| 摘要 |
An electronic navigation apparatus is provided for aiding navigation of a marine vessel comprising: a means for determining the position, speed and direction of the vessel; a means for calculating a predicted arrival time at points in a monitored zone, the zone being selected based on at least the position of the vessel; means for calculating the water depth at points in the monitored zone, by applying tide data to depth data for the respective predicted arrival times; and means for determining whether the expected water depth is sufficient for safe passage of the vessel. A GPS receiver may be used to determine the position, speed and direction of the vessel. An electronic navigation chart may provide depth information. The predicted arrival time may take into account tidal flow rates. If the expected depth is insufficient for safe passage of the vessel, an alert may be generated. Calculated expected depths may be calibrated via measured depths from a depth sounder. In a further embodiment a navigation arrangement is provided for determining whether the marine vessel is expected to be able to pass beneath an overhead obstruction. |
