iainzxr
Active Member
Many thanks to all who took the time to advise on my last post ..... laying a mooring ... now the questions are ... to fit a swivel on the riser or not .... and should the riser be chain or rope.....?
More on moorings .... swivel or not ....rope or chain.....?
- Thread starter iainzxr
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Kelpie
Well-Known Member
It depends to some extent on the location and conditions.
It is unusual to be able to do without a swivel. Some people manage but IMHO you would need to be visiting the boat very regularly and sorting out any twists, or just going sailing often enough. If you do decide to go without a swivel, try to avoid using three strand rope anywhere in the mooring as it will most susceptible to unlaying when wound the wrong way.
Re the riser, chain is good for chafe resistance so it is generally a good idea to use chain for the lower part where it will be in contact with the seabed. For the part closer to the surface a good quality rope is absolutely fine, and has the advantages of lower weight, easier handling, lower cost, and shock absorption. It can even have a longer life than chain although obviously the thimbles and shackles will still be liable to corrosion.
A practical setup can be to have the swivel about half way up the riser, somewhere that you can easily pull it on deck for inspection at a low tide. The riser below the swivel can be chain, and the bit above it can be rope.
Up here on Skye most of the fishing boats are moored using 'sea steel' rope risers, and live on their moorings all year round.
It is unusual to be able to do without a swivel. Some people manage but IMHO you would need to be visiting the boat very regularly and sorting out any twists, or just going sailing often enough. If you do decide to go without a swivel, try to avoid using three strand rope anywhere in the mooring as it will most susceptible to unlaying when wound the wrong way.
Re the riser, chain is good for chafe resistance so it is generally a good idea to use chain for the lower part where it will be in contact with the seabed. For the part closer to the surface a good quality rope is absolutely fine, and has the advantages of lower weight, easier handling, lower cost, and shock absorption. It can even have a longer life than chain although obviously the thimbles and shackles will still be liable to corrosion.
A practical setup can be to have the swivel about half way up the riser, somewhere that you can easily pull it on deck for inspection at a low tide. The riser below the swivel can be chain, and the bit above it can be rope.
Up here on Skye most of the fishing boats are moored using 'sea steel' rope risers, and live on their moorings all year round.
iainzxr
Active Member
That all sounds good and makes sense ... the boat is also to be on the West coast .. but .... what on earth is sea steel rope riser?
lw395
Well-Known Member
Swivels in the riser are often unreliable.
You can have the swivel above the buoy or under the buoy.
If above, you need a through-rod buoy which is utterly trustworthy.
But I found this to be the best solution for me on a mooring which rotated every tide.
Rope risers may be prone to damage from RYA/seaschool/random twunts lassooing your mooring.
You can have the swivel above the buoy or under the buoy.
If above, you need a through-rod buoy which is utterly trustworthy.
But I found this to be the best solution for me on a mooring which rotated every tide.
Rope risers may be prone to damage from RYA/seaschool/random twunts lassooing your mooring.
lw395
Well-Known Member
Sea steel is a brand of rope sold by Gaelforce and probably others.
VicS
Well-Known Member
A couple of useful pdfs from Chichester harbour
http://www.conservancy.co.uk/assets/assets/guide to layings a drying mooring 2013.pdf
http://www.conservancy.co.uk/assets/assets/mooring leaflet_2011.pdf
My Chichester harbour mooring consists of a concrete sinker, with about 12 ft of very heavy chain cast in, a riser chain and a pick up buoy on about 14 ft of rope.
There is no fixed floating buoy to chafe the topsides, no swivel and no rope other than on the pick buoy.
http://www.conservancy.co.uk/assets/assets/guide to layings a drying mooring 2013.pdf
http://www.conservancy.co.uk/assets/assets/mooring leaflet_2011.pdf
My Chichester harbour mooring consists of a concrete sinker, with about 12 ft of very heavy chain cast in, a riser chain and a pick up buoy on about 14 ft of rope.
There is no fixed floating buoy to chafe the topsides, no swivel and no rope other than on the pick buoy.
iainzxr
Active Member
Thanks for that ... I'll check it out..... at Gaelforce. I haven't heard of the swivel above the buoy but I suppose it's easy to keep an eye on it. How can lassooing your buoy damage your rope riser?
afterpegassus
Well-Known Member
Yes you have if you bother to read posts from those who care to offer assistance.
Kelpie
Well-Known Member
IME swivels on top of buoys are very prone to rusting up. Those located further down the rise may actually encounter less oxygen and last long, but of course are more difficult to inspect.
afterpegassus
Well-Known Member
Not if they're stainless.
alahol2
Well-Known Member
These guys... http://www.boatgeardirect.co.uk/riser.html
will make up seasteel risers to your own spec. They are very helpful if you phone. They delivered my 32mm polysteel risers for a fore and aft mooring within a week.
