Check Your Bonding System-gctid383113

[Guest]

We checked our zinc bonding system today with a corrosion tester we have at the yacht club. We typically do this annually in the spring about 2 weeks after changing our zincs to make sure they are working effectively. Without getting technical, the tester (volt meter) is connected to an electrode that is placed outboard in the water, while the other electrode is used to systematically clamp onto the various boat parts that are connected to the bonding system, such as rudder post, struts, thru hull fittings, shafts , and engines. (There are at least 14 connection points on our system). Observations during the test indicated that all connection points were adequately protected except three: port rudder post, one thru hull fitting, and the starboard strainer. The rudder post bonding wire connection had come loose (don't know why), and the other two just had bad connections to the bonding wire which needed to be cleaned up.

So, just changing your zincs annually may not be enough. You also need to make sure all of your connections are good, or parts of your boat will be freely corroding, even though you have new zincs and a bonding system. How many boaters out there are regularly checking this? Actually, I will be stepping up my program to twice each year. Doing it in the late fall will also confirm whether I have sufficient protection left after the summer to last thru the winter. If the fall protection reading shows up as marginal, another zinc change will be needed for protection until spring if the boat is kept in salt water.

It would be interesting to hear what other BOC members do to ensure the their bonding system continues to work effectively. How many do not check?

[Guest]

Bob,

I couldn't agree with you more.

Now, let's get technical. What are the details on the tester you use?

[SomeSailor]

It's called a silver half cell. You can use an ordinary DC multimeter and a strip of silver (most jewelery craft stores). You attach the piece of silver to one end and your bond wire to the other.

they sell specialized testers that use a silver chloride half cell as a reference, but you'll be able to see a bad connection easily with a multimeter too.

[Guest]

RJH wrote:
Bob,

I couldn't agree with you more.

Now, let's get technical. What are the details on the tester you use?

What Somesailer says.

Our yacht club purchased a testing kit a few years ago for members to use. I believe it costed about $400 at the time. It comes with a booklet about the subject of bonding, and instructions on how to use it. The analogue guage is calibrated to indicate the degree of protection being provided for bronze and for steel. As Somesailer says, you can make a multi meter work as he described, but it would also be good to know how well the protection is working for each metal. With the multi meter, it would be good to have a companion reference book on the voltage range needed for bronze and steel protection.

Hope this helps with the 'technical' stuff.

[Wild_Blue_Yonder]

I just redid my bonding system. Even though I change zincs annually,I had some burning of the paint around the toilet thru hull and one engine seacock. Found bad connectors and wire in several places. I cut off connectors and cut back the wire to the non corroded sections. On the other side, I just replaced all the wire and connectors. Replacing the wire was much easier and faster. The wire is no. 8 green and ran around a dollar twenty a foot. Now have perfect, zero ohm connection on all parts on both the left and right systems.

Jim