UKSBSPR16200 - Containerised Seasoar Winch

National Oceanographic Centre (NOC) are seeking to procure a dedicated containerised winch system for Seasoar operations. The Seasoar winch that NMF-SS currently have in service was procured in 1990 and has now become prohibitively expensive to maintain and due to its age has a heightened risk of failure. Seasoar is a towed undulating vehicle weighing approximately 350kg in air. The vehicle is towed on Rochester 7-H-314A 8.3mm 7 core conducting cable that is shrouded in an Indal Fathom Flexnose FA-478-350-1 segmented hard-fairing. The fairing is constrained every 2m with a swaged on aluminium ferrule. The wire has a MBL of 5T, but in our experience of destructive testing, usually breaks at 5.6T. NMF-SS use a WLL of 2T with a FOS of 2.5:1. The minimum bend diameter of the bare wire is approximately 0.5m and for the faired wire this is increased to approximately 1m. The Seasoar vehicle is normally towed for between 6 hours and 7 days continuously with a ship speed of 8-9 knots. Seasoar undulates between the surface and approx. 400-500m depth below the surface. The Seasoar dive period is approximately 15 minutes and peak towing loads are usually approximately 1.5T. Vessel speed is reduced and Seasoar brought to the surface for recovery with normal loads of the order of 750kg. It is the view of NMF-SS that successfully scrolling the faired tow-cable without damage will require careful design effort and is the hardest part of the project.