Fig.5. |
Ship model C2: lateral force and yawing moment due to ship-bank interaction in absence of propeller action as a function of ship-bank distance for several water depth to draft ratios. |
4.5 Propeller action.
Propeller action ahead appears to result into an attraction between the stern and the bank. This effect is illustrated in figure 6, showing the results of model tests carried out at zero forward speed.
In combination with forward speed, the bow-away yawing moment, which already occurs at zero propeller rate, is amplified by propeller action. At very low h/T, bank repulsion at zero rpm can be changed into bank attraction due to this effect; if the depth to draft ratio exceeds the critical value, the lateral bank attraction force is increased due to this propeller effect (see figure 7).
Fig.6. |
Ship model C2: lateral force and yawing moment due to ship-bank interaction induced by propeller action at zero forward speed as a function of ship-bank distance for several water depth to draft ratios and propeller rates. |
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