electrical bonding

[distantdrummer]

Having lost a keel bolt to some sort of exotic corrosion, I have decided to replace the entire bonding system.
And promptly run into a puzzle. I read where all the experts declare that the bonding system and the DC negative must absolutely be kept entirely separate. So far, so good. I ask, though, is not the prop, the shaft and the engine part of the bonding system, and, at least on my boat, the DC negative current runs via an engine-mount back to the negative terminal of the batteries.

How does someone who understands a lot more of all this explain the contradiction?

[distantdrummer]

Rick,

ahhh, lightining protection ! NOW I get it !!!!
Would you per chance know the author and title of a good book on the subject of bonding. I need to study the matter. Thanks.

Frank

[IslandRaider]

OK, Rick now ya lost me, if I bond to the engine and the negitive side of the battery bank/ charging system is bonded to the engine the potential IS the same because if I then measure voltage between pos an neg on the battery or pos on the battery and say the mast the differance of potential is exactly the same.


Frank. try reading the Boat Owners Mechanical and Electrical Manual
By Nigel Calder

There is are different schools of thought on grounding and bonding and for every 1 person for it there can be 1 against.

Research shows boats with lighting protection are more prone to strikes but suffer less damage because the give a path to ground. boats without suffer less strikes but when they are hit you can usually find them on the bottom.

[sailingdog]

There are two different situations where people discuss "bonding" systems on a boat.

The first situation is when you bond the equipment together for lightning grounding and protection. In this case, the equipment definitely should be grounded to the DC electrical ground. The second is when you bond the underwater metal components for galvanic corrosion protection.

This is a situation where you wouldn't want to ground the "bonded" components to the DC ground, since that would increase the possibility of DC-system related accelerated galvanic erosion.

[distantdrummer]

Rick,

it is the galvanic/electrolytic protection of shaft, through hull fittings, etc. that concerns me, as, as has been pointed out, that is an entirely different breed of cat...

I still dont know whether the anti-electrolytic bonding should or should not be connected to DC ground. I hope, Nigel Calder will tell .

As to smoking, and its dangers, well, true, but, you have to measure that risk against the pleasure it gives you (if that is the case). That is so with all our little pleasures in life. After all, saiing can lead to all kinds of death, too. Just think of the ozone hole up there !!! Or shark bite???

Frank