High strength earth magnets and starboard is one of the most convenient ways to mount a transducer. Screw your transducer bracket mount that comes with your unit to the starboard and then sandwich the two halves to your boat.
Ideal for aluminum and thin-walled punts. Note: this mount is not designed for gas motored boats and will come off at speed but at trolling speeds and scouting with electric motors, it is perfect.