Deep Water Capstan

Exploration and subsequent oil and gas production in ever deeper subsea environments has created a market requirement for cost effective means of deploying tools and structures to the sea bed in a safe and efficient manner.

Modern fibre ropes exhibit near zero weight in water and overcome the self-weight issues when using steel wire especially in deeper waters. However, the use of long length fibre rope especially at high tensions requires different handling systems to wire. Parkburn has spent many years in research and development to develop the Deep Water Capstan.

The design process carried out a detailed review of current drum winch and traction winch technologies to identify the “good” and “bad” features of each with respect to fibre rope resulting in the ideal features list to be included within any new design.

• Store the rope or cable at low tension
• Modify the standard traction de-tension, tension profile within the winch to spread the work over a long section of rope to minimise fatigue and slippage.
• Ensure there is a fixed input and output from the winch with no fleeting forces.
• Compact and light weight machine while achieving a D:d ratio between cable and drum surface in excess of 35:1
• Fixed mechanical machine with simple forward reverse function
• Multiple drive options
• Cost effective

The resulting Deep Water Capstan comprises two separate drums merged and offset to each other around the rotational centreline to create a natural helix and a slightly elliptical cable path through the machine. Each drum has 16 “fingers” which provides the product bearing surface. This results in a unique binary tensioning/de-tensioning profile that spreads the work evenly through the product as it passes through the machine. After it emerges from the Deep Water Capstan, the product can be stored at low tension.

In parallel to the DWC development, Parkburn has worked very closely with Applied Fiber www.applied-fiber.com in the development of socketed fibre rope terminations to ensure the connection from payload hook to rope is carried out in a safe, compact and highly efficient manner, removing the need for conventional eye splice and additional hardware such as shackles and thimbles to connect to the payload.