Topic: Black line on 2D Sonar

[Whistler]

I have a constant black line at about the 5 ft depth on my 2D sonar. I am using the y cable with an in hull transducer.  I can make the black bar go away by turning down the sensitivity on the 83khz to -5 or -6. However this seems to cause the unit to struggle to keep a lock on bottom in shallow water.  Does anyone have any idea what could be causing this or how I might correct it?

The unit is working great aside from this issue.

[Humminbird_Greg]

Whistler,
Can you post a screen snapshot or two of this please?  Also list the settings you are using for the Beam Select, Sensitivity, 83kHz Sensitivity, SwitchFire and Surface Clutter menus.

I think that what you are seeing is a part of the surface clutter.  Surface clutter will show more strongly at lower sonar frequencies, so in shallow water I would change to the 200kHz Beam Select menu setting or try setting the Surface Clutter menu to a lower numerical setting as this tells the unit to filter out and display less surface clutter.

[Whistler]

Hi Greg.  It will be a while before i can get back out on the water but I will post a screen shot when I do.  Regarding settings, I have the beam select set to 83/200, sensitivity is whatever the default value is, the 83kHz sensitivity is dialed back to -6 or -5 in order to make the black line go away.  Anything higher and the line is there.  Surface clutter is set to 1.  Switch fire is currently set to off but I've tried it both off and on and it has no effect on the issue.

When I increase the surface clutter to a higher number I can easily see the clutter from 0 ft down to however deep.  But this clutter is not the the same as the black line and adjusting the surface clutter setting does not affect the black line.

One other thing, I generally don't see the black line unless I am over deeper water...say 15 feet or more.

[Humminbird_Greg]

When you make the screen snapshots Whistler, make sure and set the RTS Window to show and on the “Wide” setting.  Make a snapshot with the 200/83kHz setting and again with only the 200kHz setting.  It would also help to make a few snapshots with different Surface Clutter menu settings as well (say at 1, 5 and 10) and this can be done using the 200/83kHz Beam Select menu setting.

If possible: try testing your 1198c Si unit on someone else’s boat (and transducer) to make sure that it is not something specific to either your transducer or how it is installed.

[Whistler]

Greg,

Here are the screen shots you asked for.  You may notice in screen shots 3 and 4 there is a small break in the black line where it disappears.  By switching the sonar to 200 kHz only I could get the black line to go away so it appears to be directly related to the 83 kHz frequency.  I could also get the black line to disappear by turning the 83 kHz sensitivity down to -7.  Depending on the water clarity sometimes -6 or -5 is also sufficient to get the line to disappear.

[Humminbird_Greg]

Whistler,
I think that you are just seeing Surface Clutter in the 83kHz sonar is all.

Did you get a chance to try your 1198c Si unit on someone else’s bat to see if you get the same amount of surface clutter?  This would rule out the transducer as causing this for sure.

[Whistler]

I hadn't been able to try on anyone else's boat but I do not recall this issue before I introduced the y cable and shoot through hull transducer. I guess I could just eliminate using the 83 kHz if needed.

On another note, I'm seeing some engine noise from my outboard when my rpms go above about 1000.  Any way to eliminate that?  The unit is wired directly to the starting battery so I think it is probably alternator noise.

[Humminbird_Greg]

Here are some troubleshooting tips I copied from the Humminbird web site:

What should I do if I have electrical interference from my main motor?

Check your unit
Before trying the below suggestions, turn your depth sounder on without using any options or selections to see if the problem may be in the way the depth sounder was set up to operate. Turn all features on Auto and/or set all options to "Restore Defaults" using the Setup Menu tab. If possible, check your depth sounder on a friend’s boat that has the same type of depth sounder and model number. This will indicate whether the problem is with the depth sounder, the installation of any accessories, or with other equipment on your boat. If the depth sounder still has the same problem on your friend’s boat, return it along with a letter explaining the problem in detail. If the depth sounder works correctly on your friend’s boat, proceed with the appropriate suggestions below.

* Check your depth sounder for interference with the boat sitting still, with all electrical equipment and motor(s) off. This will eliminate any possible source of interference. If this corrects the problem, then the depth sounder is receiving electrical interference from your boat equipment.
* To determine the piece of equipment that is interfering with your depth sounder; turn each piece of equipment back on individually, until the problem starts again. When the problem begins again, the last piece of equipment turned on is interfering with the depth sounder. Also try this with your Main Motor and Trolling Motor running at different speeds.

Main Motor Interference
* Route all depth sounder cables as far away as possible from the main motor and any electrical wires attached to the motor. This will help eliminate interference to the depth sounder.
* Using an In-line fuse, connect your depth sounder directly to the battery. This may eliminate faulty electrical connections and electrical interference, which may be causing your problem.
* Have your boat’s grounding system inspected by qualified personnel. Your depth sounder may be trying to operate on a "floating ground.
* Connect your depth sounder to a battery that is not being charged by your main motor. If connecting to a trolling motor battery, make sure you use the battery that provides the 12-volt power on boats that have a 24 or 36 volt system.
* Interference from your main motor can sometimes be eliminated by installing resistor-type spark plugs. Also, worn spark plugs have been known to cause interference with electrical equipment. Most new motors come from the factory with resistor-type spark plugs installed, so have qualified personnel check for the type and wear on your spark plugs before installing a new set.
* Unplug the tachometer, preferably at the motor. This will help eliminate interference being coupled into your depth sounder by the main motor through the tachometer.
* An electrically noisy battery charging system on your boat’s motor can also cause interference. Have this specifically checked for by qualified personnel.


If you are still having this problem than try contacting the Humminbird Customer Resource folks at 1-800-633-1468.