very worrying anode problem!

eianm

.
Jul 7, 2010
517
Hunter 42 Sydney
I have been chasing a problem in my Hunter 42 for months. I used to get 14>18 months out of a set of anodes, recently I am completely dissolving anodes in 3 months! I am in a pen , connected to shore power. I had all ground wires replaced, had a new galvanic isolator fitted but still have the problem. Strange thing is , I am losing shaft and skeg anodes but NOT the anode on my Variprop!
I had the local marine elec run tests with a silver/silver anode with shore power connected and disconnected and all readings were well within range- any informed thoughts will be appreciated
 
Oct 19, 2017
7,732
O'Day 19 Littleton, NH
I am in a pen , connected to shore power. I had all ground wires replaced, had a new galvanic isolator fitted but still have the problem. Strange thing is , I am losing shaft and skeg anodes but NOT the anode on my Variprop!
Is this location new? By pen, you mean closed off from open water? What's the water like? Polluted water can increase the rate of corrosion by changing the oxygen level, the Ph or the quality of its electrolytic properties.

Do you have separate grounds for your DC and AC systems? What have you installed that required rewiring, even if it was to disconnect and reconnect your ground? New batteries, changed out or added metal plumbing, installed a lightning rod, new radio or antenna? Have you changed your prop to a different material?

There are dozens of places where a stray current can be inadvertently shunted to your grounding plate, or otherwise leaked to your system. Maybe, if you haven't measured anything wrong, it's connected to some automated cycle like a bilge pump, that only comes on occasionally.

-Will (Dragonfly)
 
Jan 19, 2010
1,169
Catalina 34 Casco Bay
What has changed? Looking back to when you had the 14 to 18 months of anode life, have there been new neighbors? Done any major electronic work? Do you have access to a galvanometer ?
 

eianm

.
Jul 7, 2010
517
Hunter 42 Sydney
thats just it- been in the same marina pen/berth for 10 years and no major electrical work done- thats what is so very confusing!
 
Jan 19, 2010
1,169
Catalina 34 Casco Bay
thats just it- been in the same marina pen/berth for 10 years and no major electrical work done- thats what is so very confusing!
How about the piles? Are the wooden or metal ?
 
Oct 19, 2017
7,732
O'Day 19 Littleton, NH
In ten years, you may have chafe or minor internal corrosion that has led to a minor short. Are you getting more water in your bilge than you use to? Small Leaks could create conductive pathways. If your tests were done after you did a cleanup, your bilge dry, engine grit cleaned off, battery terminals tightened, maybe your leaking current was temporarily stopped when you tested.

-Will (Dragonfly)
 
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
I had the local marine elec run tests with a silver/silver anode with shore power connected and disconnected and all readings were well within range-
Get his "normal readings" in millivolts and post them. They should but close to -0.950 millivolts. Volts

Here is a guess if there are other boats nearby and hooked to shore power too.

Other boats may not be on the same "power use" schedule as your Marine elec.:huh:
Jim...
 
Last edited:
Oct 19, 2017
7,732
O'Day 19 Littleton, NH
How about current present when everything is off? Can you account for all voltages? Is your charger working harder than it should? Is there a shore power draw that can't be accounted for?

You've been in the same slip for ten years with no MAJOR electrical work. How long ago did you first notice the change? What minor work was done around that time? Has the marina done electrical work, dock work, etc?
-Will (Dragonfly)