Re: transducer----transom mounted or thru the hull
My GPS came with a transom mount transponder. I'm not sure if I want to use that or buy a thru hull transponder. Is the performance that much better to warrant the $200 part?
Another concern is that at some point I am going to put trim tabs on the back of my boat. The transponder might be in the way?
While the shoot thru eliminates a lot of the mounting problems typically associated with a transom mount, you could give up a good bit of sensitivity when shooting thru the hull.
I fish so a units sensitivty is of primary importance to me. If you don't fish then it may not so much.
Transmission losses through the hull are due to two factors:
1. Absorption of the ultrasonic energy by the fiberglass hull. The thicker the hull, the greater the absorption.
2. ?Impedance mismatch?: the thickness of the hull in wavelengths at the operating frequencies can cause
transmission loss and shift the transducer frequency
? For hull thicknesses of 1/4, 3/4, 5/4, etc?, hull losses due to impedance mismatch will be lowest
? For hull thicknesses of 1/2, 1 and 1.5 wavelengths, losses will be highest.
In-Hull Transducers and Fiberglass Hull Thickness
@ 50kHZ
0 = 0
3/8" = 5% loss
?" = 10% loss
?" = 3% loss
1? = 7% loss
@ 200kHZ
0 = 0
3/8" = 7% loss
?" = 3% loss
?" = 5% loss
1? = 4% loss
