From the series 6000-7000 manual:
You can select individual units of measure to create a customized system of measurement for your chartplotter display.
1. From the Home screen, select Configure > Preferences > Units > System Units > Custom. 2. Complete an action:
• Select Depth, and select Feet, Fathoms, or Meters.
• Select temperature, and select Fahrenheit or Celsius.
• Select Distance, and select Miles, Kilometers, Nautical (nm, ft) or Nautical (nm, m).
• Select Speed > Vessel Speed, and select Miles per Hour, Kilometers per Hour, or Knots.
• Select Speed > Wind Speed, and select Miles per Hour, Meters per Sec, or Knots.
• Select elevation, and select Feet or Meters.
• Select Volume, and select Litres, US Gallons, or UK Gallons.
• Select Pressure > Gauge Pressure, and select kPa or psi.
• Select Pressure > Atmo Pressure, and select Millibars or inches of Mercury.