Wiring question

[Madmax]

Hello all, newbie needs help....

Just got our first boat at the end of May, and I am trying to make some improvements. Bought some electronics; most have a red and black wire, straightforward, R+ B-, but one component has black, red and white; says R is positive B is negative and the white is ground.

So, question is, what do I connect the white to?

I know in a car 12 V system the black, or negative is referred to as ground. So is it the same on a boat?

Thanks in advance, Max

 

[noluck]

maybe list what the unit is, or a link to the wiring diagram

 

[sly_karma]

Hard to say what it is without more detail, but it could be a standby wire for connection to ignition switch.

 

[Charlie]

If the boat has a ground system. Red (R) goes to positive on the battery. Black (B) goes to negative on the battery. White (W) goes to the boats ground.

 

[Madmax]

No wiring diagram, but below is a cut and paste from the installation manual.

It is a Northstar GPS/Chartplotter.

Charlie, how would I tell if the boat has a grounding system? Sorry if that is an elementary question, but totally new to this.

Thanks.

 

[Madmax]

DOH!

Just read my own post and there it is in black and white....black and white can be connected at the power source.....that's what I thought but just wanted to be sure, didn't want to fry anything the first time I hooked it up.

Thanks everyone who answered.

 

[ericl]

Hi Madmax. Unlike a car, a boat might have an earth ground - water. As an FYI saltwater is a reliable earth ground while freshwater is not. Right below where it says wire white & black together at battery ground, it says if a good earth ground is not available, cap & stow the white wire - which means double-over the end of the white wire & wrap electrical tape around it.
On my boat everything metal and the negative battery terminal are metal-to-metal connected via a string loaded brush on the prop shaft.

To check if you have a similar set-up, you will need a digital ohm meter that can measure 1/100 of an ohm. Take this measurement between the neg battery terminal and some bare metal that is in contact with the water - leg on you O/B, etc. Or have a boat shop that understands what this stuff is all about do it. If they say it doesn't matter, find another shop.