[1] Rolls Royce Marine AS, NO-0161 Oslo, Norway
[2] Norwegian Univ Sci & Technol, Ctr Ships & Ocean Struct, NO-7491 Trondheim, Norway
[3] Rensselaer Polytech Inst, Dept Elect Comp & Syst Engn, Troy, NY 12180 USA
[4] Norwegian Univ Sci & Technol, Dept Engn Cybernet, NO-7491 Trondheim, Norway