If you have the simple digital display and 2 switches (on/off and alarm), then you probably have the standard horizon 41BD. Here's the owners manual -
http://www.standardhorizon.com/downl...pplication/pdf and here are the instructions for changing units:
Units of Measure
To select the displayed unit
1. Turn the power off with the Depth switch
2. Apply power by switching the Depth switch while holding the alarm switch down.
3. When the unit is on, release the alarm switch.
The display will indicate the current display unit with: Feet Meter Fathoms
4. Use the alarm switch up and down to change the value.
5. Five seconds after the last switch press, the units will be saved to memory and the instrument will return to the depth sounder mode.
The display will now indicate the current water depth in the selected display unit.
Want to really scare them - change it to fathoms!
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