| 摘要 |
PURPOSE:To prevent false display of a wake being identical in the time and different in a date and to display only a desired wake without fail by setting a range of display on the basis of data on the date and time on the occasion when the content stored in a wake memory is displayed. CONSTITUTION:A position measuring means 1 measures the present position of its own ship and makes a wake memory 2 store it together with the date and time of the measurement, while a wake display control means 5 prepares data for wake display on the basis of the content of the memory 2, writing them in a display memory 3 and also making a display unit 4 display them. A reading means 7 of the data on the date and time reads the data on the date and time in a range to be erased according to specification of an operator, and a wake erasing means 8 retrieves position data stored in the memory 2 together with the data on the date and time in the range to be erased and erases the corresponding position data. According to this constitution, it is prevented that another wake being identical in the time and different in the date is erased falsely, and only an unnecessary wake can be erased without fail. |
