Bonding system for underwater parts

yorklyn · Post by **yorklyn** » Sun Feb 19, 2012 12:19 pm

The old bonding system on my boat was a complete mess. I have purchaced numerious books but have yet to find one that explains how to set up a bonding system in terms I can understand. I'm trying to find out what gage wire should be used? I know all underwater metal parts should be hooked together in a series and then connected to a large zinc on the stern. I know there is a bonding bar in the bilge that I believe is a conecting point for the battery ground? does the bonding system also get connected here? If anyone knows how to explain how to this system works I would be very grateful!
Thanks

Big D · Post by **Big D** » Sun Feb 19, 2012 3:31 pm

8 gauge minimum. I like to use 6. Should be green insulation for proper identification. Don't hook up direct to battery ground but should be bonded to the engine block as well, and rudder hardware, strut, shaft stern tube etc, as well as all the through-hulls of course. Deffinately a confusing subject. Did your head blow up yet? Then there is the controversy on whether we should be doing it at all

alexander38 · Post by **alexander38** » Sun Feb 19, 2012 3:48 pm

I've seen yes on glass boats and no on wood..on the wood read it some where it can have a bad affect on the wood around the thru hulls

prowlersfish · Post by **prowlersfish** » Sun Feb 19, 2012 3:55 pm

There is 2 schools of thought on this ,( to bond or not to bond) they both make sence But mine came that way and ithe worked for 35 years so it will stay that way .

Big D · Post by **Big D** » Sun Feb 19, 2012 3:56 pm

Deffinately a no no on wood but still controversial on glass.

alexander38 · Post by **alexander38** » Sun Feb 19, 2012 4:01 pm

prowlersfish wrote:There is 2 schools of thought on this ,( to bond or not to bond) they both make sence But mine came that way and ithe worked for 35 years so it will stay that way .

Ditto..

MadBen · Post by **MadBen** » Sun Feb 19, 2012 4:05 pm

Big D wrote:Deffinately a no no on wood but still controversial on glass.

I'm confused now. Why the difference in opinion. I thought bonding was a must. This will be a learning event for me.

Big D · Post by **Big D** » Sun Feb 19, 2012 4:06 pm

prowlersfish wrote:There is 2 schools of thought on this ,( to bond or not to bond) they both make sence But mine came that way and ithe worked for 35 years so it will stay that way .

That's correct Paul the two schools of thought are basically:
- Bond everything and protect
- Unbond everything and isolate

ABYC favors bonding everything but does state that electrically isolated through-hull fittings need not be isolated.

yorklyn · Post by **yorklyn** » Sun Feb 19, 2012 4:10 pm

Big D, When I originally reasearched bonding my head did feel like it was going to explode! Seems to make sense to tie all underwater metal together to prevent any one piece from being rapidly destroyed. with the zinc tied into the loop it should get attacked the most.
I could swear the remaining "hacked" bonding wires on my boat tied into a grounding bar that was attached to the battery box? (I'm really looking forward to sorting out the wiring!!!!!)

Big D · Post by **Big D** » Sun Feb 19, 2012 4:23 pm

MadBen wrote:
Big D wrote:Deffinately a no no on wood but still controversial on glass.
I'm confused now. Why the difference in opinion. I thought bonding was a must. This will be a learning event for me.

Not all vessels have the type of bonding we're talking about. Most manufacturers do though. In an isolated configuration for example, you'd have to isolate the shaft from the engine block by installing an isolating flexible coupling between the shaft coupler and the tranny flange to electrically isolate the block from the shaft that's in contact with the water. I say, what ever system you have in place now that is OEM, keep it that way unless you're willing to consult someone who knows this stuff, it can get complicated and dangerous if not done right. You folks in salt water; I'd be checking all your bonding wires and connections/terminals for good, clean solid connections.

MadBen · Post by **MadBen** » Sun Feb 19, 2012 4:35 pm

OK, now let me get this right. The factory system is correct and not to be screwed with. The boat is safe. Just maintain the connections. Right?

Big D · Post by **Big D** » Sun Feb 19, 2012 4:37 pm

Right, unless you're having a real problem with corrosion, then there may be something wrong.

jefflaw35 · Post by **jefflaw35** » Sun Feb 19, 2012 4:43 pm

my bayliner has the wire leads on the outdrive, but this trojan has nothing connecting one component to the next, trim tabs and rudder just have zinc bars, i will have to research a pic to understand this one

Big D · Post by **Big D** » Sun Feb 19, 2012 4:55 pm

Same deal with the stern drive Jeff. They are called continuity wires. They connect each component that would otherwise be electrically isolated such as bell housing, gimble ring, transom assembly and so on including the steering linkage inside the boat and onto the block. Even the Merc bellows have metal tabs to connect the clamps into the circuit. If any of these are missing or broken, they should be replaced.

jefflaw35 · Post by **jefflaw35** » Sun Feb 19, 2012 5:06 pm

i understand now, i would i assume when i get this equipment cleaned up i will find the holes where the wires used to attached, I did a gimble bearing on the bayliner alpha one last year and replace all of it. that out board if i remember had 6 or 7 zinc bars but shes always clean no matter how long i let it sit in the water.