Re: so if i mount a depth finder inside my hull?
The transducer contains a piezo device which bends when excited by electric current or sound.
If you hit it with electric current it generates soundwaves at a frequency determined by how it's cut.....say 200 kHz for mine. Your "ping" , which is also your zero depth reference is transmitted into the water this way.
Time is measured by your electronics from the time the ping is sent out till any replies (pongs) are received and is proportional to the depth shown on the display for that reply.
On the return "pong", sound waves are reflected off whatever they hit down in the water and when they strike the piezo it generates an electrical signal which the electronics registers. Obviously different targets generate different electronic signals and make for different impressions on the display.
The main requirement for low loss is a solid medium (to transmit through); doesn't matter what it is as long as you can transmit sound through it. The more efficient it does that, the lower the losses as compared to a transom mount.
And for folks running under 100 ft. you probably won't know the difference, except it may contain less interference as it is less prone (in my case) to bubbles.
Hence when mounting inside the boat, choice of mounting location, mounting material, and consistency is important. Most mfgrs of sonars tell you what glue to use and how to do a good job.
HTH,
Mark
