Ship-Induced Bottom Pressure on a Canal With or Without Floating Ice.

Measurements were taken of the pressure induced at the bottom of a canal by a moving ship model under various conditions: on three different straight courses in the canal, over a speed range of 0.5 to 1.7 ft/sec, in clear water and in the presence of a variety of simulated ice floe configurations. The speed parameter is found to be the single predominant factor influencing the pressure signature, whereas the presence of ice floes is of comparatively minor importance. The pressure signal varies with velocity as the square of velocity at the lower end of the speed range to the fourth power of velocity at the higher speeds. This speed effect on the pressure is in fact a manifestation of the influence of sinkage, a characteristic of ship motion in restricted waters which is of paramount importance. An attempt is made to interpret the results of these experiments in the light of a one-dimensional flow analysis in order to suggest explanations for some observation that the pressure signal is greatly reduced by the presence of ice floes.