What's a shackle? (big ship anchoring)

[hebdena]

Re: There\'s an International Convention on that!

I believe if my memory is correct that the makers of the film Titanic actually got the helm order and wheel movement correct. The iceberg was on the stbd bow and the order was 'helm hard a'stbd' and the wheel was turned to port. 'Tiller' helm orders were still used by White Star at this time.
Useless bit of trivia, the pin used to hold the joining shackle together is called the spile pin.
We used to hang off an anchor and use the cable for mooring to buoys in Hong Kong. Spent many a happy hour as a cadet heating up joining shackles in an attempt to remove a recalcitrant spile pin!

Regards....................Andrew

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[vyv_cox]

Re: There\'s an International Convention on that!

One of the first failure diagnosis jobs I ever did was on one of these, where users had done exactly what you describe. The steel used for these shackles is hardened and tempered, so heating them to red heat anneals the steel and reduces its strength considerably. This particular one had then failed, putting a large tanker at risk and losing its anchor. At that time losses of anchor gear cost this tanker fleet more than 0.5 million pounds sterling per year.

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[Mirelle]

Re: There\'s an International Convention on that!

Precisely so. I am idly trying to find my copy of Cockcroft and Lammerjier, which has a history of the colregs in the front. I think it was the version of the Colregs which came into force in 1930 which brought in the change in helm orders.

It was the ex-Master of the celebrated Hong Kong tug salvage tug "Taikoo" who told a story about someone mucking the helm orders up in LyeMun passage in 1930 which makes me think that was the date.

The "Taikoo" was designed by the staff of the Taikoo Dockyard, whilst interned in Stanley, and since they were a bit cut off, so to speak, they made her a steamer - probably the last steam salvage tug to be built.

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[Mirelle]

Re: There\'s an International Convention on that!

Brain started working again. It was Bill Worrall. But I still cannot lay my hands on Cockcroft and Lammerjier.

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[Equinox]

Re: What\'s a shackle? (big ship anchoring)

In anchoring terms the length of a shackle is 27.3 metres / 90 feet or 18 fathoms. The kenter lugless joining shackle consists of two parts that are pushed together and a 'stud' is placed in the middle of the shackle and held in place by a spile pin. A lead pellet is then forced in behind the pin to hold it in place and stop it slipping out.

The kenter joining shackle is normally manufactured in nickel steel and so this prevents corrosion and the two parts freezing. This allows the shackle to be broken quite easily and the spile pin is then removed using a punch and drift.

Ships don't normally have cause to break the anchor cable and the only time I have seen this happen was when I was a deck officer with the Royal Fleet Auxiliary. In Plymouth Sound the RFA ships would break their anchor cable in order to run the cable to the buoy and then secure it to the bouy with a shackle.

As far as commercial ships are concerned the anchor cable would be broken if a ship was to be towed or if it was necessary to 'hang off' an anchor.

Hope that answers your question.

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[hebdena]

Re: There\'s an International Convention on that!

I was a mere Bank Line deck cadet just doing what the mate told me to do! I suspect we were all ignorant of the effect heating metal had on it's strength, although I'm sure we never got anywhere near red hot as we were using parafin powered blow torches!

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[Mirelle]

15!

Full marks, but there are 15 fathoms in 90 feet!

Ships intending to lie to an ordinary buoy, as, commonly, in Hong Kong, and a few other places, will break the cable to do that, and hang off one anchor, or it might be done to get out from an unsafe berth if there is no opportunity to recover the anchor. A big tanker will not use her own cable to lie to an SBM; the SBM's chains are taken aboard and dropped into AKDs on the tanker's foredeck; these allow quick release in the event of an emergency, for which purpose, and to avoid overrunning the buoy, the tanker should keep her main engine at readiness.

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[chas]

Re: What\'s a shackle? (big ship anchoring)

18 (I think) berth in Malta always required both cables to be broken and attached to the buoy.

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[Guest]

90 ft / 6 ft = 15 fathoms !!

QED

<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

SBM / SPM ...... all different me old fruit !!

BUt basically agreed ....

