Life of Polysteel

[pessimist]

We've used this for mooring strops for the last couple of years and are entirely happy - no signs of chafe visible. We replaced them at the end of the first season and are considering doing so again for next. The Polysteel is not expensive but I find it a pita to splice for the thimble. Any body have any idea of the lifespan of this rope. I'd like to avoid replacement but don't want to take silly risks.

 

[Graham376]

Our two* 24mm polysteel strops are 3 years old now and still looking fine. I only splice soft loops in the ends for the deck cleats.

* The two strops are actually one long length doubled, the loop is fed through the riser thimble and then the tails passed through the loop and thimble twice. The swivel is between ground chain and riser.

 

[C08]

Our two* 24mm polysteel strops are 3 years old now and still looking fine. I only splice soft loops in the ends for the deck cleats.

* The two strops are actually one long length doubled, the loop is fed through the riser thimble and then the tails passed through the loop and thimble twice. The swivel is between ground chain and riser.

That is interesting as I need to do my trot mooring strops. Can you clarify this method of connecting the mooring line to the shackle on the buoy. My apology if that should be obvious!

 

[Neeves]

We've used this for mooring strops for the last couple of years and are entirely happy - no signs of chafe visible. We replaced them at the end of the first season and are considering doing so again for next. The Polysteel is not expensive but I find it a pita to splice for the thimble. Any body have any idea of the lifespan of this rope. I'd like to avoid replacement but don't want to take silly risks.

What is the diameter of the cordage. If its 10mm it will last slightly less long as 30mm - why allow us to guess what you are doing. Who made the 'polysteel'.

A photo also helps us guess what your splices are like. It might also indicate what you mean by mooring, to a pontoon to a buoy on a swing mooring....

Jonathan

 

[thinwater]

If I wondered I would use nylon or polyester, where we know the effects of UV an fatigue.

One solution would be to pull a few yarns from the old line and break them. Multiply by the numer or yarns and divide by the % strength of the knot and you will have an estimate of rope strength. Go from there. Otherwise, I doubt you will find published information.

 

[Graham376]

That is interesting as I need to do my trot mooring strops. Can you clarify this method of connecting the mooring line to the shackle on the buoy. My apology if that should be obvious!

I don't have a shackle on top of the buoy, it's a soft one. The strops are attached to the large (US Fed) thimble at the top of the riser as I described in #2 and the buoy is also shackled to the thimble.

 

[Kelpie]

UV is likely to be what kills the polysteel. You'll see it degrading as it fades and starts to go hairy. On a really old bit you will get bits of fibre coming away as you handle it.

 

[Graham376]

UV is likely to be what kills the polysteel. You'll see it degrading as it fades and starts to go hairy. On a really old bit you will get bits of fibre coming away as you handle it.

Having used both over the past 30 years on moorings, we've found size for size, it outlasts nylon by a couple of years. Nylon can get polished and hardened as it stretches over bow rollers or through fairleads, which is often the failure point. Polysteel doesn't stretch but the ground chain acts as snubber as it lifts in strong winds/gusts.

Contrary to popular belief, some polysteel is UV resistant. I can't find the spec for our 24mm 4 strand + centre core, it's the same stuff as used on local fish farms and tuna traps. Spec here for 3 stand - Polysteel Rope 24mm (marine-ropes.com)

 

[pessimist]

Our two* 24mm polysteel strops are 3 years old now and still looking fine. I only splice soft loops in the ends for the deck cleats.

* The two strops are actually one long length doubled, the loop is fed through the riser thimble and then the tails passed through the loop and thimble twice. The swivel is between ground chain and riser.

Thanks for that. Seems I might be being over cautious.

 

[pessimist]

What is the diameter of the cordage. If its 10mm it will last slightly less long as 30mm - why allow us to guess what you are doing. Who made the 'polysteel'.

A photo also helps us guess what your splices are like. It might also indicate what you mean by mooring, to a pontoon to a buoy on a swing mooring....

Jonathan

It's 18mm on a swinging mooring - don't think I'd like polysteel on a pontoon without something like mooring springs.
I confess that I thought 'Polysteel' was a brand name so I wasn't aware there could be different manufacturers.
No photos I'm afraid - the strops are holding the boat but I'm at home.

 

[Neeves]

Polysteel seems to be used like Nylon and may be equally misused.

If its dyneema is has no elasticity, but then no rope has much elasticity when its 18mm and used for a leisure yacht - unless your yacht is huge. You don't say what is the design of the mooring and whether there is any chain to offer something to replace elasticity. If there is no elasticity, catenary then the snatch loads might be high - but you will know that.

18mm dyneema is going to last years. It will fail as result of abrasion OR UV but dyneema is fairly UV resistant but I don't think anyone has tested it over years. Dyneema is abrasion resistant but not abrasion proof. Abrasion may occur where there are steel components that rust. If there is any UV degradation (or abrasion) you will see it before it becomes a threat.

If you have recently inspected and there are no damaged fibres you are over worrying, short term. Next time you visit the boat (and I appreciate its winter so you will not be there every weekend) post some pictures, close ups of the fibres making up the rope.

Just keep monitoring as you would any mooring. I think you are working in unknown territory.

