Here is what you need to do:
1) remove the transducer from inside the hull; place a piece of wood against the hull and tap the wood
with a hammer until the transducer is broken free.
2) Remove any adhesive from the transducer underside with sandpaper; don’t worry if you scratch it. The
plastic is 1/8th of an inch thick and can be roughed up, just don’t gouge it.
3) With the craft in the water in depths over 3 feet deep and the unit turned on, hang the transducer over the side directy in the water with the transducer pointing towards the bottom.
4) If you have readings proceed to step 6
5) If you do not get readings place the transducer up to your ear and listen for ticking from
the transducer. If you don’t hear ticking check the connection to the depth sounder and also verify
that the unit is turned on. Still no ticking, contact NMP customer service.
6) You can then test again or transom mount. http://support.norcrossmarine.com/entries/20692948-how-do-i-glue-the-transducer-in-hull .