What is a "floating" electrical system?

[Navatech]

One of the first pages of my electrical manual (thanks Chris!!!) has the following warning printed:

32 VDC SYSTEM - This is a "Floating" system - neither the negative or positive wires are grounded anywhere in the boat. Such a method minimizes stray currents that can cause serious corrosion problems. It is very important that the "Floating" condition be maintained. Do not add any 32VDC electrical or electronic equipment that is "Case Grounded" to either negative or positive power wires.

Can somebody explain to me what this means?!... And explain how I can make sure that the "Floating" condition has been maintained?!...

[CaptPatrick]

It might be better called "an isolated" electrical system... As the statement is printed, "Do not add any 32VDC electrical or electronic equipment that is "Case Grounded" to either negative or positive power wires" means just that.

Test using a multimeter the + & - battery terminals for connection to your bonding system. The two must not be connected in any way or you'll have stray current affecting all of your bonded gear...

[Navatech]

Test using a multimeter the + & - battery terminals for connection to your bonding system. The two must not be connected in any way or you'll have stray current affecting all of your bonded gear...

Would I be looking for voltage or continuity on the multimeter?!...

Also, unless I'm mistaken, the grounds from batteries, engine, switch-panel negative bus bar, bonding system, auxiliary power generator and ship's 120 Volt safety-ground all have to meet at one point... Doesn't that contradict the above?!...

[Bruce]

Use the ohm function to check between your electrical ground and the bonding system to see if you have a connection.

Drop a wire in the water on one meter lead and the other to the bonding system to check for voltage between the two. If the meter auto ranges, then okay if it does not put it on the lowest scale.

If you have a connection in any way, shut the power feeds off for everything and one by one turn each thing on to check for problem circuit all the way back to the dock breakers.

If nothing changes when you shut everything off, you could be picking up stray stuff from another boat or the marina.

Modern day electrical systems on fiberglass for the most part do not use floating electrical and can tie grounds to the bonding system on both ac and dc systems.

Floating or isolated ground systems using an isolation transformer are standard practice on aluminum and steel hulled boats.

[Navatech]

When I rewire the boat for 12/24 volts I'll implement all the modern stuff... In the mean time I want to be sure I'm not breaking anything... And to make sure the PO didn't break anything...