Transsducer losing bottom

[Major Mark]

I sold my walleye rig & built a 1648 jon boat for river fishing. A buddy gave me his never used Lowrance 520C (nice guy, huh? !!). Problem is it won't hold bottom depth readings. Anytime I get over 3mph or in shallow water the depth starts to flash & takes forever to recover reading correctly if at all (many times a restart is needed & then that doesn't always work). I have moved the transducer up, down, changed angle etc repeatedly. I considering making a leap to a Humminbird 898cSI out of frustration. Looking for advice or opinions if there are any issues with HBs holding bottom? Obviously it will have to be transom mounted, but does side of transom make a difference? At $1500 for the unit plus larger Ram Mount it is a large investment IF it won't hold bottom either. Being in a shallow river by my place in central Wisconsin (Wisconsin River south of Castle Rock Lake)), it is really important to know when the bottom is approaching fast. Any and all advice would be appreciated. Thanks!

 

[Scott Hammer TOXIC]

Where is it mounted now?

 

[Wayne P.]

Transducer placement on a transom for above idle speed depth readings is critical. It has to have smooth, non-aerated water, flowing across it all the time to work properly.



Hull ribs, rivets, welds, dents, etc. will make the placement more difficult.

The brand and unit type makes no difference, although the torpedo shaped Lowrance transducer is more hydrodynamic.

If you can't get satisfactory performance with the unit/transducer you have, you have no chance of getting a Side Imaging transducer to give you high speed depth readings.

 

[Major Mark]

current transducer is mounted on starboard side of transom, splitting the difference between the bottom ribs of the hull, no rivets or anything else in path of water flow. The hull is a flat bottom/bow jon, not a mod V. I was reading the installation instructions of a HB & see they say to mount on the port side if the prop is a clockwise twist but can't where that is a factor in my application. The excess transducer cable is coiled & bound together about 2 feet from the head unit...kind of stumped