An interesting anchor ?

[Roberto]

Quote from
http://www.jets.org/newsletter/0406/extreme_engineer.htm


“It’s essentially a gravity installed anchor,” [...] “It’s lowered to near the sea floor and released,” [...] it penetrates into the mud under its own weight. It has an attachment point that rotates 360 degrees around, which means it will still have holding capacity if you pull on it in almost any direction. [...] it dives under load, which means as you pull harder on the anchor it will continue to go deeper into the soil. That, in turn, means that it will continue to gain capacity as you put more load on it—an additional benefit of the anchor."

a bit awkward to stow, but they write they made their preliminary tests with "10" to 12" anchors in mud tanks"

 

[Scotty_Tradewind]

probably at its best in Studland Bay?

 

[Chris_Robb]

probably at its best in Studland Bay?

They should ban CQR's from Studland as they drag before they set, thats if they set at all

 

[Stemar]

They should ban CQR's from Studland as they drag before they set, thats if they set at all

INCOMING!!!!!

 

[halfway]

CQR means - Coastal Quick release

However, if you are an oil rig. releasing is unnecessary. Think about what would happen if an anchor dug so deep there was no surface effect. That would mean the boat would have to exceed the full release force to lift it. If that is beyond the buoyancy of the boat then you are stuck.

An anchor has two parts; the ability to dig and the ability to limit its depth. Without both, it is not really useful. The ability to limit its depth is based on the shank to alter the angle of the blade. The blade shape then forces the anchor to stop digging and equilibrium is reached. On a Bruce this is purely the shank to main blade angle. On the CQR it is the "ears". On a fisherman's it is the cross bar's inability to dig that causes it to rotate and the blade angle changes.

This monster does not have a long fixed shank, so the whole thing acts as a plane trying to fly to the centre of the earth. Just like a kite on a string.

Hence why there are two types of anchor, and why most anchor tests are irrelevant.

 

[Boomshanka]

Would need to beef up the bowsprit a bit

 

[Roberto]

However, if you are an oil rig. releasing is unnecessary.

my curiosity: what happens when an oil rig is moved ? do they cut the cables and abandon the anchors on the sea bottom ? or try to release them ?





fascinating stuff, I once met a guy who worked on one of those ships which lay pipelines, his was from Algeria to somewhere in southern europe, he told that they simply kept adding pipe segments one after another, when they needed to stop they simply plugged the pipe and let it fall on the sea bottom, the following day they re-surfaced it, unplugged it and kept on adding other segments
Sounds logical, nevertheless fascinating to hear, he talked and waved hands like a child with plenty of lego to play with :smile:

 

[vyv_cox]

fascinating stuff, I once met a guy who worked on one of those ships which lay pipelines, his was from Algeria to somewhere in southern europe, he told that they simply kept adding pipe segments one after another, when they needed to stop they simply plugged the pipe and let it fall on the sea bottom, the following day they re-surfaced it, unplugged it and kept on adding other segments
Sounds logical, nevertheless fascinating to hear, he talked and waved hands like a child with plenty of lego to play with :smile:

In my offshore days I was involved in seals for very large ball valves, such as are used in these pipelines. When the 36 inch gas line from Brent B to the beach was completed it was reverse pigged back to the platform. 70 tons of debris was recovered! Quite a bit was ex-seabed, plus welding wire, gloves, tools, you name it. Unfortunately they pigged it all through the brand new ball valve, which was thus destroyed before it had ever been used.