| 摘要 |
Means for determining whether a marine vessel of known height above a water surface is able to pass beneath an overhead obstruction, such as a bridge, by: determining the marine vessels position, direction and speed; calculating a predicted arrival time of the vessel at the overhead obstruction; calculating an expected water depth at the location of the overhead obstruction at the predicted arrival time; calculating the expected clearance distance between the water surface and an obstruction minimum altitude based on the expected water depth at the location of the overhead obstruction at the predicted arrival time; and comparing the calculated expected clearance with the maximum height of the marine vessel above the surface of the water, to determine whether the calculated expected clearance is greater than the maximum height. In another embodiment, a navigation arrangement is provided for determining when an expected water depth at a point in front of a marine vessel is insufficient for safe passage of the marine vessel, and a required speed for the marine vessel at which the expected water depth at a predicted arrival time at the point will be sufficient for safe passage of the marine vessel. |
