Massive Zinc Usage!

night0wl · #1 (**permalink**) 03-22-2009

Hey All,

I'm a new owner of a 2008 Beneteau 343, and just recently I had my bottom dove on for the first time, and this is what my diver found. Keep in mind, I only brought the boat home to my dock on/around Feb 10, 2009...and its only 1.5 months later:

I think this is my new zinc from west marine (but not sure):

Anyone know what could be causing this sort of zinc usage? I leave the boat under shorepower 24x7...is there a bad ground somewhere? How do I prevent damage to my thru-hulls and metla components under the water line.

I also bought one of those zinc groupers, but I have no idea how/where to install it.

JohnRPollard · #2 (**permalink**) 03-22-2009

You indicate that shore power is connected 24x7.

What is the shore power powering?

Do you have a battery charger that is connected to shore power and running continuously? If so, I would begin by leaving the charger turned off for a month and then re-check the new zinc.

If the shore power is only connected for the battery charger, you could disconnect it during this time period. But it would be more interesting to leave it connected, to help eliminate possibilities. The process of elimination gets muddied if more than one variable is changed at a time.

night0wl · #3 (**permalink**) 03-22-2009

I have the shore power plugged into the battery charge, yes.

Are you suggesting the following:
1) Leave shore power plugged in
2) While shore power cable is plugged in, kill the breaker for the battery charger, but leave the overall breaker open?

tager · #4 (**permalink**) 03-22-2009

Unplug your boat. Because soon the process of elimination is going to be on stuff more expensive than zincs.

JohnRPollard · #5 (**permalink**) 03-22-2009

Quote:

Originally Posted by night0wl

I have the shore power plugged into the battery charge, yes.

Are you suggesting the following:
1) Leave shore power plugged in
2) While shore power cable is plugged in, kill the breaker for the battery charger, but leave the overall breaker open?

Yes. But make sure you keep a watch on the zincs (see tager's note above).

My hunch is that you are leaking DC and the battery charger is providing an unlimited supply.

However, you should do some additional searching around here on Sailnet. There have been more than a few threads about similar dockside issues. But the above advice about the process of elimination applies regardless.

billyruffn · #6 (**permalink**) 03-22-2009

It's either your boat, or the boats around you that have a problem. Turn off the shore power and shut down everything, and see what happens next with the zincs. If the problem persists in a month or so, it's not you, but those around you in the marina.

Your diver should be careful if there are electrical currents in the water. Micro-currents can kill a swimmer by interupting muscle functions.

PS -- Just re-read the OP. Living aboard presents a problem. This may be hard to diagnose while dependent on shore power. Perhaps you could request another slip and see if the problem persists there. Talk to the marina manager -- have others had this problem? I agree with the above post that more expensive things are in store if you can't keep putting new zincs in service. You might also try one of those sacrificial "fish" zincs as they don't require a diver to replace them. Also, it may be time to get an electician involved -- he'll probably be cheaper than the alternative.

rdstanley · #7 (**permalink**) 03-22-2009

I'd see if the marina would have an electrician check the docks AC just to make sure it's not leaking. Most of the time it's DC current. One thing you may do to ensure it's not your boat leaking DC current is install a galvanic isolator. I'd also make sure the zincs you are using are for the type of water you are in.

One last tip, move the boat away from the docks and other boats when it's time to dive on it. Better safe than sorry and it sounds like you definately have a problem.

Good luck.

JohnRPollard · #8 (**permalink**) 03-22-2009

Funny, when I read the OP I got the impression he was not at a marina, but instead was at his own dock. That's why I did not mention some of the other marina-related possibilities.

Sequitur · #9 (**permalink**) 03-22-2009

Does your shore power come into the boat through an isolation transformer?

night0wl · #10 (**permalink**) 03-22-2009

Quote:

Originally Posted by JohnRPollard

Funny, when I read the OP I got the impression he was not at a marina, but instead was at his own dock. That's why I did not mention some of the other marina-related possibilities.

You are correct - this is my own dock behind my personal home in fort lauderdale...no marina.