Just a satisfied customer.
will make up seasteel risers to your own spec. They are very helpful if you phone. They delivered my 32mm polysteel risers for a fore and aft mooring within a week.
Just a satisfied customer.
iainzxr
Active Member
Reading all the posts and understanding them .... for the inexperienced .... can sometimes be a little daunting .... and I can assure you I do bother to read ALL the posts .... understanding them is another matter. My inexperience in this matter is the reason I raised the subject on here, and I'm looking to learn from others expertise.
afterpegassus
Well-Known Member
A lot of valuable information from a spread of forumites has been offered to you in relation to the two mooring threads you have recently started. If this is all too much to digest, then surely the best advice in these posts for you, is to get a contractor local to your chosen location?
William_H
Well-Known Member
Stainless can cause a lot of trouble with galvanised iron shackles etc. If you go stainless then you really aught to go stainless through out. Or only touching really large GI parts.
Yes a swivel is IMHO a vital part of a swing mooring. As said if it is up high where you can clean it free it and inspect it so much the better. Some swivels have a ball operating inside a cup such that you can not easily see how much wear has occurred on the ball and cup. beware! olewill
Neeves
Well-Known Member
Ours are similar, concrete block with heavy steel 'U' shape cast in. 10' of massive links, maybe 200mm long links of about 40mm wire (recycled from the mining industry), then another 10' of 25mm chain (called a sweeper chain, sweeps across the seabed). Then swivel (it effectively sits on the seabed), then floating rope, 3 strand, from seabed to spliced eye that attaches directly to yacht. The rope must be about 13/14m. Small floating buoy, simply a marker. Various shackles to connect everything together. Where the 3 strand rope comes over the bow roller - reinforced with plastic hose.
The rope lasts forever. The sweeper chain and swivel 3 - 5 years. We have it serviced annually - when they lift everything up and inspecOur mooring is in 10m, we have 2m tides. I suspect the chain could be shorter in a shallower mooring.
Jonathan
Davegriff
Well-Known Member
The use of a swivel is usually recommended, unless as somebody else says, if the boat is in regular use there's no time for the riser to get overly twisted.
However it does also depend on where the mooring is. My own UK mooring just happens to be in a spot where the majority of boats actually swing back and forth on the tide rather than round and round, so it's rare to get a tangle. I imagine there are other similar moorings where the use of a swivel would be unnecessary, and swivels will always be a weak point to a certain extent.. Ask others nearby what they use.
For what its worth, I also always use a heavy rope riser (with heavy bottom chain of course), because I find it lasts far longer than chain, and IMHO gives less snatch in heavy weather (boat remains afloat most of the winter).
However it does also depend on where the mooring is. My own UK mooring just happens to be in a spot where the majority of boats actually swing back and forth on the tide rather than round and round, so it's rare to get a tangle. I imagine there are other similar moorings where the use of a swivel would be unnecessary, and swivels will always be a weak point to a certain extent.. Ask others nearby what they use.
For what its worth, I also always use a heavy rope riser (with heavy bottom chain of course), because I find it lasts far longer than chain, and IMHO gives less snatch in heavy weather (boat remains afloat most of the winter).
ghostlymoron
Well-Known Member
I always use a swivel. On adjacent (drying) moorings where a swivel hasn't been used or has seized up, the chain is very soon wound up reducing its length, flexibility and putting unfair strain on the links. I don't think anyone uses rope risers in my location my current set up is two anchors, heavy ground chain, swivel, lighter chain riser, large buoy, lighter chain to pickup buoy. When I come to renew it, I'll consider dispensing with the large buoy and having just rope from the end of the pickup chain to a small pickup buoy.
vyv_cox
Well-Known Member
When we had a mooring on the Menai Strait we always had a swivel, between the join between the two ground chains and the riser, i.e. almost on the seabed. It was quite common for the boat to make at least two revolutions per day in this very tidal place.
Kelpie
Well-Known Member
Interesting to see that some people have had success with a swivel at the riser/ground chain join. I would have thought the swivel would last longer if kept off the bottom, as small particles would presumably get into it and cause accelerated wear. However the higher up the riser you put it, the more oxygen there is to cause rust, so perhaps it's a case of horses for courses.
Neeves
Well-Known Member
Our seabed swivels fail where the ring of the swivel rubs the shackle that joins it to the sweeper chain. As you say it suffers from abrasion - but its not actually the swivel mechanism that fails. None of the seabed components are galvanised - it would wear off too quickly to be useful.
Jonathan
Jonathan
