Confused about 12 volt system

[HONKER1]

Just read the posting by Down South (Hooking up 12v DC in A aluminum boat) and I need someone to straighten me out.
I have a 18' Aluminum Starcraft and I've done a lot of wiring to straighten out the mess that was in it from the last owner. I've always ran the ground back to the battery or to a common buss, and then back to the battery ground.
But I know that some grounds are bolted to the aluminum haul, and I believe this has to do with the in floor aluminum fuel tank. But the thing that bothers me is when I connect my 12 volt testing light to the positive battery post and ground to the haul, the test light will shine, This tells me the battery is connected to the aluminum haul or the haul is grounded back to the battery. (Right)
Do I have a problem that should be looked into farther, or is this normal?

 

[Boatist]

Re: Confused about 12 volt system

It normal. The negative lead of the battery is grounded to the engine block or outboard.
All I/O motors I have seen are grounded to the hull with either mounting screws or just a ground wire. Many outboards also.
Even in salt water this will cause no problem but do not use the hull as a conductor.

So do not ground your radio to the hull, run the ground wire back to the battery.
Same with everything else.
You do not want current flowing thru the hull

 

[HONKER1]

Re: Confused about 12 volt system

Thanks for the peace of mind. This website is the best for straight answers, and not blowing things into a big repair bill. Thanks again!!!!!!!!!!!!

 

[Bondo]

Re: Confused about 12 volt system

Ayuh,....

You're confusing Grounding various Circuits,...
With Bonding the Hull,+ driveline components......