A friend told me today that turning on your fishfinder and letting the transducer click while out of water can damage it.  I do it occassionally before a trip to make sure it's working and to make adjustments.  I think he's full of crap.  Who's right?

I don't turn my bow finder off when I pull the TM out of the water to move to the next spot and I've never had a problem in all these years.

Myth busted.

I don't see how it could be damaging.  It doesn't know if it's in water or not.  

A time or 2 I have had a brain fart and left my unit on in the garage 'till it ran the battery down. It never hurt the transducer 1 bit. I'd say your friend has "stinky breath".

I read this same thing somewhere about leaving it on was harmful to the machine, but like Cart said, I have left mine on before and no damage. I also read that some of the more powerful units can cause severe pain to your hand by putting it under the transducer while under water. I don't know about that one either?

I don't see how it could be damaging. It doesn't know if it's in water or not.

Absolutely correct. No, it can't hurt you.

I have heard the same BS about the transducer being out of the water so I asked a sonar guy at work today he said it wouldn't hurt it at all.

Full of crap he is  ;D

No and No.