transducer

1976 silverton twin eng. heres the ? i am putting another transducer on too go with the garmin i bought. the transducer thats on their now is on starboard side just below the water line and even with the bottom works fine. we run in a lot of low water some times 26 30 inchs.i have measured the distance from transducer to bottom of props. i wondering about putting this transducer in the middle of the stern all the way to being even with the bottom just fig it might be easy. than trying to do the math all the time.also what about prop cavatation?thanks dont mind the spelling

The transducer cone is roughly only 20 degrees from vertical. That's only 10 degrees to a side....not much. In the short distance from the ducer to the prop elevation, and with the prop being on the rear of the engine, the cone is probably so narrow at that point it won't matter.

Why not just mount the ducer in the boat just off the keel and about an inch in front of the transom. You need solid material to shoot through, no foam inner lining like some boats have...glass then a 3/4" of balsa, then more glass. You want solid glass all the way or alum. You are transmitting sound, not electric currents so you want something hard that sound will easily transmit through.

Get a 1 gallon zip lock bag and your transducer. Find a nice quiet cove. Put your ducer where you think you want it and record what you get on the display. With the ducer in the bag submerged in water, put the ducer where I said in the boat. Note the differences. If not detectable, mount it inboard with a good hard epoxy minimizing bubbles when you mix the epoxy. I have done it successfully in all my boats after I got tired of knocking the things off when mounted outboard.

Ducers usually run on 50 or 200 kilo Hertz. If both are the same frequency, expect interference between them if operated simultaneously and the radiation cones overlap....gets worse with increased depth.

When one shoots out a signal and it is reflected back it has no way of knowing which transmiter sent it and both receivers will pick up the same signal. Hence they will talk to each other and it will look like noise/dots/fish that aren't really there on the display, or wavey lines. Solution is to run one at a time or have one at 50 and the other at 200. The front ends are tuned to the respective frequencies and the other frequency is outside the receiver bandwidth and can't get in.

HTH,
Mark