Garmin 740 Depth Sounder function

[Fogg~Dogg]

I have a Garmin-740 (love it!) with a transom-mounted transducer...mounted to the left of the rotating propellor - thus no turbulance. At the dock and under-way, the Depth function works fine. But, at about 40 feet deep...the Depth indicator starts flashing, and then it intermittently works. I've checked all my 740 settings, and I've twice this season had the transducer cleaned of scum, weeds, grass...or anything else that might be there. Of course, I'm thinking do a thru-hull transducer next season and all will be well, but I have to believe that the existing set-up should work also. Is there anything else I can try? (FYI, the unit does the same on both shallow and deep water settings on the Garmin.

[OldDemps]

I have a 740 and installed a new thru hull transducer from transom mount according to prior to this post viewtopic.php?f=27&t=2305
I still lose the depth reading but mostly shallow when I need it most. I think like your issue it's bubbles under the transducer interfering with my signal. I tried every 740 setting including lowering power and (dual) frequency to transducer with no success. Overall I'm pleased with the configuartion but the water here in California is deep and less of and issues than east coast boating.
Question, If you're not moving in deep water (>40') can you get a solid depth reading?

[RobS]

Try the gain in manual and crank it up. Won't solve the issue but may improve the signal somewhat..