Some companies like Chevron thought they could better the Smit Towing Bracket ........... trouble was they didn't allow for variance in chain sizes etc. Two particular vessels I used to sail on we couldn't use the patent chain systems and had to use the older 'quick-release' hooks / chains and wires to the mooring bits !!!! Why ----- because they enclosed the towing brackets in a 'box affair' to make it safer !!!! and the chain couldn't pass through unless it was EXACTLY the size quoted to the desk-bound designer !!!!


Anyway a shackle is still 15 fathoms whatever anyone says !!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

Re: Nationality and language

I was 17 yrs at sea on Merch ....... the last 11 were foreign flag ...... with more nationalities than a dog gets a sniff at !!!! On one ship - the missus and I were the only Euro's out of 14 nationalities on board !!!! We all said Shackle ...... even the Indonesian / Greek / Philipino / Yugoslav engineers !!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

Re: Fathoms?

Seaman are old farts at heart !!!!! As we have all come to know as Yachties / Ships etc. - the sea has its own language literally independent of all logic and other factors !!!!!!

Larboard and Starboard ........ now shout those in a wind and see what happens !!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

OK .... point taken BUT ....

a practical way to think is ...... (and remember that because merch are doing this day in day out, they literally don't think about it .....) if you read metres - halve it and you have approx. fathoms .......... OK so a metre is actually about 39 inch - but its close enough for practical purposes

AND remember that its only really charts that went metric - which constitutes a major but not majority part of merch life !!!!

Now a note to really get you thinking ......... many vessels - particularly tankers have to think in terms of Barrells, Cu. M, US Galls, Metric Tons in Air, Metric Tons in Vacuum, Long Tons ...... and then they can be subdivided into Gross, Nett, Total, Received, etc. etc. Onto Dry Cargo ships ..... we have Bale Capacity, Grain Capacity, Net Registered, Gross Registered .....................

Given up yet ?>?????????


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

Oh OH .....

Sea mile = 1 minute of arc of latitude ...... which becomes infinite at poles in THEORY !!!!!

Basically the sea mile is variable dependent on latitude.

The radar mile is fixed at 2000 metres

The Statute mile is fixed at 1760 yards by Elizabeth 1st of all people !!!

There is a approximate measure for sea mile based on a figure DECIDED by agreement - but to be honest I can;t remember it as it had so little to do with navigation and real life that no-one I knew ever used it !!!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

Spile pins ....

As a Cadet m'self and doing similar ........ I asked the question ....... How does such a thin pin hold all that weight ..... blah blah blah ????

Stupid Cadets, its under shear not longitudinal stress !!!!

Sorry not trying to argue with anyone - just passing on the Mates comment !!!! I must admit having also sailed on ships where we used wood pins to make it easier to knock out ...... I can understand that shear is VERY different !!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Mirelle]

oops!

Meant 100 fathoms i.e. 200 yards. And its a minute of arc of longitude, measured officially in the English Channel off the Nab Tower (funny which bits of lecture notes stick in your mind!)

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[Guest]

Blimey - I really didn\'t know that !

I know that Liz 1 decided the statute mile based on some measurement she devised that had no scientific or real base to be calculated on !!!! If memory serves me right - (some b----d other cadet stole my Navigation notes from College many moons ago and it was all in there !!!!) - she did it at Hampton Court .......... and again if memory serves me right it was actually the furlong that was quoted !!!!! Oh hell - its get even worse dunit !!!!

You know we had it all simple and then along came some scientist who mewasured the wavelength of some element and decided on the metre .......... that then got mucked about so that we now have the meter and the metre ............. another clever B then started mucking about with ships terms and all things nautical and we ended up with Draft and Draught ........................

Who started this ???????????



<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Mirelle]

Probably time we stopped!

Anyway, all who have posted here can claim to have answered Ken's question about the meaning of the term "shackle" quite comprehensively!

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[Equinox]

Re: 90 ft / 6 ft = 15 fathoms !!

You are quite right of course! 90 feet is 15 fathoms...........my typing error!

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[Guest]

No problem and no disrespect intended nm

*

<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !