1. Uncluttered interface

Working on the assumption that, on a boat, many users will wish to use a small laptop, such as a 12-inch iBook, we have tried to preserve as much screen area as possible for the actual chart. The information panel for Routes, Waypoints, Chart Info, Dead Reckoning and so on is kept as small as possible and can be closed when not in use. The primary controls are all accessed from the main toolbar at the top of the screen.

2. Chart thumbnail

Because charts are very large (typically 6000 x 4000 pixels) only a small part is visible on screen at any time and it is easy to become confused as to which part you are currently looking at. For this reason, a thumbnail of the entire chart is displayed in a separate window in the top right corner. The red rectangle in the thumbnail shows which part of the chart is currently displayed in the main window. You can click in the thumbnail or drag the red rectangle to scroll the main chart to a new position. The blue border shows the outline of the panel or plan that is currently showing, which is helpful for charts that have multiple plans. The thumbnail itself can be minimised when not needed.

3. Chart info

Various information about the chart (and any specific plan or panel within it) can be displayed. This includes data such as scale, depth units, datum and projection.

4. Position display

Press 'Shift' to display the lat/lon at the cursor's current position as you move the mouse around. If the cursor is over any point on the track, the time at which you reached that point is also shown.

5. Zoom

The chart should normally be used at 100% magnification; it should not be relied on for actual navigation at any other setting. However zooming to other levels can sometimes be useful (eg, zoom out to 25% to get an idea of which parts of the chart were affected by an update), and so magnifications of 25%, 50% and 200% are provided.

6. Datum switch

Latitude/longitude will normally be displayed on the datum of the chart (which will correspond with the grid shown on the chart). However, you may on occasion wish to display them on WGS84 datum (which should correspond with the GPS unit's display). A toolbar button allows you to switch between the two.

Particularly when using GPS, it is vital to understand the significance of datums. A lat/lon on one datum can be significantly different from one on another datum (hundreds of metres, or even more). Click on 'Chart Info' to see the 'shift' between chart datum and WGS84 for the current chart panel.

7. Change chart palette

ARCS and NZMariner charts are capable of display in three colour schemes. The normal one is for use in daylight. Another with more muted colours is for use around dusk, and another with very dark colours is for use at night. The idea is to reduce the amount of time needed for your eyes to become accustomed to the dark after looking at the screen. PassagePlus allows you to switch between these palettes whenever you wish.

8. Preferences

The preferences allow you to set up the environment to suit you. You can set:

1. ‣Colours and sizes of the various interface elements, such as routes, waypoints and tracks.
   

2. ‣Number of charts retained in the ‘recent charts’ list.
   

3. ‣Lat/lon display format.
   

4. ‣Track smoothing tolerance.
   

5. ‣Location of data files.
   

and a number of others.