杏吧原创

A MARINE salvage team can now recover cargoes from wrecks in deeper water
than ever before. The secret is a lightweight 鈥渦mbilical鈥� cable that Scottish
company Deep Water Recovery and Exploration (DWRE) uses to carry a hydraulic
grab. The company says it can explore at depths of up to 11 000 metres.

Deep-sea exploration and salvaging expeditions that rely on crewed or
remotely controlled subs are expensive and can recover only a limited amount of
material. So for five years DWRE has operated from its ship Redeemer, salvaging
cargo from up to 1250 metres deep by suspending a grab on a heavy umbilical made
from steel wire (鈥淭reasure hunters of the deep鈥�,
29 June 1996, p 38).

Now the team has turned the umbilical design inside out, developing what
director Moya Crawford describes as a 鈥渃urlywurly鈥� system. Instead of external
steel cladding, the umbilical is built around a rope core made of buoyant
synthetic fibre. The cables that supply power and relay instructions to the grab
are unreeled from a spool and wind around the rope as it is paid out.

The resulting umbilical is about half the cost of traditional cables, and
light enough to be used at enormous depths without breaking under its own weight
or being too heavy for the ship. DWRE has permission to recover metals worth
about 拢7 million from a wreck 4000 metres down off the coast of North
Africa. 鈥淭here are five [similar] wrecks in our short-term programme,鈥� says
Crawford.

Crawford, who is a member of the British initiative to study the mid-Atlantic
ridge, thinks the umbilical will also allow cheaper and more rapid scientific
investigation of the seafloor. 鈥淲ithin the next five years we鈥檒l have a system
that will go down to the deepest part of the ocean.鈥