Attaching mooring strop to a buoy

[eddystone]

I'm moving to a swinging mooring where they use Hippo buoys where the swivel is on top, i.e. out of the water, and therefore stainless steel. I will follow the advice to use a stainless shackle but would you have a soft loop to the mooring strop, cow hitched to the shackle or use a hard eye? The thimble is bound to be galvanised - will that corrode through quickly attached to a s/s shackle?

 

[jdc]

Usual advice (eg from Percuil, Mylor etc) is to always use a hard-eye at the buoy end and a soft eye at the boat end. I don't see why a stainless eye can't be found, not that a galvanised one would be a real problem as it's out of the water so not forming an elctro-chemical 'cell' all the time.

Edit: here you go. Just one supplier (of many) chosen at random: http://pacermarine.co.uk/product/stainless-steel-thimble-eye-24mm

It's only 304 so it might be better to look for 316, like this one: https://www.s3i.co.uk/24mm-Wire-Rope-Thimble-Stainless-Steel.html

 

[awol]

Use a stainless steel thimble - lots available.

 

[PlankWalker]

I am very much against stainless steel in mooring gear.
Galvanised thimbles, galvanised shackles and forged swivels are the best.
If in doubt go up a size , but not stainless.
A rope strop will need changing because of chafe at the bow roller, long before any wear on the thimble.
Change the swivel every 2 years even if it looks OK because thats the weakest link and their cheap.

Plank

 

[jdc]

I am very much against stainless steel in mooring gear.
Galvanised thimbles, galvanised shackles and forged swivels are the best.
If in doubt go up a size , but not stainless.
A rope strop will need changing because of chafe at the bow roller, long before any wear on the thimble.
Change the swivel every 2 years even if it looks OK because thats the weakest link and their cheap.

Plank

I mostly agree, and in fact I use galvanised throughout in my mooring. However, as recorded in the excellent tome 'Towards zero failures in swinging moorings' (a copy of which I've just read so it's all fresh in my mind!), several contractors always use stainless swivels in the otherwise galvanised or 'black' riser assemblies, and find no discernable effect of accelerated corrosion in the non-stainless bits. And at least one contractor always uses stainless hard eyes in the strop.

 

[eddystone]

I mostly agree, and in fact I use galvanised throughout in my mooring. However, as recorded in the excellent tome 'Towards zero failures in swinging moorings' (a copy of which I've just read so it's all fresh in my mind!), several contractors always use stainless swivels in the otherwise galvanised or 'black' riser assemblies, and find no discernable effect of accelerated corrosion in the non-stainless bits. And at least one contractor always uses stainless hard eyes in the strop.

Well the point is I don't have a choice with the swivel so it seems safest to use stainless for my bit?

 

[jdc]

Well the point is I don't have a choice with the swivel so it seems safest to use stainless for my bit?

I would in your shoes, but it's not really critical in my opinion.

What you didn't say is what rope you intend to use for the strop:
- although it's harder to splice than normal 3-strand, 8-plait is generally preferred as it can't untwist should the swivel jam
- the most likely point of failure will be chafe in the strop where it passes through the bow-roller or fairlead. That condideration has led me to prefer less stretchy ropes (so they don't rub back and forth) so I use polyester or 'polysteel' rather than nylon, but not everyone agrees with me
- everyone agrees that the diameter of the rope is nothing to do with strength - 12mm would probably be adequate for that - but for resilience against chafe. Hence use a thick rope! 24mm dia is a good choice provided it'll fit through the fairlead/roller
- decide if you want the strop to float or sink. If from the top of the buoy I prefer floating as it won't then tangle under the buoy. That means 'polysteel' which is a superior sort of polypropylene.

 

[Kelpie]

Agree with JDC above.
Get the biggest rope that will fit your bow roller. I use 32mm multiplait polysteel. It's not expensive in the scheme of things. The last strop I made up cost about £70 including thimble, shackles, and rope. The previous one has been on for over two years and I will replace it at some point this season.

 

[lw395]

I found a nylon thimble lasted longer than I wanted to keep the same piece of rope.
The shackle is the weak link. The tendency of shackles to undo on a mooring is very powerful.