Jaguar568
N/A
What are the thoughts on having a swivel with a swinging mooring ? The. Swivel is the weakest link on the riser chain as we know to our cost .
necessity of a swivel on a swinging mooring as it’s the weakest link ?
- Thread starter Jaguar568
- Start date
Seajet
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I did wonder about this years ago but my aerial shots of the club moorings at low water show hull marks 360 degrees all around the mooring, not the two postions for flood and ebb as some thought.
So aboat left for too long ( highly variable ) without a swivel will wind up the chain and mooring sinker as a spanish windlass.
Our club revised the moorings ( half tide on deep mud ) so now the bottom chain and riser from the sinker go to large buoys which stay in the water - then the seivel on top of this buoy and a chain to a pickup buoy.
We've had this arrangement for years now and it works - and a bonus is the swivel is out of the mud and grit to wear it.
I agree the swivel is usually the weakest link so I always fit the most humungous sized swivel I can, and inspect it and all the chain and moused shackles several times during the season.
So aboat left for too long ( highly variable ) without a swivel will wind up the chain and mooring sinker as a spanish windlass.
Our club revised the moorings ( half tide on deep mud ) so now the bottom chain and riser from the sinker go to large buoys which stay in the water - then the seivel on top of this buoy and a chain to a pickup buoy.
We've had this arrangement for years now and it works - and a bonus is the swivel is out of the mud and grit to wear it.
I agree the swivel is usually the weakest link so I always fit the most humungous sized swivel I can, and inspect it and all the chain and moused shackles several times during the season.
Kelpie
Well-Known Member
It's possible to eliminate the swivel but only if the boat is very regularly checked. The risk of the riser twisting likely depends on the wind and tide conditions at the mooring.
I once heard of a boat that spent seven years on a mooring without leaving. I don't know if there was no swivel at all, or if it was simply seized up, but a new bow roller was required due to the damage caused by the riser shortening up.
I once heard of a boat that spent seven years on a mooring without leaving. I don't know if there was no swivel at all, or if it was simply seized up, but a new bow roller was required due to the damage caused by the riser shortening up.
webcraft
Well-Known Member
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I've kept a boat on a swinging mooring for 16 years with no swivel.
No issues.
- W
I've kept a boat on a swinging mooring for 16 years with no swivel.
No issues.
- W
crewman
Well-Known Member
If the boat is taken off the mooring to go sailing does the chain unwind?
Jaguar568
N/A
We are renewing riser chains on a trot of 5 and 3 independent moorings . On 2 of the trot moorings the riser buoys have gone so until our diver goes down we don’t know if it was the swivel that was the weak link. I agree with Seajet use the largest swivel possible . I bought a 12 ton rated 19mm swivel but it still doesn’t look heavy enough for our 5 ton 29 ft Birchwood cruiser, I think there’s going to be a lot of experimenting with the setup to get to our satisfaction . ��
Jaguar568
N/A
We tried 1 mooring without a swivel for 2 years ,so far no problems
CAPTAIN FANTASTIC
Well-Known Member
Never used swivels on any of my swinging moorings and never had any problems apart from the odd occasion where there were a few twists on the strops.
Poignard
Well-Known Member
If I left a boat unattended on its moorings for so long that twisting caused a problem, I would have to question why I had the boat at all.
neil_s
Well-Known Member
No swivel in my mooring. No problem with the chain twisting up. Maybe it's a location thing? I am in a tidal creek that runs North - South and the prevailing wind is Westerly. I also have a steady, heavy older boat with some grip on the water. I have observed the antics of some modern lightweight flyers in wind over tide and would not be surprised to find them tying the mooring into knots.
peteK
Well-Known Member
Never had a swivel on a swinging mooring,now and again a few twists but easily sorted.
D
Deleted member 36384
Guest
I would imagine that a mooring that twisted, would also untwist because the dimensions of the variable are not constant in themselves or in combination. There will regularly be times when the variables allow the mooring to untwist.
Seajet
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Maybe one might imagine that, but certainly at our club the boats definitely twist up the chains if the swivel doesn't do its job - as personal snags prevented me even getting aboard much this year, a friend who lives a lot closer to the boat checked the swivel, chain ( and shackles, not broken into etc ) for my and other peoples boats whose owners live a distance away.
lw395
Well-Known Member
Some areas in Portsmouth Harbour, a swivel is absolutely essential, the current rotates the boat the same way every tide.
No question.
If you are lucky enough to know you don't need a swivel, don't have one.
If you need one, or are not sure, fir it under the buoy where it can be inspected and make sure it's big enough.
