Mooring strop diameter on swinging mooring

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DanRocksOn

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I have a 34 foot boat, 6 t displacement and its going on a swinging mooring.

What diameter strop would be needed.

The cleats at the front can take 16mm but 18mm might not go through the cleat and around the horns using a spliced eye.

Assume nylon 3 strand

Any recommendations
 
On my swinging mooring I have chain from buoy up and over the bow roller to eliminate any chafe, this terminates in a loop. From this loop I have 2 large diameter, spliced 3 strand strops that go over each of the bow cleats.
 
I don't know protocols in the UK but here in Oz our swing mooring was covered by the mooring contractor's insurance BUT only covered what he supplied. I'm surprised your mooring contractor does not supply from seabed to cleats - including the 2 mooring strops.

Jonathan
 
Based in Ireland and mooring ball is dropped by a contractor on a boat by boat basis.
I have no roller or fairleads. Just cleats.
So it will be rope. Just debating if 16mm is enough
 
Chaff is the most likely issue.
Use the thickest line that'll go over your cleats.

Then add hose like chaff protection over any part that mighy rub on, for example, the toerail, or fairlead areas.

I dunno about Oz, but here the bouy, chain and sinker are provided, and boat owner is responsible for attaching and maintaing a riser from the chain to the boat.
 
I was going to feed the line thru the cleat and around the horns. Boat came with 16.m mooring lines and these fit.

With 18mm, I might only get the eye splice around the horns. Worried it might pop off
 
I wouldn't advise Nylon but polyester. This is because:

1. the greater stretch of Nylon won't have any cushioning/damping effect on a mooring strop (far too short, far too thick a rope)
2. Any stretch will increase chafe at the roller / fairlead
3. Nylon goes hard and very stiff after a year, which is a pita when you're picking it up.

Polyester keeps its flexibility and is just as strong and UV resistant. I agree with 3-strand but make sure the buoy has a working swivel.

The above assumes the attachment to the riser chain is below the buoy, in which case you want a sinking rope such as polyester. If the attachment is on top of the buoy then a floating rope is less likely to tangle, something like 'Seasteel'.

I have two moorings, one near Falmouth which is laid and maintained by Mylor yacht harbour and has the attachment below the buoy. This one's strop is polyester 3 strand. The other mooring is on the west coast of Scotland and I am responsible for its maintenance, it has a Norfloat hippo type buoy with the attachment on the top and here I use Seasteel multi-plait for the rode.
 
Neeves said:
I don't know protocols in the UK but here in Oz our swing mooring was covered by the mooring contractor's insurance BUT only covered what he supplied. I'm surprised your mooring contractor does not supply from seabed to cleats - including the 2 mooring strops.
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I don't think there is a "UK protocol" but my mooring contractor inspects what is there, and if I have asked him to replaces anything which is needed. He does seabed to cleat, but it is not unusual for the final connection to be the boat owner's job - especially when arrangements for servicing are done across a whole area and each vessel has its own specific needs. I would be very surprised if my contractors insurance covered any defect in the equipment rather than defect in his inspection process.
DanRocksOn said:
With 18mm, I might only get the eye splice around the horns. Worried it might pop off
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I think if you go through and over the horns I will be (a) too thin a line, (b) a real bugger to get off when the wind is blowing hard and its become crusty sitting out in the sun for a few weeks. Its common to use a thin line (e.g. the pick up bouy line) OXO'd over the cleat to prevent it "jumping" off. That line isn't taking any load its just stopping the main eye squirrelling free.
 
If there's no fairlead, you'll need to be serious about preventing chafe at the toerail. 16 or even 18mm would be quite small compared to any mooring I've ever set up, but maybe it's a small boat and a sheltered, summer only location.
 
I was warned off 3 strand on a swinging mooring because of the risk of cockling so went for 1 x octoplait plus 1 x chain strop. This was on the Dart through winter. The octoplait took the day to day strain with the chain as a back-up. Bulky, but we got safely through 4 winters.
 
stranded said:
I was warned off 3 strand on a swinging mooring because of the risk of cockling so went for 1 x octoplait plus 1 x chain strop. This was on the Dart through winter. The octoplait took the day to day strain with the chain as a back-up. Bulky, but we got safely through 4 winters.
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After. Eight strand Seasteel is what I've used, with lay flat hose as anti chafe through the bow roller. I used 38mm which was the biggest that would fit. Far too big for the cleats, so the eye dropped over the manual windlass.
 
Sea Change said:
If there's no fairlead, you'll need to be serious about preventing chafe at the toerail. 16 or even 18mm would be quite small compared to any mooring I've ever set up, but maybe it's a small boat and a sheltered, summer only location.
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From the OP: 34 foot boat, 6 t displacement
 
For perspective, 20mm rope min breaking load is over 6t so you could hang your entire boat off it. I doubt your cleat would hold that much. I think you could smaller with adequate chaff protection
 
DanRocksOn said:
Thanks all.

I am going with 20mm 3 strand with a splice. Will mouse it down to prevent hopping off.
Lots of chafe protection for 1 metre from cleat to protect where it might lie against boat hull

Dan
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Good call. Big rope looped over cleat is best, and was about to suggest what I think you are now proposing - use of an offcut of thin rope tied tight around the eye multiple times to ensure no possibility of coming off.
No expert personally, but like others I was thinking not nylon for this, perhaps polyester better.
One thing, how close are your cleats to the bow? Our cleats are 1,5m back which is not ideal on moorings, hence I added Osculati bollard / cleats much further forward - they can be used as a faultless for huge ropes to lead to main cleats, or as cleats for smaller ropes.
 
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