Abstract
On bow thruster performance, only the effect of forward speed has been mostly investigated in the past. However, the effect of shallow water will be considered as the very important factor for the performance, because the bow thruster is generally used in shallow water such as harbour, bay or canal. This paper dealt with shallow water and forward speed effects on bow thruster performance, which are investigated by theoretical method developed by one of the authors and also by the experiment used a model ship of 3.0m length. From the results of numerical calculations and the experiment, both lateral force and yawing moment acting on ship induced by the bow thruster decrease abruptly as increasing forward speed in shallow water. For example, the lateral force at forward speed 1.4kt in full scale ship and water depth/draft ratio H/d=1.2 (H: depth, d: draft) will be 30% decreasing than that in H/d=6.0 which is able to consider to be deep water. Furthermore, in the turning motion of ship used only bow thruster at it's forward speed in this shallow water condition (H/d=1.2) the angular velocity decreases about 50% than that in deep water by simulation study. Thus, the shallow water effect is significant factor for bow thruster performance, and therefore this effect should be also considered at the design stage.
