Transducer help

[Reel Overtime]

I have a lowrance hds-8 and last year changed the ducer to a airmar p 66,  the screen is clearer while trolling in the 50 hz, but when i troll at a faster speed or throtle up to go we have alot of interferance, I was thinking of going to an airmar b 164 thru hull,  (lowrance recomended)    any thoughts or suggestions.???..I troll with the main motor and bags...

Ready for something, new ducer, new fishfinder, something,, just not happy with this set up....

Thanks Rick

 

[Sk8man]

A few things come to mind. The first is the actual placement of the transducer on the hull of the boat and the angle of the face of it, Airmar transducers are some of the best out there but they are also sensitive to the flow of turbulence as are most other transom mounted transducers.  This flow may change significantly with the rise or fall of the boat hull when accelerating.  Any strakes or chines on the hull that are near the transducer face can create havoc as well.  You may wish to experiment with transducer placement before doing anything drastic by mounting it to a metal plate possibly bent if necessary to mimic the correct position of the face on the hull with suction cups on it and move it around and test out various positions for optimal placement (secure it with a safety line too). The second thing is electrical interference coming from your engine at certain speeds for which you may think about installing resistor spark plugs and see if this helps. This may even be the first thing to try. Another thing to try is reducing your sensitivity setting on the finder itself to different levels and try them out to see if it makes a difference. A lot of times with the higher settings or even auto sensitivity setting will generate a lot of interference or "clutter" on the screen when underway at increased speed.

[TyeeTanic]

Other issues that can cause this, but you probably already know:

 

- are you powering the head unit directly from your 12V battery? Is it a clean connection (not taking off power to any other users from this, or not off a distribution bus or switch panel)? Any bad ground will cause interference, unless you have a clean, dedicated cable from the battery to the head unit.

 

- how have you run your power supply cable? Is it run close to the power cable to the engine? At certain engine frequencies, power to or from the engine can interfere with other power cables.

 

- have you used the right power cable? 14 gauge (16 min, but you need to check distances).  Correctly insulated cable, marine grade?  Too small of a wire will heat up due to resistance, especially over long runs. Also poor quality cable is not shielded as well, so it can increase level of interference from other power consumers or sources.

 

- what kind of interference are you talking about?  Lots of color at the top of the screen (prop wash) or dots and dashes everywhere (electrical interference).  You could try and reduce your sensitivity, but that will also reduce the fish you see.

[Reel Overtime]

After reading this tyee tanic, I think i need to check the electrical, I had it re wired from the local marina while it was there, not sure if it is right...

[mudflat]

Should be able to get that P66 dialed in once you figure out what's causing the interference

Does the interference change with motor rpm's (electrical) or does it seem to be just correlated with your speed (transducer placement). Try "revving up" your motor a little in neutral and see if it affects your screen. Does it get worse while you're using any other electrical device (riggers, radio, ect).

If you do decide to go with a thru hull look at an Airmar B60, it has a wider cone angle than the B164 and might be better suited to our kind of trolling.

[Reel Overtime]

There is a fuse block wired direct to battery, this has My fish finder, garmen gps, marine radio and fish hawk wired to it... the down riggers are wired direct to battery at the same location...   this was installed by the marina when they did the auto pilot... should I seperate...???

Thanks Rick

[lineman49]

Did you go into the installation/set up page & tell the unit which X-ducer you have? Also as Les said the auto sensitivity may be too hi, I had to set mine on a -5 to clear the clutter & get a good pic. & be sure to use a safety line if you move it around.

[jimski2]

200 kHz is recommended for high speed use. 50 and near frequency units for slow trolling speeds.

Sent from my iPhone using Lake Ontario United mobile app

[TyeeTanic]

That fuse block uses a common ground, so you can pick up interference from any one of those devices. So to be safe I would go straight to the battery, with an inline fuse on the live wire (as close to the battery as possible).

 

Also 50 Hz does get interference from the engine at certain RPMs. I heard it was +800 rpm, not sure.  Going to 200 Hz will show less noise. 

 

Finally, if you do have prop wash/turbulence on that transducer as Sk8man says you won't be able to do anything about it.

[Reel Overtime]

Thanks for the replys so far,  I just did the up date from the lowrance web site, changed the ducer setting to a p-66 and also changed to a slow troll setting, unit was clear in marina, clear while idleing out, clear if i reved engine up, but screen changed colores as we picked up speed, I never lost bottom running at 30 mph but you will never see fish...I am headed up this weekend and will re wire direct to battery and adjust sensitivity lower for 200 hz, It did seem to be about the 900 to 1100 rpm that the screen got funny so next will be a transducer move away from outdrive,  I can only move over about 4" and than it will hit a trim tab, not sure how close to this i can go...

Thanks for all your help    Rick

[jimski2]

Usually the higher speed fish will appear as blips on the flasher component of your screen.

Sent from my iPhone using Lake Ontario United mobile app

[Sk8man]

You need to stay away from any hull features that might create turbulence so your choices may be somewhat limited by that sometimes it amounts to the "lesser of evils" and trying to get the best possible placemment out of the available choices.

[Rippin'Line]

If you you do run the unit off a bus bar for ground but use the secondary ground cable directly to the battery it should clean up alot. Now i have a Garmin so I dont know how the Lowrance units work but I know that mine has that option. All of my electronics on the dash go to a fuse box then to the battery.