Kevin,

I have a 1978 30′ Tollycraft boat. It has twin engines and a closed cooling system that takes in raw water via thru hull fittings which is then pulled through the closed cooling system via raw water pumps.

The boat is berthed in a marina and is connected to 120 volt shore power when berthed. It has four batteries, that are charged via engine alternators or a 120 volt battery charger. It does not have a generator. When needed, I use a portable Honda generator. It has standard electronics (GPS, fish/depth finder, VHF radio), a 120 volt refrigerator and a 120 volt water heater,

I noticed the original bond wire from the pumps and other parts of the drive train have broken off or were not connected properly.

I’ve heard some mention to run a heavy copper pipe the full length of the boat and what ever needs to be bonded is connected to the pipe which eventually is connected to the bonding plate, or that wire and bus bars are used. What items need to be bonded, and what is required to bond these items correctly?

I presume all bonded items make their final destination to the bonding plate located at the transom. Is that correct?

Please let me know.

Thanks,

Chuck

Chuck,

It is no surprise that your original bonding wires are starting to rot/corrode off. They were probably made from straight copper wire as compared to tinned boat wiring.

You certainly can run a copper pipe through the hull of your boat as a common bonding point, but it is very difficult to install when the boat is completely built. You will also increase the number of connection points in your bonding system that are difficult to get to and inspect.

My preference is a common bonding bar with individual (in most cases) bonding wires running to every underwater, metal device. This is connected to the engine negative (or its bus) and also to your bonding plate.

Wires fail at connection points. A common connection point is much easier to inspect.

Hope this helps,

Kevin

Hi Kevin,

Thanks for getting back to me.

Yes, that is correct they used a straight single copper wire for the bonding, versus tinned stranded marine wire. They ran the bond wire from the bonding plate to each item, drive shaft packing flange, engine, transmission, and raw water intake valve and filter assembly. No common bonding bar where each device is connected to and the bond bar is connected to the bonding plate.

So now that you know what type of flawed system I have. My original questions still exist.

1. What needs bonding?
2. What needs grounding not bonding or vise versa?
3. What type of common bus bar should I use (what do you have to sell)?
4. How are the bonded items connected to the common bus bar (stranded tinned wire with a gauge of? and connected by means of ?)? Standard rules of thumb for wire gauge and type?
5.  How is the common bus bar connected to the bonding plate (stranded tinned wire with a gauge of? and connected by means of ?)?
6. Should I use any type of protectant on the wires and connectors (dielectric grease, anti oxidant grease, etc.)?

Please let me know.

Chuck

Hi Chuck,

Here is a posting of the ABYC marine wiring standard that explains how to install the system and what items to bond.

Hope this helps,

Kevin

Hi Kevin,

Thanks for the standards.

I looked over the section on bonding and grounding. I’m still confused of where the final ground destination is. The information stated the negative terminal of the battery goes to the engine ground, however the schematics show the engine goes to a ground. Where is the engine grounded to, the bonding plate/anode located at the transom or other? Please clarify

I’ve also seen a lot of conflicting information on what type of wire goes from the bus bar to the end ground source. Many articles say #8 primary stranded tinned wire can be used but the run should not exceed 2′ in length. If that is so, how do you go from the bus bar back to the final ground destination, battery or bonding plate, which would be a lot more than 2′ in length?

Please clarify.

Thanks,
Chuck