replaced every year - and they cannot be longer than 100mm.

There are two primary failure modes - being cut by rough passages thru the stanchions and being burned by sheets zinging out over them.  The later is more a concern on bigger high performance boats - the crew on Comanche refused to use dyneema for that concern.

The OSR's do state minimum diameters - and they refer to the core alone.  So for instance if you are using a double braid like WR2 they core alone needs to meet these minimums.  And these are minimums - for the top lifeline in particular using a few mm bigger would be quite smart in most cases.
So for a product like WR2 which Max R posted a pic of up thread, how is an inspector supposed to measure the core of a line that is fully covered?   Guessing is not measuring

 
Last edited by a moderator:

estarzinger

Super Anarchist
7,624
1,010
 how is an inspector supposed to measure the core of a line that is fully covered? 
I actually remember that question came up when dyneema was being debated, and there was an answer, but I dont remember what it was (Chuck H or Stan would know).  Since dyneema is now not used for monos 0,1,2,3 the inspection question probably does not come up much.

 

Pilott

New member
18
6
Texas
I have what may be a dumb question: given possible chafe & UV degradation issues with dyneema lifeline, would it be a good idea to use 3/8" (1/4" ID) polypropylene tubing as a cover over the full length? I thought it may give a better "feel" to the line, as well

 

Rain Man

Super Anarchist
7,181
2,049
Wet coast.
I have what may be a dumb question: given possible chafe & UV degradation issues with dyneema lifeline, would it be a good idea to use 3/8" (1/4" ID) polypropylene tubing as a cover over the full length? I thought it may give a better "feel" to the line, as well
It won't be as nice to lean on for the crew, and you would have to cover the splices as well somehow to completely solve the UV issue, but sure, why not?  This assumes you are using some kind of solid tubing.  Have you worked out a way to get the line through the tubing? 

Split tubing (aka shroud covers) won't work because the tubing will separate from the line as soon as you lean on it the wrong way, unless you also tape it for the entire length.

 

Pilott

New member
18
6
Texas
Thanks Irrational14 : Duh - I meant to type polyethylene - but I suppose I could use polyurethane, or nylon instead.

Regarding the crew leaning on the lifeline : possibly not the best practice anyway, and should be discouraged :D

I had thought to use solid tubing, and thread the dyneema down it before splicing the ends. Thread it using a pull line? Thread the pull line through the tube using a ferrosteel needle on the thread and a magnet on the outside of the tube? 

Short lengths of larger tube at the ends for splice covers?

 

slug zitski

Super Anarchist
6,179
1,210
worldwide
It won't be as nice to lean on for the crew, and you would have to cover the splices as well somehow to completely solve the UV issue, but sure, why not?  This assumes you are using some kind of solid tubing.  Have you worked out a way to get the line through the tubing? 

Split tubing (aka shroud covers) won't work because the tubing will separate from the line as soon as you lean on it the wrong way, unless you also tape it for the entire length.
Use grp or carbon tube 

smallest diameter

cute the tube length to the maximum span between stanchions 

wrap electric tape around the eye splice and dyneema lifeline  to increase diameter to match inside diameter of tube and guard against chafe 

grp tube is better ... carbon splinters when you drop a spi pole on it 

whipp the tube ends to prevent splitting 

paint or varnish for Uv protection 

avoid all that lashing and thimble crap...  like in the picture... and splice directly to the bow pulpit ... tension aft at stern pulpit 

Amidship, crew hike area ,  life line tubes are not a good idea .. don’t do it 

spi sheet burn or inside outside Genoa sheet leed  chafe  can be addressed with an extra soft cover  at the chafe zone 

60C7F862-AF89-4B06-B679-BC47EB34AFBF.jpeg

 




Top