FCV 588 Trolling interference help

[Mgfishing]

Hi guys I’m running a 588 with a TM185HW which usual has great results. Recently I’ve started trolling offshore a lot more & have found that at trolling speed between 7-9knots I’m getting either a lot of interference or water disruption just unsure of which one it is.

I can only run the gain at very minimal 2-3max before it is too much on the screen.
I don’t loose bottom at all, the cable runs port side of the boat opposite to all electrical cabling & is in it’s own split conduit.

When the cable exits the transom it goes across from port to straboard in a mechanically protected aluminium cover then only a few hundred mm of cable is exposed before it’s mounted.

Here are some photos of normal running while bay fishing or sounding for snapper & then offshore at 7-9knots.

Any advice would be helpful

 

[Johnny Electron]

@Deep Blue

 

[Deep Blue]

Mgfishing,

It appears that it might be some electrical interference. Have you connected an earth ground to the back of the unit's grounding screw..? One test that you can try is running the FCV588 to an isolated power supply like a battery and see how the unit reacts.

- Deep Blue

 

[Mgfishing]

I did have an earth connected from the back of the unit to a earth lug behind the dash, but it never really changed the result.

I’m currently running 2 battery’s that goto a battery 1/ battery 2 / battery 1+2 isolator which then feeds an on off isolator on the dash that feeds all my electronics, are you suggesting running a power cable directly off one of the battery’s or a complete new battery?

 

[Deep Blue]

Mgfishing,

Try running the FCV588 on a separate battery with nothing else connected to it and see if you get any interference. And if you can run the unit in MANUAL Mode in deeper water using both the HF and LF and provide us pictures..?

- Deep Blue

 

[Mgfishing]

Mgfishing,

Try running the FCV588 on a separate battery with nothing else connected to it and see if you get any interference. And if you can run the unit in MANUAL Mode in deeper water using both the HF and LF and provide us pictures..?

- Deep Blue

Will do on the next outing. Hard to get a 3rd battery in the boat as it’s already got the 2 optima blue battery’s which are quite heavy and it’s only a 5.2m tinny.

What do u class as deeper water I very rarely fish deeper than 100m?

Just for my own understanding what are your thoughts about trying manual with HF and LF when it’s a HF transducer ? Is it a common issue with them or something?

I appreciate all the feedback

 

[Deep Blue]

Mgfishing,

If you can, please try to provide an Apples to Apples comparison of the FCV588 by doing the following:

• Pick a depth of 10 meters (or more) using the same settings and using the same background of either Blue, White, or Black.
• Say that you are conducting this test in 10 meters of water, then set the FCV588's range at 50 meters.
• Take a series of pictures of the unit while you are drifting, then at 5 knots, then at 10 knots, etc, etc, until you are at full speed.

I am interest to see how the noise on the screen reacts or if there are "patterns" of that noise.

- Deep Blue

 

[Mgfishing]

Will do, won’t be for a couple of weeks but I’ll definitely document all the stuff you have requested

 

[Mgfishing]

@Deep Blue here are the pics you requested, the images are set to manual range 40m depth and the last few are with manual range 20m depth. Each pic has the rpm/speed in a different pic with it, flat conditions and the motor trimmed pretty much right down.

Also this is in the bay not offshore not sure if that is necessary info.

The first few pics are at 40m range and the second lot are at 20m range I was sounding for fish as I was doing the tests hahahaha

 

[Mgfishing]

Next couple are still 40m range

 

[Deep Blue]

Mgfishing,

Thanks for providing these pictures.

I still think that the interference you are experiencing is either from electrical or mechanical noise. I would try this same test again, but using an isolated power supply (like a battery) that directly connected to the FCV588 and see if any of this interference is still present..?

- Deep Blue.

 

[Mgfishing]

@Deep Blue I’ll give this a go next time I’m out, just need to source a 3rd battery to give it a go. It seems to be less when the engine isn’t under as much load. For instance in a following sea when the motor is under less load for the same amount of speed & RPM the noise is significantly less..

Would that tell you what it may be ?

 

[Deep Blue]

Mgfishing,

I agree. It may be caused by the engine's electrical system, or it may be caused by some mechanical harmonics that is creating this interference. This is why I would like to see the Fish finder completely isolated from anything electrical on the vessel.

