NEW INSIGHTS INTO VOITH SCHNEIDER TRACTOR TUG CAPABILITY

The emerging use of tanker escort in restricted waters requires tugs t hat are capable of rendering effective retarding and steering assistan ce to large ships operating in the 6 to 12 knot speed range. This pape r presents findings from a coordinated program of model tests, compute r simulations and full scale trials which have yielded new insights in to the capabilities of Voith Schneider propelled tractor tugs. The eme rgency assist capabilities are shown as speed-dependent contours of th e vector assist force in the coordinates of the assisted vessel. For t ractor tugs the capabilities increase with speed. Simulations of tug a ssisted tanker maneuvers at 1 0 knots show that the tractor tug is mor e effective than a conventional tug in controlling the behavior of a d isabled tanker.