The unparalleled development of oil and gas exploration has resulted in a greater need for reliable, effective equipment by modern underwater aquanauts.

As divers often work alone, contending with poor visibility, variable depth water pressures and temperatures, there is a major need for tools that meet their demands.

Stringent demands
J D Neuhaus is among the manufacturers working in this space and central to its offering is its hoists that have lift capacities from 250kg up to 100 tonnes, while specialised units of 200 tonnes lift capacity have also been supplied for BOP handling.

"The development of subsea hoists means that underwater as well as on-deck lifting operations for a wide range of operational, maintenance and repair functions can be undertaken on jack-up rigs, semi-submersible platforms, drill ships and FPSO vessels," the company said.

It added: "Even undertaking underwater pipeline and wellhead operations down to levels of 70 metres can also be considered.

"The proliferation of offshore wind farms and wave powered generation systems has also increased the potential requirements for suitable power tools that can be safely utilised underwater. Harbour locations often require underwater work, albeit not at great depths, while lakes, rivers, dams, reservoirs and bridge building operations can also have need for similar inspection, recovery or repair operations."

Global reach
One example of JDN hoists being used in the field of underwater environments was the utlisation of its air-operated hoists that helped removed and replace a 50 ton rudder on a fully loaded bulk carrier vessel.

Following the breakdown during a voyage from Brazil to China, the ship was first towed to a safe mooring off the coast of Venezuela, where the rudder removal and replacement work was undertaken.

"Three standard air operated JDN Profi 25 tonne capacity hoists were used in conjunction for this operation, with these units being subject to full rebuild procedures after the job completion. The work was successfully undertaken at sea, without the need for cargo removal or transfer," the company explains.

Product development
J D Neuhaus has since company introduced purpose designed hoists suitable for subsea operation. These incorporate uprated performance and sealing features to withstand continuous underwater operation, even at depths of 70 metres.

These can be supplied for either compressed air or hydraulic operation, which utilise a diver-friendly pendant controller, which is compatible with constricted, gloved-hand movements.

"This controller is connected by standard length 2 metre hoses to the hoist which ensures the aquanaut, hoist and load are all located within a close working environment," the manufacturer said.