Bonding

Justinf89 · Post by **Justinf89** » Thu May 08, 2008 11:45 am

I have a big bonding problem on my 77' 33 fbc and was wondering if anyone knows what I should do. When I bought the boat, during the survey, I noticed that there were quite a few thru-hulls that were pink along with the stbd engine scoop. I investigated and found that it is a bonding problem. My boat does not have a transom zinc and I was wondering If I should put one in? A lot of my thru-hull valves do not even have bonding wires going to them. Should I clamp some on? I've tried my best fix what I could with a multimeter. Also, the rub rail on the outside, should it be bonded? At every joint, I checked each to engine ground and none were. Around the inside of the boat, there are little jumpers connecting it all together. Thank you for the help, Justin.

buzzk · Post by **buzzk** » Thu May 08, 2008 1:51 pm

I'm sure some of the guys will answer that know more about the subject. I haven't had any problems and don't know that much about it. But I do know that all the thru-hulls should be bonded. Buzz

franklyprice · Post by **franklyprice** » Thu May 08, 2008 3:04 pm

Justin, Not sure if all years had everything bonded but my '87 does. All metal on the boat is connected to the bonding system. I mean every piece of metal including the grab handles. On my transom is a large zinc that looks like it was added much later so I am guessing that the bonding system originally relied on all the metal under the water line to dissipate the current. The problem with that is that as the boat ages, a few bonding wires let go and before you know it you have one or two through hulls doing all the work, probably shortening their lives a lot. I would recommend the large zinc on the transom. Seams to work well.

captgene · Post by **captgene** » Fri May 09, 2008 4:46 am

Justin, I have a 89. I'm sure they did this prior to my year. There are copper strips imbedded in each stringer. In each compartment they didn't glass over the strip , and there are connections. Every thruhull , water tank, pump...whatever had a ground running to this strip. Yep, rubrail, grabrail, even the exhaust mailboxes, my half tower too. In the generator compartment at the end of the strip, is wired to the transom plate. I also have shaft zincs and trim tab zincs. I remember when I bought the boat, I had to fix almost every wire too. Even without the embedded strips, you could get the same effect running a heavy ground through the boat and incorporate a few terminal blocks for connections. Adding a plate to the transom would be pretty easy. Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC

Justinf89 · Post by **Justinf89** » Fri May 09, 2008 5:44 am

So adding a transom zinc is a good idea, what about wires from each strip running to it? How big should those be? Also, I have come across a new problem. On the port side, where a wire runs from the bonding strip to the port engine mount, where it screws to the stringer, is a problem. I measured continuity from the bottom of the mount to the top of the mount(or anywhere on the motor) and it has 7 megaohms, like there is an extreme amount of resistance between the mount. This is a problem because the bonding wire connected to the bottom of the mount, is not very well connected to the rest of the motor. Are these motor mounts cushioned so that it isn't metal against metal or do I just have a mount that is going bad inside with corrosion maybe? I was thinking about moving the wire to a bolt on the block, what do you guys think? Thanks for the help, Justin.

buzzk · Post by **buzzk** » Fri May 09, 2008 5:50 am

When I bought my boat she only had zincs on the shafts. She did have a galvanic isolator and still does. I added zincs to my rudders, trim tabs, and swim platfoam. I don't have a transom zinc. I'm not sure that I need one because my zincs seem to last a long time. I have a diver clean the bottom once a month and he checks and replaces any zincs as needed. All my metal is grounded. Every now and then I'll have to replace a end on a wire. Buzz

JohnD · Post by **JohnD** » Fri May 09, 2008 12:09 pm

Justin, On my 1972 B35 everything is bonded and I've redone most of them. The original copper strips have been damaged and for now I used 10ga wire to connect everything to the grounding plates in the bottom of the boat. I don't have any transom zinc's and would consider them optional if you've got a good bonding system. So if you've got grounding plates mid-ships or there about, I'd just make sure everything ties into them with a 10ga or larger wire, some say 8ga. I think Defender has about the best price on the copper foil for grounding. If you don't have it already, you'll want to get a copy of Nigal Calder's book "Boatowner's Mechanical & Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems " its a great reference. br,

smanni · Post by **smanni** » Fri May 09, 2008 5:01 pm

I had an entire new bonding system put in last year using terminal strips mounted at strategic locations. You would be surprised at how many of the connections between the stringer mounted coppers strip and their intended target were bad.

Justinf89 · Post by **Justinf89** » Sun May 11, 2008 2:16 pm

Looks like I have many problems connecting to the bonding strip that need to be addressed. Some of the copper strip is even pink, which I traced to not being properly bonded to the motors. They are bonded via the bottom of the motor mount which is not connected to the rest of the motor? Kinda weird but I moved it.

captgene · Post by **captgene** » Mon May 12, 2008 4:38 am

Justin, It almost sounds like you have a short in 12v somewhere feeding back through the system. But I've seen a lot of marinas with 110 hanging in the water somewhere. Many marina slips with grounds corroded off the power boxes. You name it. I had a neighbor with a Carver that just cooked the zincs off my boat. I traced it to his dock, but he denied it. Once he sold that boat, my problems went completly away. Guess what..he got a new smaller boat this year and sure enough, My outboard shaft zinc seems to dissappear in 3 months. The zincs were lasting a year before. Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC

Justinf89 · Post by **Justinf89** » Tue May 13, 2008 2:11 pm

Any ideas about a galvanic isolator? The marine the boat's at currently is kind of cheap and let go. Any brands to keep in mind? I was thinking about picking up a 30amp one off of ebay because I don't use shore power line 2. I usually run the AC off of line 1 and just don't use anything else when I have to.

buzzk · Post by **buzzk** » Tue May 13, 2008 3:22 pm

When my old galvanic isolator died I bought my new one from these guys www.yandina.com. Go to the Bertram 31 web site look under building tips and then look for galvanic isolators. There is a lot about installing them there. Buzz

lobsta1 · Post by **lobsta1** » Tue May 13, 2008 4:11 pm

Buzz, First year Nites Off was eating up zincs. Also bought from Yandina. Zinc usage was cut about 40%. Al

Justinf89 · Post by **Justinf89** » Wed May 14, 2008 10:01 am

I was looking at this one on ebay. http://cgi.ebay.com/ebaymotors/ProMarin ... otohosting I'm sure it won't go for a decent price but I'll watch it. I assume it's a duel 30a model, which would be perfect. Where did you guys install yours?

buzzk · Post by **buzzk** » Wed May 14, 2008 11:59 am

Justin, mine is located in the area where my holding tank is located. Under the electrical panel in the salon. Buzz