Garmin NMEA 2000 Backbone/Drop Cable (1 Ft.) [010-11076-03] MRP or float tube in sand

or float tube in sand

and use narrowband sonar transducers

which is easy to install

You can use Vulcan as a simple chartplotter as soon as you connect it to power

Full-Featured Vector Charts

Garmin NMEA 2000 Backbone/Drop Cable (1 Ft.) [010-11076-03] MRP or float tube in sandNMEA 2000 Backbone Drop Cable Extend your NMEA 2000 backbone with Garmin's 1' (0. 3M) backbone drop cable. Compatible Devices: AIS 300 600 Blackbox Transceiver GBT 10 GCL 20 Low light Imaging Camera GDL 40 GET 10 GFL 10 GFS 10 GHP 12 Autopilot System GHP 20 Marine Autopilot System for Steer by Wire, Viking and Yamaha Helm Master GHP 20 Marine Autopilot System with SmartPump GMI 10 20 Marine Instrument GPS 19x NMEA 2000 GPSMAP Series VHF 200 300 Marine