When moving from one chart area and scale to another, the depth measurement unit may change from among feet, fathoms, meters -- note about Fugawi Aboard seamless chart soundings

Article FA22158, June 25, 2015

Navico and Raymarine plotters display Fugawi Aboard have access to depth measure unit information embedded in any chart area and detail level currently in view.


The Fugawi Aboard product is constructed from a variety of raster sources to create a seamless chart that is familiar to people who have experience with paper-like raster charts. Different source charts use different depth measure units for the soundings according to the intended use and audience of the individual charts. Since Fugawi Aboard stitches together many such charts from diverse survey sources, depth measure units may change from one chart to another. For example, you may be viewing one chart area whose depths are in fathoms but then an adjacent area (perhaps at a different scale) presents depth in meters. There will be many long stretches of adjacent charts that are quite uniform in terms of the depth unit used; but you should be aware of the possibility of transitions of depth unit when moving from one chart to another.

Fugawi Aboard charts viewed in MFDs / plotters include definitive information about which unit measure is used for the depth soundings within a specific chart area and detail level. In all compatible plotters the boundaries used for source charts may be displayed so you can identify where depth units may change:

  • For Navico (Simrad, Lowrance and B&G) plotters, a vector layer with the units displayed is selectable in the top left corners of any given chart currently in view.
  • For Raymarine plotters, querying for objects at the cursor location displays the source chart's name and the sounding units.

As always, care should be taken when planning and navigating across different source charts to verify that the chart's stated water bottom depth along your course is sufficient for your vessel's water displacement plus a reasonable safety factor.

Raymarine touch screen menu

Tap on any point on a chart you wish to know the depth units of. In the pop-up dialog, tap Options. A larger menu appears. Tap Chart Objects.

Raymarine plotter range and bearing pop-up dialog and Options menu

The name of the single chart as given by the maritime authorities appears along with the measurement units used.

Raymarine showing Fugawi Aboard's individual chart name and soundings units