Polysteel rope for moorings?

oldharry

oldharry

Well-Known Member
Joined
30 May 2001
Messages
10,075
Location
North from the Nab about 10 miles
Visit site
I was wondering if anyone has any more information on long term use of Polysteel rope for swinging mooring risers? I need to replace the riser on my mooring this winter, and am thinking of trying it. As it floats, is there not risk of fouled props at LW for example when 10ft or more of it may be on the surface?

And before anyone points me to it, Fullcircle asked the same question here in 2008 on a thread that was last resurrected in 2013. VicS mentioned its use in Scotland for fishing boat moorings just last month, but has anyone more up to date info about long term performance. How do insurance Companies view it for moorings?

I am also interested because Polysteel may be a viable alternative to the dubious and expensive Eco-Friendly-Moorings advocated for sensitive seagrass areas: British Seagrass Survey reports that rope moorings 'do much less damage' than conventional chain. If Polysteel is viable on a mooring, this could be a cheap and serviceable way round the expensive and fragile EFM issue in Studland and elsewhere.
 
Last edited:
I've now had polysteel risers (32 mm) on my fore and aft mooring for two seasons (28' 3.4 ton). They have been fine and a lot easier to work with than chain. My mooring is in relatively shallow water on the edge of the channel. If I blow toward the shore on a low spring than the boat can touch bottom (mud).
I found that the floating stern riser could foul my prop at low water so I tied a short length of chain alongside the riser about a metre below the waterline to act as a sinker. No problem since then.
Now that the weed has got to the risers they no longer float around on the surface.
The support buoy at the end of each riser only needs to be about 12"-18" diameter.
On a previous mooring I had a polyester riser of about the same diameter for 10 - 12 years and it was as good at the end of that period as it was when I laid it.
I reckon the polysteel will probably outlast me...
 
Good stuff but make sure that it isn't 3 strand as it will eventually unwind if on a swinging mooring.
pete
 
pete said:
Good stuff but make sure that it isn't 3 strand as it will eventually unwind if on a swinging mooring.
pete
Click to expand...


does that mean you are suggesting it has a memory for its unlaid state ? Or practical experience, please ?


I discussed the use of polysteel with my mooring contractor in Plymouth. Their view is that where there is a lot of abrasion near the sea bed , then steel chain is best. Moorings in a slow flow trot could be polysteel, to advantage. It would certainly make their maintenance diving easier.


FWIW I have been using a double set of mooring lines this season, on loan from a distinguished and experienced forumite. I've had to clean off the weed a couple of times - easily done by shaking them. They are difficult to get set up properly with chafing cover, hard and soft and eyes, and when I changed moorings they initially seemed to have taken a 'set' round the large cleats I have. Put under tension though, the bends straightened out and were OK for re-adjusting.

When I go for the new setup, I shall certainly use polysteel for the pennants and the joining line again, and I understand there is now a 'soft feel' polysteel available..
 
I had a 12m riser of (pretty sure 34mm) multiplait poly steel that lasted 5 seasons on an exposed deep water mooring for a 3t boat. Even after 5 years there was negligible wear. This was in waters where 16mm riser chain lasted 2-3 years. Some seasons mussels used it as a home but they were easily power-washed off.
A diver friend who installed it told me to attach a polystyrene commercial fishing buoy (the type with a hole in the middle) 2m from the ground chain to stop the riser bouncing on the bottom and a weight 2m from the top to stop it floating on the surface.
 
Having worked on moorings a lot, had tidal & deep water jobs, nowadays I would never consider a rope component to any part of my mooring - too prone to chafe.

Years ago I had a rope strop ( 25mm in plastic tubing ) on a deep water mooring owned by another club - the boat would ride up to the buoy in light wind over tide condtions, loop the strop over the buoy then the VERY SHARP barnacles beneath the buoy would saw at it - I never had a strop last half a season to be trustworthy, and freeing them from under the buoy cost the donation of a fair bit of blood - good job there weren't Great Whites around !

A chum had a nylon strop on his E-Boat, knew he needed to check her but couldn't due to a series of gales - the boat broke free and was destroyed.

I don't believe the short length of a mooring strop gives any elastic shock absorbing effect.

Chain doesn't chafe through, also it can be locked to prevent ne're do well vandals casting the boat adrift,,,

Don't bother with a bit of rope and a chain as a Plan B ' just in case ' - I have seen a lot of boats over the years where this has been tried, then the boat has been left on the mooring for weeks or even months due to unforeseen circumstances - the Plan A rope and Plan B chain twist together to form a spanish windlass, either pulling the boat's bow down or the mooring sinker up...

The mooring swivel is always the weakest link so have the biggest you can FIT, but it wouldn't overcome the rope & chain scenario.

