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Old 02-09-2011, 13:29   #1
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How Much Chain Do Ships Carry ?

Not sure where to look this up, but how much chain do ships normally carry? And does it depend only on the size/draft of the vessel, or does it's mission have anything to do with it?
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Old 02-09-2011, 13:42   #2
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Re: How much chain do ships carry

On average I'd say 10 to 12 shackles on each anchor.
Each shackle = 15 fathoms, or for the newer generation, about 27 meters-
As the ship gets bigger, then larger chain is used.
My boat displaces about 6500 tonnes, and has 36mm chain (thats the diameter of the bar that the chain is formed from).
The oil rigs we work with have chain diamter of anywhere between 76 to 90mm, and you wont be handballing that stuff over the roller

Just as a foot note, ship owners like the least amount of chain, it does not earn them any revenue
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Old 02-09-2011, 13:58   #3
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Okay, so that's roughly a thousand feet for each anchor (2?). Are your anchoring techniques and scope ratios more or less the same as we use on small boats?

I noticed the Navy put to sea during Irene. Back in around '85, I was on board the Nashville, and we went out a few hundred miles to miss one off the coast of NC. That was a rough ride, even the sailors got seasick.

What do you do?
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Old 02-09-2011, 14:01   #4
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Re: How Much Chain Do Ships Carry ?

When I was in San Pedro Belize a private ship, Platinum, ran aground on the reef. They started dumping chain and after a while they floated off the reef, pulled up chain and left.
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Old 02-09-2011, 14:05   #5
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Re: How Much Chain Do Ships Carry ?

My last ship carried 14 shackles (385 metres) of cable made from 122 mm chain on each of two (18 tonne) anchors. The ship's length was 330 metres and her displacement 359,000. The deepest water in which we anchored was generally about 100 metres. Our limitation is mainly the lifting power of the windlass - as you might guess the cable is pretty heavy.
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Old 02-09-2011, 14:33   #6
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Re: How Much Chain Do Ships Carry ?

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My last ship carried 14 shackles (385 metres) of cable made from 122 mm chain on each of two (18 tonne) anchors. The ship's length was 330 metres and her displacement 359,000. The deepest water in which we anchored was generally about 100 metres. Our limitation is mainly the lifting power of the windlass - as you might guess the cable is pretty heavy.
Guessing that was a ULCC based on length and displacement.
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Old 02-09-2011, 14:41   #7
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Re: How Much Chain Do Ships Carry ?

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Okay, so that's roughly a thousand feet for each anchor (2?). Are your anchoring techniques and scope ratios more or less the same as we use on small boats?

I noticed the Navy put to sea during Irene. Back in around '85, I was on board the Nashville, and we went out a few hundred miles to miss one off the coast of NC. That was a rough ride, even the sailors got seasick.

What do you do?
Scope and technique pretty much the same, although no nylon snubbersMany moons ago, if supplying the rigs, it was common for the anchor handlers to moor to the rig, basically a meddy moor, Becasue this was common practise, we had 27 shackles of chain each side, to allow it to be done in deep water. Was quite impressive to carry out, would steam directly at the rig 5 to 6 kts, when a cable off, let brake off the anchor, and let the chain fly off the windlass, then about 50 meters from the rig, slam the brake on, helm hard over with the sticks split, and come to a stop with the stern a few feet from the rig, pick up the mooring ropes, stop engines, kettle on.




TRS, rather be at sea, hove to, safest place for most ships,
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Old 02-09-2011, 15:44   #8
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Re: How Much Chain Do Ships Carry ?

TRS - agree with Nigel - at sea and well away from land. Anchoring with heavy gear and what are actually fairly crap windlasses - we do the whole thing in gear else we are liable to lose the lot. And yes my last ship was indeed a ULCC although these days we are only allowed to call them VLCC's so we don't frighten some of the more delicate souls about.
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Old 02-09-2011, 17:19   #9
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Quote:
Originally Posted by nigel1

Scope and technique pretty much the same, although no nylon snubbersMany moons ago, if supplying the rigs, it was common for the anchor handlers to moor to the rig, basically a meddy moor, Becasue this was common practise, we had 27 shackles of chain each side, to allow it to be done in deep water. Was quite impressive to carry out, would steam directly at the rig 5 to 6 kts, when a cable off, let brake off the anchor, and let the chain fly off the windlass, then about 50 meters from the rig, slam the brake on, helm hard over with the sticks split, and come to a stop with the stern a few feet from the rig, pick up the mooring ropes, stop engines, kettle on.

TRS, rather be at sea, hove to, safest place for most ships,
That's cool. What size vessel?
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Old 02-09-2011, 18:53   #10
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Re: How Much Chain Do Ships Carry ?

I learn something every time I visit this forum. I've always heard 90 feet of chain called a "shot". Calling it a shackle makes sense as 90 feet is the distance between shackles. Now if someone asks me for a shackle of chain, I'll know what he means. Thanks guys!
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Old 02-09-2011, 20:35   #11
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Re: How Much Chain Do Ships Carry ?

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Are scope ratios more or less the same as we use on small boats?
Seems to me most on small boats use a set ratio (3:1, 5:1) for water scope to water depth. The British Admiralty method is 1.5 x the square root of water depth in metres = the number of shackles of steel chain. This is reported to be sufficient to hold a warship in hurricane-force winds. Of course less cable is often used, especially where anchoring for a short duration.
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Old 02-09-2011, 20:54   #12
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Re: How Much Chain Do Ships Carry ?

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My last ship carried ....385 metres... of cable ..
Thats why I think its insane for sailing boats to carry only 100/150 feet of chain. I carry 330 feet /100 meters.

And as Steve says the limitation is what the windlass can haul up.
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Old 02-09-2011, 21:07   #13
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Re: How Much Chain Do Ships Carry ?

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I learn something every time I visit this forum. I've always heard 90 feet of chain called a "shot". Calling it a shackle makes sense as 90 feet is the distance between shackles. Now if someone asks me for a shackle of chain, I'll know what he means. Thanks guys!
I suspect that "shot" vs "shackle" is an Americanism vs Britishism. Kinda like "fountain" vs "bubbler," or "elevator" vs "lift," or "trunk" vs "bonnet."

No worries. We'll teach 'em English if it's the last thing we do.
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Old 03-09-2011, 02:16   #14
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Re: How Much Chain Do Ships Carry ?

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I suspect that "shot" vs "shackle" is an Americanism vs Britishism. Kinda like "fountain" vs "bubbler," or "elevator" vs "lift," or "trunk" vs "bonnet."

No worries. We'll teach 'em English if it's the last thing we do.
Bang on Bash, Shackle = Shot. Found that out on my first trip to the US when the pilot called for 6 shots in the water, after a small debate, we worked out what he meant.'
As most big ships chain is made up of lengths of 15 fathoms, joined by a kenter link ( in the old days a shackle), the origin of the term shackle for 15 fathoms of chain becomes obvious
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Old 03-09-2011, 02:55   #15
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Re: How Much Chain Do Ships Carry ?

On the new V Class anchor handlers we have now we only have 8 shackles either side, if it's to deep for 8 we hit the push button anchor....
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