Jonathan

 

[Graham376]

Next time you visit the boat (and I appreciate its winter so you will not be there every weekend) post some pictures, close ups of the fibres making up the rope.
Jonathan

Not very close up but may give an idea of the layup, this is 4 strand with centre core 24mm. As you say, no stretch but in our case, we have 8m of 19mm chain from the concrete block to the swivel and then the riser so no shock loading on cleats. Chain + swivel = 83 kgs.

 

[Neeves]

Not very close up but may give an idea of the layup, this is 4 strand with centre core 24mm. As you say, no stretch but in our case, we have 8m of 19mm chain from the concrete block to the swivel and then the riser so no shock loading on cleats. Chain + swivel = 83 kgs.

View attachment 146021

It sounds as if your moorings are very like ours, except we have around 5m of 30mm chain (recycled from the mines), then about 10m of 19mm chain (a sweep chain), swivel, then to a rope riser. We have 1.5t of concrete at the bottom. That splice looks nice and tight - if you made it - you are good

All the terminations of our rope are inside cheap hose pipe. So the eye at the seabed is covered in hosepipe and it is part of the splice. At the surface the riser is another eye, with hose pipe and we have a bridle again with hose pipe. Our moorings sit on silica sand (quartz) and it is abrasive. But the splices, or the hosepipe, out lasts any steel on the seabed. Our riser effectively suffers no wear it simply grows a protective coating of shell which is unceremoniously removed with a machete every year. The riser lasts about 10 years.

It depends on your seabed but I'd suggest that your 8m x 19mm chain will need to be replaced after about 3 years (that's our life expectancy of the swivel, sweep chain etc) and your dyneema will outlast it factorially. Our mooring is serviced annually (and I attend the service).

This is our mooring with its 1t block, we have since added a further 0.5t. The riser rope is being held by the operator and there is newer riser rope lying on the deck. That's our cat, safely out of the way, behind the man's right shoulder. That's the heavy duty mining chain, the sweep chain is out of sight. The mooring blocks are lifted initially with the riser rope and then with successive use of hitches to the chains. Our mooring is in 10m depths and we have max 2m tides.



This is the lower end, seabed end, of the riser rope from a mooring not far from ours which had not been serviced. You can see the hosepipe at the seabed end of the riser rope, there is some wear but most of the wear is on the steel work, primarily between shackle and sweep chain. Our mooring contractor suggested such failures occur at 3-4 years.

I don't have pictures of the actual splices, never thought it would be of interest.


Historically during every strong wind event we would have yachts on the beach - failed moorings, lack of service. We lease our mooring space from New South Wales Govmt. They then instituted no service receipt, no mooring - and failures stopped instantly.

Jonathan

 

[Graham376]

We have 1.5t of concrete at the bottom. That splice looks nice and tight - if you made it - you are good

Historically during every strong wind event we would have yachts on the beach - failed moorings, lack of service. We lease our mooring space from New South Wales Govmt. They then instituted no service receipt, no mooring - and failures stopped instantly.

I always have trouble starting the splices with the 4 strand, usually 2 or 3 attempts before it looks right.

Lack of servicing is a big problem where we are, no-one seems to bother until their boat winds up on the mud flats. I always serviced my own until we were caught, narrowly escaped a €6k fine for diving, it's a nature reserve. €5k for diving without license, €1k for no flag. Pleaded ignorance of law so they asked why no flag flying to warn divers down - gotcha! They won't issue a license to recreational divers, require team of 4 commercial divers + supervisor, license from Capitania + cost of Policia Maritima presence = €900. Also of course NOTAMS and notices posting in daily papers. Got several other boats to join in and split the cost. When they service the PM mooring next to us, only one diver needed, different rules for them

 

[Stemar]

Can you clarify this method of connecting the mooring line to the shackle on the buoy

I made up twin strops with a hard eye in the middle held in by a Brummel splice and soft eyes at the ends. For a single strop, I'd use a standard eye splice round a hard eye at the chain end and a soft eye on board.

"Polysteel is a high tenacity material on the polyolefins base: 75% of Polypropylene, 25% of high-density Polyethylene."

I don't know how elastic it is, but it claims to be UV resistant. Keep an eye on the splices, especially the hard eye, but I wouldn't be surprised to see it outlast chain if it has nowhere to chafe. It also floats, which makes picking up a mooring easier.

 

[Neeves]

I always have trouble starting the splices with the 4 strand, usually 2 or 3 attempts before it looks right.

Lack of servicing is a big problem where we are, no-one seems to bother until their boat winds up on the mud flats. I always serviced my own until we were caught, narrowly escaped a €6k fine for diving, it's a nature reserve. €5k for diving without license, €1k for no flag. Pleaded ignorance of law so they asked why no flag flying to warn divers down - gotcha! They won't issue a license to recreational divers, require team of 4 commercial divers + supervisor, license from Capitania + cost of Policia Maritima presence = €900. Also of course NOTAMS and notices posting in daily papers. Got several other boats to join in and split the cost. When they service the PM mooring next to us, only one diver needed, different rules for them

Whichever way I read it - sounds expensive. I'd be looking at other locations.

Jonathan

 

[Graham376]

Whichever way I read it - sounds expensive. I'd be looking at other locations.
Jonathan

Not expensive overall. I paid €1,500 for the mooring in 2007 or 8 and it's cost me roughly €500 over the years in replacement chain, risers etc., and of course the one off €150 for my share of the only professional service when the chain (I supplied) was replaced. No harbour/mooring dues to pay. No need to dive again for a while, I can haul the swivel up at low water and replace if necessary.