Nautical chart display device, nautical chart display method, and nautical chart display program

A method of displaying a nautical chart, comprising the steps of:

• displaying, on a display so as to be superimposed on a nautical chart, a directional symbol in which directional markers arranged in a circle and the center of the circle are indicated, the directional symbol including a distance scale line extending from the center of the circle, a numerical value indicating a distance being illustrated on the distance scale line;
• detecting an operation to the directional symbol on a screen of the display, and moving the directional symbol according to the operation;
• increasing or decreasing in size the directional symbol according to the operation to the directional symbol;
• and
• changing the numerical value of the distance scale line indicating the distance according to a scale of the nautical chart or the increasing or the decreasing in size of the directional symbol.

A non-transitory computer-readable recording medium storing a control program causing a processor of a nautical chart display device to execute processing, the processor configured to control operation of the device, the processing comprising:

• displaying, on a display so as to be superimposed on a nautical chart, a directional symbol in which directional markers arranged in a circle and the center of the circle are indicated, the directional symbol including a distance scale line extending from the center of the circle, a numerical value indicating a distance being illustrated on the distance scale line;
• detecting an operation to the directional symbol on a screen of the display, and moving the directional symbol according to the operation;
• increasing or decreasing in size the directional symbol according to the operation to the directional symbol;
• and
• changing the numerical value of the distance scale line indicating the distance according to a scale of the nautical chart or the increasing or the decreasing in size of the directional symbol.