GP1971F+B45 BDS not working properly

[jbelsan]

On my GP1971F,the BDS function is showing sand or mud at 99,99% of time no matter what the bottom quality is.
The Airmar B45 is chosen as the active transducer in the menu,I am positive that the tansducer is level when the boat moves and leans 2° front when stopped (We see small jigs till the bottom) no air bubbles or interference noise is present on the screen.
The firmware is the 5.1,Voltage is 28v whith the engine running.The depth we checked the BDS was 12 to 70 meters,the bottom image without the BDS seems OK,showing clear enough fluctuations of the bottom hardness.
I would be gratefull for any suggestion.

 

[Johnny Electron]

I would ensure that you are not running BD and Accu-fish advanced features both at the same time. It is one or the other, not both. Recommend checking that the correct transducer model has been selected for using the B45 (525T-BSD) and that the transducer face is clean and mounted straight.

 

[jbelsan]

Thank you Johnny,I'm gratefull.
Speed was under 10 knots,max depth was 230 ft,B45 is selected but I will check it again.
The boat was out for maintenance and is about 1,5 months in the water so I believe that it should be clean but I will dive and see just to be sure..
We mounted the transducer very carefully to be straight at 5,2 knots which is the idle speed of the engine and when we stop it leans 2° front.Left and right is level.
I think that mounting is OK because when jigging,with the fishing lines vertical (no current at all) we could see 30-40 gr metall jigs all the way down to 200 ft...still the same issue,false BDS regardless of speed.
I will check also that the Accu-fish is disabled.
I consider that Factory settings would not help and I don't think that my 1971f is faulty although one of these days I will check just to be sure with the 1971f of a friend and I inform the forum.
Thank you so much for the effort to help,I understand that there is not much to talk about this problem..even we who mounted the transducer can never be 100% positive...personally I never am.

 

[jbelsan]

Desperate moves I guess but everything works now and I am really happy with the total performance of GP-1971F.
First of all I checked your suggestions to be true in the menu.
Then I changed the draft to be accurate...not sure how these algorithms work,so I maybe got a little paranoid on this.....more than a little I think.
The other thing I tried,was changing the Transducer from 525T-BSD(B45) to 520-5MSD and back again but I don't think that these two moves gave the solution.
I do not know if it will help anybody facing the same issue in the future but I have a general switch on my boat and cut off the batteries from the electrical circuit whenever I leave..
I also don't know if this was the reason for some kind of reset after a week out of the electrical circuit...my Simrad CR-40 suggests that when software problems occure such as freezing etc,to unplug the power cable for some minutes...I know that it worked in several problems I had with the earlier very unstable firmwares.
Thank you for your help,safe seas to everyone.