Topic: Erratic Depth Readings

[fishawk]

hi Guys,maybe somebody can help with the issue i am having.I am running two Transducers a 83/200 and a 50/200 thru hull,do lots of shrimping here in Alaska,and need deep depth readings for setting pots.and I am getting erratic depth readings while sitting still or moving, setting shrimp pots with the 50/200 transducer set on 50,I am usually setting pots in the range of 520 to 800 ft.But it seems to work fine in water to about 380 ft.With either transducer, does not make a difference,I have set the unit to deep saltwater,auto range, and have tried manual range,adjusted sensitivity,set to max mode,clear mode, reset unit,Cleaned transducers,also turned off and back on again and seems to work fine at first then gets improper readings.It usually says its 16 to 40ft in 700ft of water.I am thinking there is something wrong this unit, or is it my transducer installation?But the thru hull should be working for that kind of depth.Thanks

[Humminbird_Greg]

fishawk,
By “thru hull” are you meaning a true Thru-Hull transducer that mounts under the hull of the boat via a ‘stem’ that goes through a hole in the hull or are you meaning a transducer mounted inside-the-hull of your boat?

This is only happening when in 520 to 800 feet of water when using the 50kHz sonar, correct?

Is there a thick thermocline layer at those water depths?

Make sure all other sonar units are shut off.

See if this happens when everything else on the boat is shut off.

Do you know someone else with a Humminbird unit that would allow you to test your unit on their boat?

Did not realize that pots were used for shrimping, all I ever saw (Gulf of Mexico) were nets.

[ITGEEK]

fishawk:
If interference is not causing this problem, maybe you have a power problem.

I would fully charge and load test your battery.
Also, check that the unit power connections and fuse are tight and corrosion free.

Good Luck.

[fishawk]

thanks for the replies,Greg yes this a true thru hull,Hole in boat hull, and we are now limited to 5 shrimp pots, we used to use 8 couple years ago.Nice big spot shrimp.The unit  is not always intermittent,it will hold depth sometimes for a minute,or sometimes 5minutes,but stay erratic for long and short periods.I run 3 batteries in boat,all brand new this year,all connections clean,tight,corrosion free,and charged.Yes i have been using 50KHZ for deep water,and yes this only happens in deep water 350-400 out to deeper, also tried 200/83 does the same.no thermocline line,water here is  to 37 degrees.I am thinking interference with something,or unit,but works fine until deeper water.thanxs