moorings

[nac]

I AM HAVING A LOT OF PROBLEMS WITH MY BOAT BREAKING HER MOORINGS.
I HAVE TRIED DIFFERENT COMBINATIONS ,LIKE COMBINATION WIRE AND ROPE . CHAINS WITH SHACKLES. ALSO SWIVELS. THE SETUP IS ,HEAVY CONCRETE BLOCK WITH HEAVY CHAIN =1"THICK LINKS THEN LIGHTER CHAIN TO BUOY AND THE RISERS TO BOWCLEAT. ALL TO NO AVAIL . THE MOORINGS IS IN A SANDY ESTUARY WITH A HEAVY CHOP IN HEAVY EASTERLYS
THE YACHT IS A 30 FOOTER APPROX. 4 TONS.

ALL REPLIES WELCOME.
NAC.

 

[Guest]

A bit more info please Nac

I am no expert on moorings, but know the feeling of being phoned up and being told that your yacht is halfway up a sea wall.

Is the chain going at the bottom shackle/swivel area or nearer the top end ? Also the scope you are using and max height on your mooring on a Spring tide would help.

Regards

 

[pete]

Put my half tide mooring down about 6 years ago no probs yet,it is in quite a strong flood I have two half ton weights 150 ft apart in line with the flood connected with 3/4 inch chain (bar size not link) in center of this chain I have 6 foot of 3/4 inch chain riser then it reduces to 3/8 chain with a swivel just below the buoy from buoy I have two strops to the boat.
all shackles are moused, the swivel is 3/4 inch, and every winter I remove the lighter chain and replace with winter riser,as my boat is ashore, I inspect shackles,swivel and strops over winter and replace as required, ground chain is mostly buried in sand but when it has apeared it is like new, If in doubt over size!. If you can get someone else to link onto your back weight for their front mooring weight so much the better.
hope this helps
pete

 

[byron]

No need to shout, typing in Caps is very bad form and is considered shouting.
I have no answer to your question other than a conjecture. Could it be that at high tide your boat is snatching? If so a bit more slack would be the answer.

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[boatone]

If it breaks something ain't strong enough or long enough. Where does it break? Same (ish) place every time? Have you calculated length of chain need to ensure enough slack even at highest high tides and then some? Is there someone else close by with similar size/weight boat thats ok? Wot is their mooring rig? Just need to carry out a systematic analysis of the problem and you will find the answer. (Presume ther's no damage to boat gunwhale is there? If there is its a sure sign snatching is probably main cause and length of chain too short. Most people use a rough rule of thumb for anchoring of 3 times depth of water for scope of chain)

boatone@boatsonthethames.co.uk

 

[steveh]

I used to have a mooring in the open sea at Selsey. We used a long length of 1" dia chain (bar dia). Attached was a 3/4" riser chain. The very heavy bottom chain takes all the snatch out which is what causes the chain to break. Another method used is to attach a mooring bouy to the riser and then the boat to the bouy. This seemed to lose the dampening effect of the heavy bottom chain. A rubber snubber fitted to the top part of the riser may also reduce the shock loads.

 

[Guest]

Re: A bit more info please Nac

Nac ..... the main agreement seems to be to question either the strength of the chain you are using and also the scope.

It is common to have the heavy bottom chain eg. 1" bar and equal to the rise of tide, then a swivel, then the lighter riser chain, eg 3/8, again equal to the rise of tide onto a buoy and strops. The strops should be adequate length to go from mooring point over the stem and just above waterline. OR even better is to .... increase the riser length to get the chain over the stem and then strop to mooring points. I would always advise minimum of two strops so that if one carries away, you have the other. Also make sure they are fastened to different points on the boat ..... I had a Oak mooring post snap off in a gale at the mooring and the second strop on the simple side mooring cleat held her !

The above has held various boats up to 30ft in Langstone harbour, conforms to Harbour Board recc'd scheme and survived gales, storms etc. All shackles were 'moused', swivel was oversize to ensure strength etc.

Have you checked your system against others near you ???? What is different .... have you bought 'Chinese chain' ???? B&Q special is NOT recc'd ..... go to a Marine Scrap Yard and buy good proper gear .... even Chandlers can fall foul of cheap chain !!!!!!

Finally ...... have you a copy of the local Harbour Board Mooring requirements / reccomendations .... most HM's issue them to clubs etc. in their area and this is based on years of experience and often on the system they use for the HM provided moorings.

Sorry if most of this sounds like 'father to son' but it appears you have a serious problem if moorings are parting .... needs to be sorted QUICK !!!!!

 

[John_Clarke]

I have experience of ex-colliery high tensile chain snapping. Have been told that this type is not good in salt water.

In addition to a chain strop from the swivel on top of a Hippo bouy (expensive but excellent) up to the cleat on the boat, I have fitted a shock absorber to this chain. This I have made from 8mm braided nylon climbing rope threaded inside reinforced PVC garden hose. I tied this to shackles at both ends using a round turn and two half hitches with the tails whipped to the standing part and covered in duct tape. The length between the shackles is about 2.5m and the chain hangs in a slack loop between them. I have allowed this portion of chain between the shackles to be 20% longer than the nylon so the chain will take the strain before the nylon will snap. The bottom shackle is attached to the swivel on top of the bouy and the top shackle is just below the bow fitting and clears the CQR anchor on the second roller.

Another thing we do is to apply oil based sealant (which is non setting) to the threads and holes in the shackles which stops corrosion and makes them easier to unscrew.

 

[Guest]

Good to see Byron waving in the e-mail etiquette!! (from one of the other forums I see he is the master (of e-mail etiquette!!))

By nature, I'm a complete slacker - I always see what everyone else has done, make sure it works...and then copy them!!!!! Do other people have the same problems? if so - how have they solved them?

Not very original but avoids re-inventing the round thing.

MM

Oops! - Praise be to Byron - You da daddy!!!!!!!!!

 

[byron]

Ooops! problem is with your last line is that it becomes a private joke as I doubt anyone here knows how that all started.
Also you forgot the or ;-) so I will hope it's the latter.


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[Guest]

Bugger!

( | )

 

[nac]

Re: A bit more info please Nac

To byron,sorry about the caps but i could not find my reading glasses at the time and could not read the text. Thanks to all who replied.
nac

 

[byron]

Re: A bit more info please Nac

No Problem Nac
I'm lost without mine, got dozens of pairs bought cheap down street markets and left all over the house and boat in strategic places plus a pair around my neck on a hawser. ;-)

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[iainmillett]

I would always ask around for the answer locally.

Weight doesn't always = strength in moorings. Correct length being most important for the tidal range.

Also around here, ground tackle tends to be iron based.

I find difficulty with my double ender with wind V tide situations.