I've just wired up my Gaffrig depth sounder and have the transducer plugged in but not glued down yet. I thought I would test it before attaching it permenatly. So here is my question: The gauge comes on but I get a reading of 0 feet no matter how high or low I hold it from the ground, then I thought maybe it needs water under it to fuction properly. Does anybody know if this is correct? I just don't want to glue down the transducer if it is not working.

It's my understanding that first it needs to be glued down making sure there are no bubbles in the glue which will affect the ping orecho it shoots and recieves which I also believe that it needs water to recieve the sound wave as it travels thru the water. It's not a radio signal that will work out in the open air. BUT, I could be wrong?

I have heard the same thing as what FBPilot is saying, I hope it's true cause I cleaned the spot my old one was in & glued the new one without testing it. The old one worked ok til the head unit fried so I hope all is well. Good luck, Randy

sound waves travel much better thru water and take much less energy to do so. Your little depth sounder doesnt have the umph or the calibration to pass thru the air.

I have the Gaffrig [ same as the Lowrance 3500 high speed unit] head unit with in hull transducer. The boat needs to be in the water to get the echo signal. I see in your avatar you have an older Fountain. Newer ones are foam cored and that could be an issue. Not sure if your 85's solid or foam cored? In hull transducers work best in solid fiberglass hulls.

It needs to be glued down to work. You should be able to feel the bottom of the tranducer vibrating a little when its on and not glued down though.

Thanks guys for all your responces. It makes sence what you all are saying. I guess I will go ahead and glue it down and hope all is well with it.