The second of two new Damen ATD 2909 tugs belonging to Serco Marine Services and intended for use on the Clyde was seen arriving early on 12 July. SD DEPENDABLE, whose sister SD RESOURCEFUL arrived a few weeks previously, is the last of four tugs of the type delivered from the Dutch shipyard as part of the 29-vessel contract signed in December 2007 (the other two tugs are SD RELIABLE and SD BOUNTIFUL, delivered to Navy Dockyards at Portsmouth and Devonport). Their hulls were built in Poland although final completion was carried out in Holland. With an overall length of 29.1 metres, they are powered by Caterpillar engines driving twin Rolls-Royce azimuthing units, mounted side-by-side to give a bollard pull of 42 tonnes. Fendering is achieved using a special light grey rubber material to avoid marking the hulls of warships, while additional fendering is fitted below the waterline to allow the tugs to work with submarines.