Originally Posted by
Langball
Couldn't agree more. A proper DSV has dynamic position so it can 'hover' in a fixed position close to a hazard (rock, platform etc.) and withstand significant weather (wind, waves, current etc.) due to powerful engines and bow/azimuth thrusters. The dive bell is 'heave compensated' so the divers are immune to the heave of the vessel due to the waves. And the saturation divers can stay on the bottom for hours. The vessel would have the job done is a day or two.
The Granuaille is equipped with dynamic positioning, that is why she is on station. However the conditions on the seabed are atrocious. The tide barrels through the gap between Blackrock and Parrot rock where the wreckage is located. The senior officer of the navy dive team likened it to 'diving on a flagpole in a gale'. The divers have great difficulty staying in place. Saturation divers would equally quickly become exhausted under those conditions. If they lift the fuselage off the seabed it would immediately swing sideways in the strong current and anything that fell out would be swept away. That is why the plan was to tilt the fuselage sideways using airbags but without actually lifting it clear of the seabed, in order to search underneath it. However due to the conditions mentioned, they are now considering that a straight lift may be their only option.
Rescue 116 wreckage may be lifted in search for crew