Decide on one system and stick to it, don't dither with a bit of either; I decided on all chain - and a padlock - long ago.
 
Last edited:
I'm not sure how polysteel compares to sea steel, which is what I have as a strop (32mm multiplait). I would happily use it as a riser but when I bought my mooring gear the 19mm chain riser was in good nick so I just used that instead.

My strop is shackled to the very end of the riser, and the buoy is a few feet further along the riser. The weight of this bight of chain helps keep the strop away from the underside of the buoy and I've not noticed any mussel damage.
 
When the RNLI moored the AWB out in the open while the boathouse was rebuilt they used a webbing strop at the top, from the top of the buoy to the boat. Would webbing work underwater? Incidentally the strop was just the wrong length and the boat and, very large, buoy were out of sync, so it snatched terribly and nearly wore through, had to be lengthened. I told them at the start what would happen, youngsters these days, can't tell 'em anything blah blah chunter moan.....(but you would think they would have been wise to it).
 
sarabande Quote
"does that mean you are suggesting it has a memory for its unlaid state ? Or practical experience, please ?"



I do have practical experience of this happening with 3 strand :( we decided to try 28mm Polysteel instead of chain on some of our club moorings, 5 of them in total. On first inspection about 4 months later we found that some of them had started to unwind in places and the separate strands had then curled up into a real rats nest. Whether the Polysteel had lost strength by doing this I don't know but I suspect it had as one strand could be taking most of the weight.
We were pretty cheesed off with all the time and effort involved and that we have a lot of unused Polysteel left.
We are trialing lifting slings at the moment and they are looking much more promising.
I have been using a 5Mtr 2 ton lifting sling on my own mooring for around 5 or 6 years now with no problem, I usually replace it every couple of years.
 
Last edited:
Interesting, and thanks all for your input. My mooring is in very soft mud so the sinker simply vanishes right into it. It always worries me a little there is no chance of digging it into the firmer mud .5m down, but it has never shifted in the 10 years I have been on this mooring, nor have any neighbours using the same tackle. I have been doing my own moorings now for around 20 years, and have seen enough rope pennants fail on neighbouring boats to be sure they are dangerous and useless. But a rope riser in mud only has marine growth to chafe it it if its properly made up and installed, which is why I even consider it. I note and agree with your comment about not doubling up, Seajet, except my Insurers (Bishop Skinner) insist the mooring strop IS doubled up for winter use. So I just put a double chain from the swivel to the boat, each taken to separate mooring points on the boat. Never had to do it before - but thats what the man who will pay if it fails, says. So far it has never developed any Spanish windlass tendencies, though i have seen it happen with an undersize jammed swivels.
 
Last edited:
We have a ground chain connected to swivel connected to 36mm polysteel octoplait riser which is now 3 -4 years old. Previously the riser was 3 strand and had lasted around 8 years with no damage. If the swivel is working properly it won't unwind.
 
I've had 3 strand unwind. Caused by poor swivels. Winding up anything, rope chain or polysteel is baaad.
 
Oldharry ... I'm reading all this with interest as I am making up my first mooring. You say you have a double chain from the swivel ... can you tell me where the swivel is ... above or below the buoy. On a couple of replies to my post it was suggested the swivel should be above the buoy ... and it makes sense to me as you can easily keep an eye on what is .... as many say ... the weakest link.
 
I have tried it both ways. Swivel above is more likely to stick because it corrodes more readily on the swivel faces and during a clam period it can seize up. Swivel below is less likely to seize up, but on a semi drying mooring like mine is inclined to wear quicker because mud/sand gets in and forms a grinding paste. So on balancedi go for swivel above because its easier to keep an eye on it. Buy the biggext one you can fit - it lasts longer, and is less ikely to fail.
 
Is it just polysteel / seasteel, ie floating rope, which you are interested in?

I ask because where I have a mooring on the W coast of Scotland many of the risers, in particular the visitor's buoys, are now 28mm OD nylon and this has proved satisfactory over some years. A float is included in the sub-sea section just above the attachement to the sinker to keep the cable off the bottom, so this might do equally well for your purpose.

An aside, but by the way the risers are terminated in knots, not splices. I'm not entirely sure why that is, but one possible reason is that splices in 3-strand, aka cable laid, ropes can come undone in the event that the rope gets twisted due to a swivel jamming whereas a proper fisherman's, aka anchor, bend with the end moused to the standing part should stay tight whatever.
 
Last edited:
It could be because a knot is considerably faster to do...

Or that the rope has been sized for chafe purposes and even with the use of a knot is still plenty strong enough.
 
You must log in or register to reply here.

Other threads that may be of interest

O
South Coast - Cheap boating option
3 4 5
Replies
97
Views
3K
Chiara’s slave
Chiara’s slave

Share this page

Top