Bonding Questions

[ak-guy]

I like to think of myself as a moderately smart guy but all the bonding/grounding information on the web has seriously confused me.

I have rewired my boat completely with no major problems or confusion except for bonding. It is a small 26' grp boat with a basic bonding system dating from early 80's when it was built. The bonding system connected an external hull zinc to the copper keel cooler to the engine block. The keel cooler also has a bolt on zinc. The stainless prop shaft/bronze prop w/zinc has a new flex coupling that it didn't have before so is isolated from the engine. The only other underwater part is the stainless rudder and shaft, not bonded but with a zinc.

The boat does not have a full AC system. I do have a permanently mounted hard wired marine battery charger but it is only connected via regular ac extension cord (household type plug). The boat will be kept on a mooring with only rare connection to shorepower.

From what I have read it seems I could remove the bonding wires and just have zincs on underwater metal.

 

[Edelweiss]

A lot of boats were never bonded by the manufacture. Mines a 1976 model, not bonded and permanently moored in saltwater with shore power running a smart charger full time.

I'm in the PNW, two zincs on both shafts and one on each rudder and they last a full boating season and I've never had any electrolysis on bronze thru hulls, which are not bonded. If it was originally bonded, then I would leave it. If not bonded and you're having no problems then leave it un-bonded.

 

[Donna]

A lot of boats were never bonded by the manufacture. Mines a 1976 model, not bonded and permanently moored in saltwater with shore power running a smart charger full time.

I'm in the PNW, two zincs on both shafts and one on each rudder and they last a full boating season and I've never had any electrolysis on bronze thru hulls, which are not bonded. If it was originally bonded, then I would leave it. If not bonded and you're having no problems then leave it un-bonded.

And this is one of the problems of being at a marina. You never know what kind of bonding if any the boat has next to you. I was replacing my zincs EVERY month so I decided to check my bonding. Lo and behold a thru hull fitting that was replaced 3 weeks ago in the Bahamas was showing some discoloration. Re-bonded/grounded, (even with copper screws) and left the marina.

 

[Bigsfish]

I'm not sure there is a perfect answer to bonding. One boat I had for over 20 years had zero bonging. No problems.
Another boat was partly bonded (not 100%). No problems in 15 years.
Current boat is totally bonded. No problems after 3 years.

 

[Benthic2]

When I saw the thread title I figured I'd suggest holding hands around a camp-fire and singing "Kumbaya"..... but I guess we're talking about a different kind of bonding.....

 

[foggysail]

If possible, folks should test their bonding using a half cell. There is an assortment of metals used, mine is a silver-silver chloride half cell but each type half cell has its own voltages as measure against different metals. the measured voltages give indication whether that particular metal is protected or not.

The advantage a half cell offers is that one can reasonably test each wetted metal that penetrates the hull into the surrounding water. Adding a sacrificial metal (anode) to exposed metals causes a negatively shift in the metal's voltage... ie, they are short circuited to the exposed metal. Electrons flow from negative to positive.....current's direction was defined back in the late 50's to flow from positive to negative and only confuses matters. The greater the negative voltage with reference to the half cell using a reference chart, the better protection that metal has to galvanic corrosion.