I am old school about mounting these... no wet mounts, no special gimmicks.... just plain marine goop! Very careful to mount level with bottom of yak and with very little goop and bubbles between ducer and hull. Carefully squeeze them out, the goop that leaks out and up the sides of the transducer a bit does most of the adhesion. I have been busy and have not mounted mine yet, but I will mount it behind the mast. I have had good luck with this method in the past. I know some will say I am doing it wrong... but so far it does the trick for me.
After spending the $ on this I will probably not be removing it any time soon.