You don't need to go far from the marina or the boat ramp when you conduct this testing. Just a recording of slow, medium, and high speed of the boat, while the Fish finder is running on isolated power supply should work.

Right now, we are checking off the boxes on what it might be. BTW, what is the manufacture and type of engine that is powering your vessel..?

- Deep Blue

 

[Mgfishing]

Mgfishing,

I agree. It may be caused by the engine's electrical system, or it may be caused by some mechanical harmonics that is creating this interference. This is why I would like to see the Fish finder completely isolated from anything electrical on the vessel.

You don't need to go far from the marina or the boat ramp when you conduct this testing. Just a recording of slow, medium, and high speed of the boat, while the Fish finder is running on isolated power supply should work.

Right now, we are checking off the boxes on what it might be. BTW, what is the manufacture and type of engine that is powering your vessel..?

- Deep Blue

Sorry for the delayed response haven’t managed to get out yet.

The boat is a Makocraft 5.3m
& is running a Suzuki 2018 DF115A

Also because im running a chirp transducer the LF selection doesn’t really work as the transducers operating frequencies don’t got within the tolerances LF need to operate.

I’m headed out Friday, I won’t be able to run a 3rd battery, but I have directly ran the wiring to power the unit to my second battery terminals rather then a fuse box & busbar behind the dash.

Could this help or does it really need to be another battery?

Regardss
Matty G

 

[Deep Blue]

Mgfishing,

Anything you can do will help with the testing. What we are trying to do is locate and isolate any potential source of electrical noise that might be present.

Another thing that you can also do is switch the FCV588's TX Power from 1kW over to 600 watts of power. If there is electrical noise still present, it will still be there regardless what the unit's output power that is being used. This another good way to test for electrical interference.

- Deep Blue

 

[Mehmet Okur]

This is just a suggestion, I recommend that you touch the grounding point on the back of the device to the water with a cable.

 

[Mgfishing]

@Deep Blue Gday mate sorry to bring up n old thread still trying to nut this out.

Definitely an issue when the motor is own, I was put on the weekend & when I was drifting motor off the screen was crisp, soon as I started the motor the interference began.

I’ve got a battery selector/ isolator where I can choose bat 1 - bat 2 - both or off.
The negative is jumped from battery to battery
And the positive is to the switch.

I have ran a seperate power cable opposite side of the boat directly to the 2nd battery which powers the furuno.

Also the earth on the back of the unit i have earthed to a spot on the back of the dash on an earth busbar.

Does the power to the furuno need to be from a battery completely seperate from the outboard power or is it with the negatives connected?

Also same with the earth does it need to be on its own or sharing on the busbar ok?

Cheers

 

[Deep Blue]

Mgfishing,

I would try my best to isolate your "electronics" battery from your Outboard starting battery. When you running that outboard, its clearly getting electrical interference into your electrical system, probably from the Outboard's alternator charging system.

Is the vessel's earth ground sharing with any electronic equipment's negative ground. If they are, you can still get electrical noise and interference. I like connect earth grounds to all my electronics, this can help combat any potential electrical noise and will provide you with a clean and constant negative connection.

- Deep Blue

 

[Mgfishing]

Ok so I’ve got battery 1 which has the engine cable directly to the terminals, then has a large post for the negative, & positive which I have ran thick gauge cable to under the dash where I have a large negative post that feeds all my electronics, & the positive goes to an on/off isolater so I can isolator the dash from the batteries.

Battery 2 just has the furuno connect to it but still has a negative which I have connected to the terminal on battery 1, so that way when I have the battery selection switch on 1&2 I charge both batteries off the alternator & when I’m using my electric anchor winch it draws from both batteries otherwise using 1 it over draws current & my screens turn off.

So reading what your saying, do you think I should charge battery 2, then disconnect battery 2 completely from battery 1 & run the furuno isolated to see if this fixes the problem?

 

[Deep Blue]

Mgfishing,

Yes. What you want to do is completely isolate the battery that is powering your FCV588 from the interference and/or noise that the outboard is generating.

- Deep Blue