Bonding a Hunter 2002 Passage 456?

[discovery]

We were going thru shaft zincs to fast so while we were in Marathon we had SALT send someone out to the boat to do a galvanic survey. We were told the results of the survey was that we had differing metals acting like batteries and to correct this we needed to bond all the metal parts coming into contact with salt water. so we had 6 gauge wire attached to all the thru hulls, strainers etc and tied that into the DC ground. I have recently seen several posts saying this is not advisiable. any suggestions, I don't want to make things worse but SALT is a very well respected outfit so I took the advice. I will look forward to hearing the opinions on this forum.

 

[Don S/V ILLusion]

Think of it this way-
Anytime you connect two metals through a conductive media, you create a battery. You already have the potential ( no pun intended) when in the water which effectively bonds them and the last thing you want to do is exacerbate that condition.

 

[Charles Erwin]

What you describe means that the zinc mounted on your shaft was protecting the shaft/propeller assembly - and nothing else. When you wired all the other things together then to DC ground (necessarily also the motor block and also the shaft/propeller) the shaft zinc now is protecting all the underwater metal in the boat - not just the shaft/propeller as before.

As a result your present zinc will degrade even faster than before -- unless you added more zinc to the shaft (or placed new zinc on the hull wired also to these additional metal items.)

If SALT is well regarded you can expect they conducted hull potential testing and so they should be able to explain to you what those test results showed and how wiring all these things together can be expected to retard zinc wasting.

 

[Don Lucas]

I'm in the don't bond camp! By that I mean don't connect the thru hulls etc to the electrical system anywhere that you can prevent. There isn't anything good to come out of connecting things that aren't suppose to be electrical to those that are.

I had a bad ground connection once that resulted in the holding tank thru fitting corroding away and only being held on by caulking. If there hadn't been a bonded connection all that would have happened is that the fuel gauge would have stopped working. Instead I could have sunk.

If you want to bond the thru hulls together so they are at the same potential, I'm OK with that. As long as they aren't connected to the electrical system.

Since the prop shaft is bonded to the electrical system, and it has different materials, if you think you are going though shaft zincs too fast you should start by checking your engine ground wiring and connections.

West marine has a good article on all this on their web site that is pretty straight forward and easy to read.