mooring shackles & Gal. chain

Discussion in 'All Things Boats & Boating' started by Mychael, Sep 28, 2008.

  1. Mychael
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    Mychael Mychael

    Could not think of anywhere else to post these questions so throwing it up for you guys.
    I may have mentioned sometime in the past that I keep my boat on a swing mooring in a bay.
    I hate it and don't like being there but for the moment it's the only option available to me.

    It's often rough with lots of wave/tide motion not to mention the wake coming from all the power boaters that have no respect for laws or common curtesy and pass through the mooring area at high speed.

    It's a constant battle to keep all the mooring tackle intact.
    Anyway enough of the rant and to the questions at hand.

    1/ Ok it would seem simple enough but I cannot keep the 'd' shackles secure, no matter what I try they work loose and I loose either floats or chain and it's getting damm expensive.

    My last attempt was stainless steel shackles with a shank bolt replacing the original shackle screw pin, the bolt gets screwed right through the shackle, I then put a nylock nut on the end of the bolt thread, I then drill the bolt and put a stainless steel split pin ahead of the locknut.

    One would think that should do it, but in a matter of months the split pin has disappeared and the locknut has loosened enough that I can get a full turn or more to make it tight again. Is it me or gremlins? Practical suggestions needed.

    2/ Chain, I've been using galvanised chain but it is corroding to the pitted stage in what I think is a short time, say 6 months.. Suppliers have said to me that the quality of the galvanising on chain now is very poor quality compared to years ago.
    Is this true? Is this another symptom of globalisation /offshore production and crap products.. Opinions please.

  2. TeddyDiver
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    TeddyDiver Gollywobbler

    Hammer the threads/bolt flatter in the end... Try to open to make sure it holds...
  3. Mychael
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    Mychael Mychael

    I'll try but remember I am working from a dinghy bobbing around on the water with the yacht on the end of mooring and everything in motion.

  4. Scrumble
    Joined: Aug 2008
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    Scrumble Oram 46'C MS Builder


    Go to

    Suggest you select the right size bolt through shackle.

    Corrosion causes diameter change therefore they loosen, if there is no corrosion no problem. And they are a lot stronger.

  5. Mychael
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    Mychael Mychael

    Looks interesting Tom.
    Should work out cheaper if they live up to the claims. Have you tried them yourself?
    The shackles I have been using are stainless, they are not showing corrosion but still seem to be working loose despite the measures I have tried as mentioned earlier.

  6. bntii
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    bntii Senior Member

    Is the mooring designed along proven lines- that is sufficient scope, correct long link chain of good size, shackles of correct size (one size larger than chain) and a decent pennant?

    I see none of these issues in the years I have kept a mooring but don't have the action of tides and wake where I am. Over the years I have just used the normal stainless tie wire on shackles with no failures both anchoring and in the mooring gear. Just as a note some traditional shackles use a hardwood drift pin that could be broken quickly by simply driving the steel pin out to release the gear quickly. I suppose the ideal is that the wood stop pin sees no load in normal use. I am wondering if for some reason the gear is loading up your shackle pins by applying a rotational force on them in use, or simply working the gear excessively. I use one of the large mooring balls which has the pipe cast through the ball. In use the lively action of the ball on the water really applies no movement to the shackles attaching the chain to the swivel and pennant at the top of the ball. The chain works of course and the top few feet loose galvanizing over about two years time, but the gear at top could last seemingly forever. At the bottom the anchor gear is in somewhat of the same conditions as the load/movement on the attaching shackles is damped by the chain. For a 40' sailboat I am using 5/8" long link mooring chain at 2.5x depth, 3/4" shackles and a 1" x 20' pennant. Ball I think is 28"
  7. Mychael
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    Mychael Mychael

    We work with metric measurement here but anyway.
    Initially single concrete ground weight (truck tyre size) with 5 metres 25mm ground chain,7 metres of 16mm riding chain, joined with 25-20-16mm shackles respectively. When we got dragging of the mooring we upgraded to an extra 200kg of ground weight,32mm ground chain and taking 16mm riding chain up to a 13 mm top chain to the boat where previously it terminated in rope.
    Shackles went up to 32-20-16mm respectively. Held up by 2x810mm buoy.

    It's at the top where I am having the problems with shackles coming loose and chain corrosion.

  8. alan white
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    alan white Senior Member

    I haven't seen mentioned the practice of mousing each shackle pin with stainless wire, but I mi9ght have missed it.
    Also, is there a big swivel allowing the mooring to rotate?
    Beyond that, best practices have been mentioned such as proper sizing of parts.
    I always go oversize with moorings.
    If the shackles come loose, mouse them. If the chain is corroding that's alright if you consider that the greatest wear is at the ends of the links where rust acts as an abrasive. Within a short time, that saddle area of the links is thinner and weaker than the rest of the link, so it matters little how weak the balance of the link is if it's still stronger than the end wear areas.
    Therefore, go bigger with the top chain if concerned.

  9. Mychael
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    Mychael Mychael

    Mousing= Feel I've already gone beyong that with using threaded pin in shackle, then locknut on pin, then stainless steel split pin over locknut. However have tried mousing with stainless wire, did not last all that long.

    Big Swivel = Do you mean at base of mooring or at the floats? There is one 25mm at bottom of mooring. None currently on floats.

