I can't believe the change of unit is not possible!!
This can probaly help friends able to enter in the Unit software
On Offical HB Faqs is clear the unit works in native METERS.....
The following NMEA Sentences are output from all Fishing System units:
DPT – Depth
MTW – Water Temperature
GLL(*) – Geographic Position (latitude/longitude)
GGA(*) – GPS Fix Data
RMC(*) – GNSS Data
VTG(*) – Course Over Ground and Ground Speed
ZDA(*) – Time and Date
(*) – These sentences are related to GPS and do not contain any information unless a GPS receiver is connected to the Fishing System unit.
If a GPS receiver is connected to the Fishing System unit, then other NMEA sentences containing navigation and waypoint information will also be output by the Fishing System. For more information on the NMEA0183 specification, consult the www.nmea.org
Digital Depth is embedded in the DPT sentence. Its format is as follows:
• d.d is the decimal depth value in meters relative to the transducer
• o.o is an offset from the the transducer to the surface.
• This Depth Offset can be programmed into the Fishing System unit under the advanced main menu system (see Fishing System User’s Manual for more details)
• hh is an automatically generated checksum for communications error checking
• - stands for “carriage return” and “line feed” which indicates the end of the transmitted sentence.