If you want to rig up your existing FF Check out these guys
http://www.fishfindermounts.com/. They have magnetic transducer mounts and other types of mounting gear for fish finders on smaller boats including small 12 volts.
I have an old portable Humminbird that uses a suction cup to mount the transducer on the boat. Worked pretty well when I was in RI fishing out of a jon boat and using a TM. AH the good old simple days.
http://www.cabelas.com/product/Hummi...3298622&rid=20