    Chain corrosion = Just asked about that as a supplier mentioned the gal. quality is not nearly as good as it used to be.

  10. waikikin
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    waikikin Senior Member

    Hi Mychael,
    I have some experience in that I have rebuilt a very efficient mooring service lighter for a family business that has a 1/2 century + history in the mooring business & have witnessed "some" of their techniques & have laid & serviced a few moorings myself, importantly some of the moorings they lay are in exposed positions & they routinely lift the whole apparatus for inspection & replacement of parts, they do not rely on mousing or cable ties or such but use long pins that are heated to cherry red with oxy acetelyne & riveted over to leave a very generouse head that defies removal & servicing involves removal of parts by oxy cutting, they also have simple fabricated swivels of ample proportions that laugh at off the shelf chandlery, also many reputable mooring contractors will weld shut shackles on both sides of the "D or Bow", also the speed & proficiency of their opperation & marking of the mooring location means the concrete block usually lands pretty much in the same hole it comes out of so it remains in a more secure aspect to side loads also they charge well but fairly especially in regards to their reputation for a quality job. All the best with your mooring & vessel from Jeff.
    PS' the zinc galvanising will very soon dissapear & black(ungalvanised chain is often used)
  11. Mychael
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    Mychael Mychael

    Hi Jeff,
    Thanks for the info.. I reckon that would be what I should have done..When my mooring was originally put down I asked the contractor about welding the shackles but he did not seem too want to do it that way.
    For the ground chain I reckon that would have been the way to go but for the holding floats I need to keep it as something that does not need actually cutting for removal as the floats themselves are the huge blow-up types. sometimes they will get a faulty valve or worse a puncture and need replacing.
    Solid floats would be better but none come in the volume needed to hold the chain up. It's also quite deep where I am moored, about 8-12 metres as I recall, with zilch visibility under water.

  12. Guest625101138

    Guest625101138 Previous Member

    For times when I used a swing mooring I was fortunate enough to have access to used ship mooring lines. The ones I used were quite light at about 30mm in diameter and could be spliced. These had spliced loops hitched over the large sheet winches at the cockpit and ran along the deck, through rubber hose either side of the forestay at the pullpit and shackled to steel chain below the water level. The rope was long enough and chain heavy enough to ensure the chain was well below the surface most of the time. There were spliced loops with thimbles for shackling rope to swivel at top of chain.

    Galvanising does not last long - after all it is used for sacrificial anodes so the least noble of common metals. Most metals near the surface will corrode or wear rapidly. It is a hostile environment with air, salt, crustaceans, slime and water.

    I had a much lighter polyester retrieval line on a buoy connected to each rope loop. The buoy was not very big and could be stowed on the bow or in cockpit when moored.

    This mooring with 28ft yacht stood up to Category 3 cyclones on two occasions. The cyclone mooring location had no more than 1km fetch in any direction but 170kph winds are serious winds. Moored boats nearby were regularly destroyed through mooring failures.

    Avoiding heavy chain on the deck lowered the risk of damaging gel coat. The rope also has greater flexibility than chain so does not rely solely on weight of chain for shock absorbing. It also dampens any impact through wave action. I used the same rope in this set up for about 7 years in three separate locations and continued to use it for mooring once I got a pile mooring. All locations had plenty of sun exposure and this did not cause appreciable deterioration of the rope.

    So SIMPLE and HEAVY.

    Rick W
  13. Mychael
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    Mychael Mychael

    I also keep the chain off my deck. I use rated lifting webbing strap.. works a treat.

  14. MikeJohns
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    MikeJohns Senior Member

    We tend to recommend and use 2 times depth in chain and the top third and a bit is 30mm 3 strand poly which as Rick said is easily spliced for thimbles.

    All the chain lies on the bottom when the vessel is not pulling on it and you can replace and or clean the rope and swivel easily which tends to be the only bit with marine grown if the bottom is muddy. Some people use all rope and a pig.

  15. murdomack
    Joined: Jun 2007
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    murdomack New Member

    I kept my boats on a mooring when I was younger and poorer. I would put the mooring together myself and bring it to a guy who laid moorings as a second job. He was a foreman shipwright who had converted a boat for the purpose.
    The first question he asked me the first time I came in with my mooring on my trailer was about how tight I had screwed in the D-shackles.When I said they were pretty tight and had been moused, he told me that they would work loose. He re-tightened them with a pipe wrench to, I would estimate, about 120 lb/ft.
    He recommended using plastic coated garden tie-wire (the thicker variety) for the mousing and I did not see one bit come free in the twenty years I used it. I used a nylon pennant from my buoy down to the swivel. 9 metres at one location and 6 metres in a shallower location.

    I once had a boat break free on a mooring, but thankfully she was saved before too much damage was done. I used to put grease on my swivel thinking it made it work better. A huge dredger started working about half a mile away and the water was filled with sand which got picked up by the grease and the resulting paste ground the swivel right through. I moved up to a much bigger swivel and never added grease again. When my mooring got pulled up every year the swivel was as good as when it went in.

    I bought all my mooring chain and shackles from a mooring equipment supplier. They supplied chain that had been used in coal mines and it lasted for years. I never saw any galvanised equipment in their yard.
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