Electrical / Corrosion Question

[Thor]

Hi all,

I've got a 1946 Norwegian built doubleender 36'
She's silicon bronze fastened, Iron keel, monel keelbolts, bronze Pintles and gudgeons.
Couple a years ago, we got rid of our Atomic4 and decided living without an inboard. We love it! She handles beautiful without all that weight.
Anyway, after a 1.5 year haul out, we got a new sternpost(got rid of the prop shaft), 25 new planks, Floor timbers, Keelbolts, etc....

My electrical question : I've got split 12V DC sys. (4x6V) and no A/C at all. Everything is wired from Battery to the load and back to Battery via wires(Simplified description). There is no other elec.ground other than the Neg post on the battery (no plate on the hull, etc...) Batteries are charged by Windgen, Towing gen. and solar panels. Is this an O.K system?
What could be improved?

My Corrosion question: The iron keel is held on by monel keel bolts and protected with RED HAND and Thru-Hulls are Silicon Bronze so are the Gudeons and Pintles. There's no other harware below the water line. There's no Zincs anywhere.
No bonding system either. The metals look good (no evidence of Angel hair) I guess I'm worried that maybe the wood is being eaten away since we found quite a bit of wood burning during our haul out. What can I do to ease my mind ? Any multimeter test i can do to see what's going on?
Thanks for all the info>

[paladin]

I may start an argument...but.....if you are happy with the current (no pun intended) situation, leave it alone. If all the systems are isolated and nothing is returned to a common ground bus electrically you should be just fine...

[Russ]

If there isn't ANY path for electricity to reach the water then I think you should be OK. What I mean is that you say that all wires go between the battery and the load. If neither polarity can find a path to water, then there shouldn't be any electrolysis. The other thing to watch out for is if you connect to shore power, shore cable or shore phoneline which you sort of indicate that you don't. Understand that when I talk about a current path to water it can be really small, on the order of only microamps to get electrolysis started.

A really close and periodic inspection of the entire electrical system is always the most prudent way to go. That way you can detect any problems early and ward off any surprises. For a mulitmeter test to be effective you would have to be able to shut off ALL loads and put an extremely sensitive and accurate ammeter in line to detect current flow that is not normal load related. Not really practical as electrolysis would probably be in the micro or nano-amp range.

[Ed Harrow]

Thor, where'd you find the burning? I ask because, in my limited experience, I've seen reactions between iron and oak that I think could be mistaken for being electrolysis related.

A recent article in our sponsor's magazine dealt with a boat that had been bonded, and the problems caused by the bonding.

[Tom Jackson]

The U.S. Coast Guard's Navigation and Vessel Inspection Circular 7-95 has sections addressing galvanic corrosion and bonding that my be useful to you. Here's a link:

http://www.uscg.mil/hq/gm/nvic/7%5F95/n7%2D95.htm

You might also use the index search function on the WoodenBoat home page to find articles related to this subject. Giffy Full had an important article some years back on bonding, for example.

[RGM]

You don't tell us if you are in a marina or hanging on a mooring bouy, or perhaps something else. Your problem may very well be generated by a neighboring vessel or faulty marina wiring. You've probably already done this but accomplish a hand-over-hand inspection of all the connections and cabling (pay close attention to proper sizing) of your electrical generating equipment. Are any of your connectors or cable securing devices "household quality". If so, replace them with marine stuff. Do the mounts for your generating equipment do a good job of electrically isolating the equipment from the vessel's structure? Good luck.

[Thor]

Thanks for all the replies. Yes, I'm at a marina and yes, everything is marine grade and heatshrunk. We found most of the burnt wood in the old (1946 oak) sternpost. An aquamet prop shaft used to go through it. I will try and look for current leakage.
I'm thinking of installing a Shortwave receiver (NOT transmitter, ssb,ham,etc) will I need to have a ground in order to get good reception? and for good VHF transmition? If so, can I just temporarly clamp onto a keelbolt,etc?
Thanks again.
Cheers

[Thor]

Originally posted by Ed Harrow:
Thor, where'd you find the burning? I ask because, in my limited experience, I've seen reactions between iron and oak that I think could be mistaken for being electrolysis related.

A recent article in our sponsor's magazine dealt with a boat that had been bonded, and the problems caused by the bonding.

Loved your website! Boy, it reminded me of our haul-out