I have 2 thru hulls, they are garmin and apelco
bronze, but really they are Airmar. Meaning drill big hole and attach with angled fairing.
The Garmin is a 6 pin, and the Apelco is a 7 pin. Apelco transducer was already in hull when I bought boat, I added the Garmin later.
I figured out the
wiring pinout and hooked them into Eagle Fisheasy 320c and 340c color fishfinders, so far they have both worked fine together, each on their side of the hull about 15 feet back from the bow.
Detects no problem shallow or deep.
I even have the speed configured and the temp. The speed had an adjustment in the settings, but temp I had to use an adjustable resistor on the mainboard of the unit.
Bought a 6 pin socket for the garmin and mounted it into the Eagle FishEasy, I had the old Apelco, so salvaged its 7 pin
plug and put it into the other FishEasy.
I bought everything used and spent under $150 for all of it.
$25 for a 340C
$60 for Garmin transducer
$40 for 320C
$6 for a 6 pin socket.
I tried the shoot
thru hull thing, but honestly was not great, lots of
noise.