To use a fish finder transducer you should begin by taking your boat into water that is at least 2 feet in depth. Also, always make sure that the water depth is less than the depth capability of the fish finder. You can use depth finders for this.
Remember the transducer should be fully submerged because the sonar signals cannot pass through the air. If the unit is working properly, gradually increase the boat speed to test high-speed performance.