GW Bonding

[Hookup1]

Helping a friend out with a bonding problem on his boat got me thinking about mine. From what I remember I haven't seen any bonding wires on any of my bronze thru hulls. Only zincs I have are candy bars on tabs and u-shaped ones on engines.

 

[Meanwhile]

When I bought my Marlin in 2014 I asked GW about bonding, they wrote it was not necessary, but if I wanted it to contact a marine electrician. End of story.

 

[ElyseM]

same. GW told me no bonding on outboard powered boats.

 

[Hookup1]

Having a boat connected to dock AC power is more likely to create a stray current that eats the metal. The more AC use on the boat for refrigerator, air conditioner, etc. the more you need zinc plate, bonding and galvanic isolator (which all GW's have). Also inboards have more metal in the water.

I have a bow thruster, 4 thru hulls and outboard zincs that are almost dry while sitting. Two trim tabs are zinc'ed. I guess i'm ok!

Halo's created by galvanic action eating the copper out of the paint on my friends boat.

 

[ElyseM]

i do not leave dock power on when I'm not at the boat. gunwale and lighthouse switches off. could be why I've been relatively good. ron

 

[Fishtales]

The only wires I have seen are on the yamaha engines. Good to check these every year before splashing to ensure connection, they are fairly light gauge wires.
There are usually 3 sets of zincs on the motor. One on the lower unit usually dual purpose trim adjustment, the bars in the mounting and a set of internal ones.
I've seen some installed on trim tabs and some don't have them like the thru hulls.
If you have a bow thruster or other in water equipment, you'll likely have one there as well.

 

[seasick]

i do not leave dock power on when I'm not at the boat. gunwale and lighthouse switches off. could be why I've been relatively good. ron

You don't need to have the power on to potentially (pardon the pun) have galvanic action. Having shore power chord connected even with the breaker off at the dock can still contribute to ground currents. More often than not at my club, it is stray currents at the docks that are the major contributor to galvanic action on boats. If you zincs get eaten quite quickly, and you are not on shore power, you need to look for stray currents in the water. There are calibrated ways to do that and not so calibrated ways that can show more extreme cases.
Note also that incorrect bonding wiring can result in more stray currents than no bonding.

 

[ElyseM]

You don't need to have the power on to potentially (pardon the pun) have galvanic action. Having shore power chord connected even with the breaker off at the dock can still contribute to ground currents. More often than not at my club, it is stray currents at the docks that are the major contributor to galvanic action on boats. If you zincs get eaten quite quickly, and you are not on shore power, you need to look for stray currents in the water. There are calibrated ways to do that and not so calibrated ways that can show more extreme cases.
Note also that incorrect bonding wiring can result in more stray currents than no bonding.

agree, but hopefully the galvanic isolator does a relatively decent job. for me, so far, so good. ron

 

[seasick]

A galvanic isolator is a very good solution to reduce stray currents. They do go bad once in a while so checking should be part of your annual routine maintenance.
Here is an article from Boating Magazine that is very helpful

Testing a Galvanic Isolator | Boating Mag

Perform this test on galvanic isolators to ensure their proper operation.

www.boatingmag.com

 

[Angler Management]

All correct. FYI my electrical is "grounded" to the starboard engine. I found this out when I accidentally hooked up some incorrect leads off a battery and happened to notice my starboard prop bubbling when I went to the truck. Some research on diagrams showed me this. I live in a "hot" marina and noticed one zinc getting sacrificed faster than the other. I now often connect both motor bracket zincs with a wire, seems to even out the zinc corrosion. Not sure if that's good or bad. But for the good of the order I thought I'd mention it.

 

[seasick]

All correct. FYI my electrical is "grounded" to the starboard engine. I found this out when I accidentally hooked up some incorrect leads off a battery and happened to notice my starboard prop bubbling when I went to the truck. Some research on diagrams showed me this. I live in a "hot" marina and noticed one zinc getting sacrificed faster than the other. I now often connect both motor bracket zincs with a wire, seems to even out the zinc corrosion. Not sure if that's good or bad. But for the good of the order I thought I'd mention it.

What type of motors? Outboards? If so, do you leave them down when docked? Do you have shore power connected?

 

[Angler Management]

What type of motors? Outboards? If so, do you leave them down when docked? Do you have shore power connected?

These were my previous Yamaha outboards. I leave them up unless I'm doing work (as I was when the battery issue happened) or when we get a freeze. I do use a shore power cord. I like the isolator idea. The Zincs I mentioned that corrode are the ones on the outboard bracket and they are in the water constantly.

 

[seasick]

In your earlier post you mentioned that a battery was incorrectly wired and you noticed bubbling on a prop. So, user error, not a bonding issue. Don't confuse shore neutral wiring with shore ground wiring. They are not the same thing.
I suspect that your issue of uneven wear on the motor zincs was due to a bad ground connection somewhere on a motor. Perhaps the zing was not bolted correctly or the small ground wire that connect the fixed parts of the motor mount to the moving parts was bad, broken or missing.
Take a look at your sea cocks to see if there are bonding wires connected to them. If not, your boat is not bonded and you should not add ground wires to equipment unless there are specific instructions for that equipment that says to do so.