Re: Use Electronics While on Battery Charger?
I am guessing that the modern day transducer can survive well enough being operated with the boat out of the water, and that renaming your boat will not bring bad luck. Here's something I found that may shed some light on the subject.
"E Fitzgerald
05-10-2004, 04:52 PM
The Skipper is right on - heat can certainly be an issue if you operate a transducer that is designed to be in water in air. Transducers are approximately 60 percent efficient in their ability to convert electrical energy (the AC "pulse") into mechanical energy (ultrasound). The electrical energy not converted to mechanical energy is converted into heat. Most transducers use adhesives to hold components together and adhesives can soften when warmed and de-bond the components. Sometimes the effect is temporary, other times it is not. A rule of thumb for operating a marine transducer in air is one minute. Also note that the "range" measured in air will be about 4x greater than the actual distance - this is because the speed of sound in air is approximately 4x slower than than the speed of sound in water.
A secondary issue is that when the transducer is in air, it is not hydrostatically "loaded" that way it is when underwater. If one were to measure the impedance it would probably be different (but I admit that I do not know if the difference is 5 percent or 50 percent or somewhere in the middle.) At any rate, an echosounder might not be tolerant of driving the different impedance. Note that transducers mounted as "in-hulls" (M260s, P79s and the like) are loaded by the liquid in the tank or by the epoxy that bonds them to the hull.
E. Fitz"
http://www.thehulltruth.com/archive/t-22200.html
In the FAQ section , Airmar used to advise, "To prevent damage to the T/D , avoid energizing it for more than 30 seconds out of water."
I have searched the Airmar FAQ's, and I can't find that warning.
