Study on the Optimal Distance Between Two Ships Encountering in a Channel Based on Ship-Ship Interactions and Bank Effects

When a ship moves in the proximity of the bank and other ships, lateral force and yaw moment are induced due to the influence of asymmetrical flow around the ship, which are known as "ship-ship interaction" or "bank effects". For Two ships encountering in a channel, on the one hand, if separation distance is too small, serious "ship-ship interactions" may results in a collision; on the other hand, if separation distance is too large, serious "bank effects" may result in grounding. Therefore, a reasonable choice of the separation distance is important, especially for unmanned high-speed intelligent ships. This paper analyzed ship-ship interactions and the bank effects of two ships encountering in a channel, attempt to find a certain distance so as to minimize the absolute values of resultant force and moment of the two ships in the two-way channel, and built a optimal model to express the optimal meeting distance, which is extremely practical for navigation safety, and can be applied to autonomous decision of intelligent ships. Through a series of tests, the optimal distance between the two ships from the center line of the channel should be roughly equal, and the speed and draft of the ship draft, the depth and slope of the channel relevant to the optimal separation distance.