Sometimes you can get away with a swivel above the buoy, if you moor on a short strop with the buoy hauled up to the bow.
There is not much excuse for a swivel failing.
No question.
If you are lucky enough to know you don't need a swivel, don't have one.
If you need one, or are not sure, fir it under the buoy where it can be inspected and make sure it's big enough.
Sometimes you can get away with a swivel above the buoy, if you moor on a short strop with the buoy hauled up to the bow.
There is not much excuse for a swivel failing.
Neeves
Well-Known Member
Swivels on anchor rodes and on moorings are different do not confuse the failure of a mooring swivel with the ones sold in chandlers for attachment to the rode. The swivels in the rode can be the weakest link - the swivel in the mooring can be the strongest (and have the longest life) as you can minimise abrasion and maximise size of the swivel on a mooring.
On a mooring 'failure' will be caused by abrasion in combination with corrosion. There is not much you can do about corrosion but keeping components off the seabed and maximising size will reduce abrasion.
A mild steel, G30 swivel will have a shorter life than a G70, 80 or 100 swivel - higher tensile steels are more abrasion resistant - higher tensile steels components cost more.
Its a waste of time using galvanised components on the seabed - the galvanising will disappear in a very short period of time. There would be benefit in have galvanised components if there was no, or minimal, abrasion.
Welding the components, swivels and shackles will be more secure (but then you need to cut them off when you service).
Jonathan
On a mooring 'failure' will be caused by abrasion in combination with corrosion. There is not much you can do about corrosion but keeping components off the seabed and maximising size will reduce abrasion.
A mild steel, G30 swivel will have a shorter life than a G70, 80 or 100 swivel - higher tensile steels are more abrasion resistant - higher tensile steels components cost more.
Its a waste of time using galvanised components on the seabed - the galvanising will disappear in a very short period of time. There would be benefit in have galvanised components if there was no, or minimal, abrasion.
Welding the components, swivels and shackles will be more secure (but then you need to cut them off when you service).
Jonathan
Graham376
Well-Known Member
Many swivels have a nut welded on the end of the swivel stud, to keep the two components attached. Failure point is quite often the weld rusting away and the nut coming undone - I've had it happen once.
afterpegassus
Well-Known Member
I have a swivel because I do need one at my mooring location.
It is large, stainless, and located on top of my riser where it comes through central channel in my buoy.
Very easily inspected here.
It is large, stainless, and located on top of my riser where it comes through central channel in my buoy.
Very easily inspected here.
William_H
Well-Known Member
I have a swivel in my mooring. However it does have some friction such that the 2 lines to the boat usually end up twisted by a couple of turns over a week between visits. I have seen one mooring where the strop at the top was 3 strand spliced. The twisting of the rope (no swivel) caused the 3 strand to unravel with failure of the splice imminent.
So I think a swivel is essential. And yes it does mean you can't double up on mooring components. You an only have one swivel. (more is series of course is good). Best to have swivel at top if possible above water for ease of inspection.
Beware the type with like a ball in a socket. The wear can hidden in the socket. ol'will
So I think a swivel is essential. And yes it does mean you can't double up on mooring components. You an only have one swivel. (more is series of course is good). Best to have swivel at top if possible above water for ease of inspection.
Beware the type with like a ball in a socket. The wear can hidden in the socket. ol'will
Seajet
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My mooring as I mentioned has the swivel above the big buoy, but I certainly don't pull the boat up short to it, that would put a horrendous strain on everything inc the boat.
I use 3metres of I think 1/4" topchain and make sure to renew topchains usually every three years.
As OleWill mentions one can't really double up topchain with this system*, but I do like being able to see the shackles and swivel, which are all treble moused with monel wire; the heavy riser chain goes up through a stainless tube in the midddle of the big floating buoy so there's only one shackle underwater, groundchain to riser.
* some people lacking faith in their moorings do fit standby relatively light strops if there's a top chain, or vice versa with a plan B chain if main top is a strop.
I reckon this much more likely to wind up as a spanish windlass, have seen some awful tangles and twists when people do this.
Seperate issue but I think worth mentioning, for my Carter 30 I was on different deep water moorings, one place insisted on rope strops; in light wind over tide the boat would ' sail the mooring ' and loop the strop round and under the buoy - where the razor sharp barnacles instantly started sawing at it, generally it was too rough there to do anyhing about the barnacles, I went through two heavy duty well protected strops a season - hated the place so went elsewhere.
Jaguar568
N/A
Thank you all for your input, very interesting to read the different thoughts. Now the question is ,what am I going to do ? Answer, try it without a swivel if it doesn’t work, then fit one. !