How do they anchor weather bouys in 4000m ?

[shmoo]

Looking at charts planning summer trip...

Just noticed on my chart of Bay of Biscay that there are buoys (I guess wx buoys, since nothing to hit) in 4000m of water.

Now, assume chain weighs about 3k/m and breaks at about 5 tons. 4000m of chain will weigh about 12tons and will break under its own weight. I know the water will provide some buoyancy, so say 10 tons - it will still break before you have paid out half way to sea bed.

Have I got the sums right?

I assume they must use something much lighter than chain for same strength - why don't I use that for my anchor warp?

 

[Stemar]

"why don't I use that for my anchor warp?"

I'd guess it's because the steel hawser they use needs to be on a drum 2m in diameter to pay out properly. The experts will probably correct me on the diameter, but I'd bet it won't go down!

I'd love to be able to afford a boat with a big enough anchor locker to take a 2m diameter drum (plus cable) plus anchor plus winch plus...

Wouldn't want the boat, just want to be able to afford it /forums/images/graemlins/smile.gif

 

[shmoo]

No, I don't want to anchor in 4000m I just wanted to know what they used!

 

[landaftaf]

they use very expensive lightwieght wire rope with 'spring buoys' (floatation buoys affixed to the riser wire)

 

[shmoo]

Ok, I see. Can't do that in 20 m of water then.

Thanks

 

[billcowan]

Spanish trawlers use wire to anchor, looks dead funny, like their using string as anchor warp!

And I'v seen Italian pot markers in 150M - thats a big investment even in polyprop rope.

 

[Ships_Cat]

Surely, must be Spade anchor, 10:1 scope cable which must be nylon or the anchor will break and not be guaranteed /forums/images/graemlins/smile.gif.

John

 

[cliff]

[ QUOTE ]
Surely, must be Spade anchor, 10:1 scope cable which must be nylon or the anchor will break and not be guaranteed /forums/images/graemlins/smile.gif.

John

[/ QUOTE ]Ha, Ha, Hmmmm.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[john_morris_uk]

It might not occur to most people that submarines only worry about hitting a couple of things when dived and in deep water. One is uncharted seamounts, and the other are the cables that secure deep sea bouys... Fortunately, there aren't many of either to run into, and the bouys are usually charted.

 

[fishermantwo]

[ QUOTE ]

And I'v seen Italian pot markers in 150M - thats a big investment even in polyprop rope.

[/ QUOTE ]

Most fish traps around here are in 200m of water, thats why trap rope comes in 330m coils. When I drop line I use 700 to 900m of polyprop

 

[hylass]

[ QUOTE ]
Surely, must be SPADE anchor,

John

[/ QUOTE ]

Thanks John for the free advertisment.. /forums/images/graemlins/smile.gif

 

[cliff]

[ QUOTE ]
Thanks John for the free advertisment.. /forums/images/graemlins/smile.gif

[/ QUOTE ]It is well seeing English is not your mother tongue says he tongue in cheek.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[Ships_Cat]

/forums/images/graemlins/smile.gif

John

 

[Andrew_Fanner]

4000m. Crivens. That's about as deep down as Titanic, at abyssal plain level.

 

[DJE]

Can't they use nylon, terelene or similar? If you use a fibre with about the same density as water then surely it weighs nothing when submerged. Or is stretch too much of a problem with that length of synthetic fibre?

 

[Ships_Cat]

They commonly do.

John