3
Back-up memory:..........Built-in memory stores sonar settings for
decades.
Languages:......................10; menu languages selectable by user.
Sonar
Frequency:......................50/200 kHz for SeaFinder 640c DF; 200
kHz for FishMark 640c.
Transducers:..................A dual-frequency Skimmer
transducer with
built-in temperature sensor is packed with
the SeaFinder 640c DF. It has 35°/12° cone
angles. A single-frequency Skimmer trans-
ducer with built-in temperature sensor is
packed with the FishMark 640c. It has a
20° cone angle. Transducers operate at
speeds up to 70 mph (61 kts)
Watts:............................... SeaFinder 640c DF: 4,000 watts peak-to-
peak/500 watts RMS. FishMark 640c: 1,500
watts peak-to-peak/100 watts RMS.
Sonar sounding
Depth capability:...........SeaFinder 640c DF: 1,500 feet (457 me-
ters). FishMark 640c: 800 feet (244 meters).
Actual capability depends on transducer con-
figuration and installation, bottom composi-
tion and water conditions. All sonar units
typically read deeper in fresh water than in
salt water.
Depth display:................Continuous display .
Audible alarms: .............Deep/shallow/fish/zone.
Automatic ranging:.......Yes, with instant screen updates.
Auto bottom track:........Yes.
Zoom bottom track:......Yes.
Split-screen zoom:.........Yes.
