Help utilizing a water ground

[tgr23]

My gps/sonar picks up static when I accelerate and Garmin recommends a water ground for the unit. What are the suggested areas to ground to on my 258? I'd rather not have to run a ground all the way to the stern.
Thanks

 

[seasick]

My gps/sonar picks up static when I accelerate and Garmin recommends a water ground for the unit. What are the suggested areas to ground to on my 258? I'd rather not have to run a ground all the way to the stern.
Thanks

I am not sure what a water ground is.
You say that you get static when you accelerate. Is it just when speed is increasing or is there static at higher speed?
Static ( I guess you mean noise on the display) can come from the transducer cable OR the power cable. One way to check is to unplug the transducer connector and accelerate. If the screen displays noise, the problem is on the power side most likely.
If it only happens on with the transducer connected, you could have a bad cable or connector or more likely electrical interference introduced into the transducer cable. Unfortunately, if it is interference, the only real way to eliminate it is to relocate the cable.
On the other hand, noise introduced on the power cable can be helped with filters.
Note that if this problem is new and wasn't happening before, something has gone bad.
Bad ground connections anywhere can cause an electrical noise situation. Bad or corroded connections on ground or positive feeds cab also cause issues. Changing resistor type spark plug cables with non resistive ones can cause all sorts of noise. Bad rectifiers can do the same too. Bad spark plug cables can cause noise too.
Sorry I can't be more help but these things can be hard to isolate and fix especially if the problem has always been there since you don't know what may have changed.

Easy thing to try (maybe easy) is to check all power connections, fuse holders, bus bars, battery and battery switch connections etc to make sure there are good tight and clean connections

 

[fellinger]

I think the only true water ground is a device like a Dynaplate or outdrive. Could you use a through hull sea cock that is all brass, like the scupper for the head fill?

 

[Harpoon]

Would an outboard motor not be a good water ground ? All grounding is already attached to it .... Maybe you have a bad connection somewhere

 

[ElyseM]

i believe the dynaplate primary purpose is a grounding plane for SSB, but not an expert.

your system is already water grounded via the engine. you might want to introduce some ferrite chokes, but at a minimum, go thru the process seasick laid out. good luck, ron

 

[tgr23]

That is a great diagnostic plan.

I get a burst of static when either motor is throttled up, and then it goes away. So on the sonar it reads like a strong band of static then clears up completely once I am no longer accelerating.

The unit is a Garmin 7608. It was installed end of the year last year and i don't remember it doing this. One major change this spring is that I added a third house battery and a Blue Sea battery switch and two ACR's (Automatic charging relay). So there are a lot of new power cables running in the motor well area. I've relocated the transducer cable as far from the batteries and ACR's as far as possible and put numerous Ferrite Core filters on the transducer cable, by the unit and back in the motor well. No difference.

Nothing changed in the engines, same plugs and plug wires.

The only thing I haven't done is this "water ground".

Back at the boat this weekend and I'll start going through the diagnostic list.

Thanks!

 

[seasick]

That is a great diagnostic plan.

I get a burst of static when either motor is throttled up, and then it goes away. So on the sonar it reads like a strong band of static then clears up completely once I am no longer accelerating.

The unit is a Garmin 7608. It was installed end of the year last year and i don't remember it doing this. One major change this spring is that I added a third house battery and a Blue Sea battery switch and two ACR's (Automatic charging relay). So there are a lot of new power cables running in the motor well area. I've relocated the transducer cable as far from the batteries and ACR's as far as possible and put numerous Ferrite Core filters on the transducer cable, by the unit and back in the motor well. No difference.

Nothing changed in the engines, same plugs and plug wires.

The only thing I haven't done is this "water ground".

Back at the boat this weekend and I'll start going through the diagnostic list.

Thanks!

Do the test and see if you need ferites on the power cable to the chartplotter.
While yo are at it, check all grounds for the new house battery and note that all grounds should terminate at a common point. Running multiple grounds can lead to ground loop currents and all kinds of problems

 

[tgr23]

I'll do another check on the grounds too. I installed bus bar for all grounds so I'm covered on everything terminating at the same point.
Thanks