Bonding and wooden boats

Folks,

What is the collected wisdom on bonding systems for wooden boats? I've heard much contradictory advice, but it's leaning about 60/40 toward NOT bonding, due to the galvanic damage it can cause to wood if any stray voltage gets into the bonding system.

I just replaced/upgraded my galvanic isolator on the shorepower system, but I'm considering stripping out the bonding system on my 45-year old wooden trawler. During a recent haulout, I did see some evidence of wood damage around through hulls.

Thanks!

Sorry, but if your boat is 45 years old and you are just now seeing “some evidence” of damage, the system works.

Do not assume "the system works" unless the system is tested. The resistance between bonded items must not exceed 1 ohm. The bonding system needs to be free from corrosion on terminals and good solid connections in order for the system to work properly otherwise damage as you describe may result. Bonding systems are often neglected.

The "do not bond a wooden boat" camp wins hands down in most Maine harbors.

We are not bonded for over 40 years

My current wood boat has a copper plated bottom, bonding everything together. Most of the thru hulls/seacocks are from 1942 and still in excellent shape.
I've always use bonding going back to the early 1960s. I normally run a heavy brass solid wire on top of the keelson with similar wires coming from each bonded item. When I do the bonding, I weld the connections to avoid future corrosion. Usually each metal item is bonded and protected by a zinc, including any struts, rudders, shafts, props, and shaft housing. I also have brass brushes that runs on the shafts. I've never had a problem.

In nearly 30 years of shipwright work in the NW, I have seen way more damage done by bonding than not. Done properly its fine, overdone and damage will happen.

Xsbank said:

Sorry, but if your boat is 45 years old and you are just now seeing “some evidence” of damage, the system works.

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Damage is relatively recent and rapid, so I think I have a ground problem. However, the bonding system would seem to serve as the conduit for the electrical ground.

I'm leaning toward removing most of the bonding system. I do have an ElectroGuard system, which seems a pretty elegant solution for shaft protection. I'm considering also keeping the rudders and struts bonded also.

I disconnected all bond wires to through hulls only. I left the rudders bonded. And the metal fuel tanks need to remain bonded. Same wire runs from tanks to shaft log on my boat, I left that.

The only damage since 1970 was several through hull holes in the wood had been partially eaten. I came out to boat back in 2000 and heard lots of water gushing in and the pumps running. A backing block had disintegrated on an engine through hull, and the scoop had fallen down 3/4 into the water, so all round the pipe, water was rushing in. Had to haul out and fix it. The wood was crumbly and channeled round the thru hull. I wire brushed it clean to solid wood and epoxied in a piece and on the inside a solid block attached. Then I moved the through hull to a better spot.

Boat needed a haul out anyway and that was the first haul with me as the owner. Since I sealed the wood hull, I have had no problems at all with through hulls and the wood.