Shock absorbers increase capability of dive bell system

Paul Boughton

Red Marine has developed and delivered two shock absorber systems to Subsea 7, a global offshore contractor.

Each system – to be installed on the Osprey Dive Support Vessel later this year – is a custom unit with a shock absorber and winch line tensioning system to enhance the protection of the dive bell and handling system during launch and recovery operations.

The shock absorbers are designed to significantly reduce any shock loading on the lift winch wire caused by the differential motions of the vessel and the diving bell. In operation, a maximum acceptable line tension is set and once this value is reached a shock absorbing cylinder extends releasing extra wire length - up to 3.2m - into the system reducing line tension in a controlled manner down to an acceptable level.

Further to this, an advanced slack management capability ensures wire tension will stay above a minimum acceptable level if the vessel and bell move towards each other, reducing the risk of snatch loadings on the system.

Certified in accordance with stringent DNV codes for diving launch and recovery systems, each dive bell shock absorber system weighs 4.3 tonnes and has been manufactured using Red Marine’s proven supply chain.

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