Helix 9 Interference from Outboard

[StarcraftSS]

Helix is wired directly to a dedicated battery. The only thing that is wired to the battery is the Helix and an older HB unit on the bow. The bow unit wasn't used today so I have no idea if it's having the same issue.

No interference when the outboard is at idle, but as soon as it's put in gear and I start to raise the rpms...the interference starts (and gets worse a rpms rise).


FYI: I just installed the Helix at the helm yesterday(used to be mounted on the bow)....and redid the wiring also. Ducer is mounted on the transom on the starboard side of the outboard.

I have no idea how the outboard is interfering with the fish finder....seeing that they have no wiring in common. (onboard charger not connected to main battery...or dedicated fish finder battery. Charger only hooked up to troller batteries.

[Wayne P.]

I am going to guess your transducer cable is bundled with the wires from the engine harness to the gauges. The tach gets pulses to calculate RPM's.

[StarcraftSS]

Tach doesn't work. No idea why. Wasn't working when I bought the boat(last year). Although maybe tach signal is still pulsing....and it's the tach itself that's broken.

The transducer cable does run inside the starboard side of the boat(along with all other wires).

[StarcraftSS]

I pulled transducer cable rerouted it. I made sure it wasn't close to the engine wiring harness(both of which run inside the starboard gunnel). Only problem is that the ducer cable and the engine wiring go through the same hole in the splashwell. HB is still getting motor interference as rpms rise.

Is there something that I can wrap the ducer cable with to shield it from the wiring harness (where the wires converge at the splashwell hole) ?

Is it at all possible that prop turbulence(rather than electrical noise) is causing the interference?

BTW:I replaced the tach and it's fully functional, so that confirms that I'm getting rpm signal from the motor.

[Wayne P.]

I pulled transducer cable rerouted it. I made sure it wasn't close to the engine wiring harness(both of which run inside the starboard gunnel). Only problem is that the ducer cable and the engine wiring go through the same hole in the splashwell. HB is still getting motor interference as rpms rise.

Is there something that I can wrap the ducer cable with to shield it from the wiring harness (where the wires converge at the splashwell hole) ?

Is it at all possible that prop turbulence(rather than electrical noise) is causing the interference?

BTW:I replaced the tach and it's fully functional, so that confirms that I'm getting rpm signal from the motor.

Unless you run the outboard in reverse or have the transducer aft of the prop, there is no "prop turbulence" that can affect the transducer.

[Bob B]

You need to determine if the interference is being picked up by the transducer cable or the power cable. You could temporarily run power to a stand alone battery or to a trolling motor battery without the trolling motor running and see if you still have it.

[StarcraftSS]

You need to determine if the interference is being picked up by the transducer cable or the power cable. You could temporarily run power to a stand alone battery or to a trolling motor battery without the trolling motor running and see if you still have it.

Both Humminbirds run to a dedicated battery (bilge pumps are hooked up to this battery also..but obviously the pumps weren't running).

Took this video yesterday. I was drifting and still got interference. The TM wasn't running(but was plugged in) and main motor was off.


When I do run the main motor and rpms get to about 2k...the side imaging goes black

[Bob B]

There has to be something else on or there would be no source for interference......are you sure you aren't getting crosstalk between the 2 units.

The SI may be going black because the SI transducer is getting turbulence and looses signal above a certain speed.

[StarcraftSS]

Doubtful there's any cross talk between HB units. First: they aren't connected together(i.e. ethernet cable)...and second: the bow unit has been "off" most of the time.

[Bob B]

The Ethernet connection has nothing to do with it ..... if they are running the same sonar frequency they can interfere with each other .... of course if the other unit is turned off it isn't going to be the source of interference.

[ezfishn]

Were you near any other boats? Seems strange you would get interference with only the graph turned on.

[StarcraftSS]

Were you near any other boats? Seems strange you would get interference with only the graph turned on.

Nope. Just slow drifting in the river. I was drifting past a marina when I took the video, though. I wonder if anything there could've affected the graph.
Probably should pull the ducer cable...and temporarily route it up and over the splashwell(vs thru the hole) and across the deck to the helm...to see if that helps. If no joy...then the power cable must be the culprit.

[Terryg]

How much distance does the ducer cable need to be away from the bundle of wires? I've got the interference with rpms above idle.

[Bob B]

Right now this makes no sense ..... it can't be motor interference if it does it without the motor running.

[Terryg]

The interference I'm getting is with the motor running and rpms above idle. Sorry for the confusion. I didn't want to start a new thread and wasn't able to find answer by searching.

[StarcraftSS]

Right now this makes no sense ..... it can't be motor interference if it does it without the motor running.

Ya...it had my head spinning also. I haven't had that interference(with everything off)....since.
I am still dealing with the interference with the outboard. I did raise the rpms of the outboard(without it in gear)...and noticed a bit less interference. So I'm now wondering if it's a combination of electrical noise AND prop turbulence.

I have an additional SI ducer mounted at the bow(on a "fishing specialties" pole mount) for a HB 898. The units are not connected by ethernet cable...so I may run that ducer wire from the bow to the helm HB...to see if the interference remains. If it eliminates the interference....then I'll know its the rear transducer cable(and/or it's installation) that's the culprit...and NOT the power supply wire.

[sfw1960]

Tach doesn't work. No idea why. Wasn't working when I bought the boat(last year). Although maybe tach signal is still pulsing....and it's the tach itself that's broken.

The transducer cable does run inside the starboard side of the boat(along with all other wires).

Even if the tach is junk, it is still getting ignition pulses sent to it - unless this is disconnected at the engine - and even then, the engine can be emitting spray - no idea where it can be coming from though, that would have to be inspected for the correct wiring and probably have the tach fixed.

This seems to be coming "thru the air" and could be jumping on the DC or XDCR wiring.

If you can find an old 2700uF or larger (prob. 24v min) electrolytic capacitor - you could put that between the leads on the PC & see if that helps.

Most folks don't suspect the PC because it has a filter - but that doesn't mean it gets everything....

[StarcraftSS]

Even if the tach is junk, it is still getting ignition pulses sent to it - unless this is disconnected at the engine - and even then, the engine can be emitting spray - no idea where it can be coming from though, that would have to be inspected for the correct wiring and probably have the tach fixed.

This seems to be coming "thru the air" and could be jumping on the DC or XDCR wiring.

If you can find an old 2700uF or larger (prob. 24v min) electrolytic capacitor - you could put that between the leads on the PC & see if that helps.

Most folks don't suspect the PC because it has a filter - but that doesn't mean it gets everything....

I replaced the tach a few days ago with a 2 year old Faria I had laying around. Works well.

I think that hooking up the bow ducer to the helm HB...should help me identify the culprit. Wish I had thought of it sooner.

Winds going to be 15-25mph for the next couple days....so going to have to wait to test it out.

[StarcraftSS]

Update:
Disconnected the transom ducer and hooked up the bow transducer to the Helix 9. Ran the outboard up to 7mph...and got no interference.

Now I've got to figure a way to run the transom ducer cable to helm without going through the splashwell hole...so it stays away from the outboard wiring.

[sfw1960]

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