Fishing Victoria Forum

rb85 wrote:It can be a dangerous game incorrectly grounding DC on a boat if it’s aluminium due to risk of electrolysis.

Personally I would not and I would be returning any negatives to a main point or to the battery post without worrying about it.

Remember we are not talking about a 240v residential installation so earthing is not something to consider unless your vessel is a little different to the average trailer boat.

You will most likely have your boat grounded via your engine block.

rb85 wrote:
Remember we are not talking about a 240v residential installation so earthing is not something to consider unless your vessel is a little different to the average trailer boat.

I tend to agree but if you are standing on wet metal boat and you have "grounded" electronics and could be using inverters on board, you would want to add a grounding bar which is isolated from the hull.

Are you aware that it is the current that kills and not the voltage?

NMEA is a balanced line, meaning the +/- is a relative signal to each other. By grounding the negative, it is now relative to ground and no longer a balanced line. This is not always possible and depends on the driving circuit of the devices but it is also not uncommon practice as it can reduce the number of wires required. I agree that you can try lifting the green wires away from the batt. Negative and connect them directly to each other to see if it helps however I don't think this is your problem if it is working properly when dry. Get out the multimeter and test voltages at your devices and battery terminals and look for voltage drops that will indicate a faulty connection. A possible reason it stops working in the water is that the current demand for your furuno goes up when the transducer is in the water and creates a larger voltage drop in the faulty wire/connection causing it to drop below the required operating voltage of the markfish.

Where are you located? I may be able to lend a hand if you would like. I'm in the Dandenong ranges, maybe you are nearby?

Cheers,
Mick

Fish-cador wrote:

rb85 wrote:
Remember we are not talking about a 240v residential installation so earthing is not something to consider unless your vessel is a little different to the average trailer boat.

I tend to agree but if you are standing on wet metal boat and you have "grounded" electronics and could be using inverters on board, you would want to add a grounding bar which is isolated from the hull.

Are you aware that it is the current that kills and not the voltage?

Well aware but we are talking about two different scenarios now. Will respond in more detail later but if you were running 240v permanently having exposed steel at the same potential would be recommended for 12v of a battery it’s not a risk

Damn this is getting interesting. Remind me to use a texta to mark fish. LOL.

Rb, what happens if you "ground" a live terminal?

Good one Mick.

skronkman wrote:NMEA is a balanced line, meaning the +/- is a relative signal to each other. By grounding the negative, it is now relative to ground and no longer a balanced line. This is not always possible and depends on the driving circuit of the devices but it is also not uncommon practice as it can reduce the number of wires required. I agree that you can try lifting the green wires away from the batt. Negative and connect them directly to each other to see if it helps however I don't think this is your problem if it is working properly when dry. Get out the multimeter and test voltages at your devices and battery terminals and look for voltage drops that will indicate a faulty connection. A possible reason it stops working in the water is that the current demand for your furuno goes up when the transducer is in the water and creates a larger voltage drop in the faulty wire/connection causing it to drop below the required operating voltage of the markfish.

Where are you located? I may be able to lend a hand if you would like. I'm in the Dandenong ranges, maybe you are nearby?

Cheers,
Mick

Good point mick wonder if briefly running transducer out of water would prove?

Hey Boys, thanks for all your help and suggestions. Fixed!

I think it just came done to the Furuno draining voltage when on water using transducer as was suggested.

I took the Furuno out of the equation wiring it through the mains, then wired the Garmin and Markfish separately. Didn't make a difference with the greens grounded on the black so I just left it the way it was in the diagram.

Or dumb luck/one of my connections was dodgy

Anyway, stoked :a_goodjob: :banana:

Lock this topic lol

Great outcome well done.

Yeah they are a great little device, without it you have to mark on the furuno then enter the waypoint manually in the GPS. The menu layout of fishfinders and GPS in general are cumbersome, and if you are fishing alone stuffing around trying to do that whilst skippering the boat and keeping an eye on your surroundings is not only a pain in the ass but dangerous imo especially if windy.

It seems crazy to me in 2017 when a standardised protocol exists that you even need something like a markfish. I mean I get why they do it, forcing your hand to stick with a particular brand (I.e. Apple) but its pretty poor form I reckon.

Anyway, marking fish with a press of a button without entering a single menu is worth every minute of the time it took to get right as far as I'm concerned