Zincs... Why ate up so fast?

[Stillraining]

I re-pulled my boat after only 2 months in the water...All the zincs were a fresh new install at splash two months ago.

The two on the 1 1/8" SS prop shaft are 1/3 gone and the ones on the SS strut assembly are not even touched...I did sand all the contact surfaces to Brite mettle befor installing.

I cant believe the shaft zincs were so far goon so fast while the other two look brand new.

What could I possibly have going on in the boat to do this? One was ate up enough to be loose...

PS: I never leave shore power plugged in..I only plug it in for the couple hours I'm at the boat per week.

[S/V Illusion]

have you checked to see if you have a current draw to ground or any significant voltage to ground?

The is a HUGE volume of info here as well as a myriad of other sites describing the possible causes which are varied and numerous. All you will get are guesses until you identify the source of the leakage, either on you boat or a neighbor's.

[peterroach]

What type of battery charger are you using? Only marine chargers will keep you from eating your zincs

[David M]

Electrolysis like that is generally caused by stray DC currents..not AC. What has changed on your boat since the last haulout? Have you installed something new? Something DC is fully or partially grounding into the water is my best guess.

[Stillraining]

Originally Posted by S/V Illusion

have you checked to see if you have a current draw to ground or any significant voltage to ground?

No I have not..I will next trip to the boat

Originally Posted by peterroach

What type of battery charger are you using? Only marine chargers will keep you from eating your zincs

True Charge 40

Originally Posted by David M

Electrolysis like that is generally caused by stray DC currents..not AC. What has changed on your boat since the last haulout? Have you installed something new? Something DC is fully or partially grounding into the water is my best guess

The boat is new to me I have nothing to gage by.

I did forget to re-hook up all the origional wires to my grounding plate after installing a new one and waiting for the sealant to cure if that matters

[Splash Gordon]

You sound like you've got stray current burning your boat away!
The guru's here posted this a while ago, and I've found it invaluable.
You need to also check that you've got a galvanic isolator in your dock supply, because your shore-power (I assume you've got one) could also be leaking a few mV into the environment and lighting up your boat!


If you have a multimeter on board, you can test your boat and your dock. Get a pencil zinc, drill a hole in it for a wire and solder a length of wire to it. Connect that to theblack lead of your meter, and suspend the zinc in the water, after cleaning it with a Scotchbrite pad. Put the red lead to your bonding system.The meter readings indicate thus with bronze and stainless protected metals:
Reading DC volts on 2 volt scale:
Minimum protection: 500-550mV (0.5V)
Full protection: 430-480mV
Overprotected: less than 380mV

For the posts this was condensed from, look at
http://www.cruisersforum.com/forums/...rina-8445.html

[AnchorageGuy]

All you never wanted to know

electrolysis - Google Search

[svHyLyte]

You may have an internal current leak too your grounding system. We had a similar experience discussed in other threads on this site in the Spring of 2006. It turned out that an improperly secured power cable to our starting battery had chafed through on a grounding strap from our fuel tank allowing current to pass into the grounding system as our battery charger merrily hummed away. We had to replace the prop-shaft and cutlass bearing and have our Gori folding prop reconditioned at enormous cost.

The electrical wizzards here abouts can instruct you on how to check for current drain when you think you've turned everything off but you must also physically check each and every hot lead in your electrical system. Our's was found entirely by accident by a yard worker doing some clean-up (thank goodness!). Now I check for anything loose or unprotected whenever I have occassion to go into the engine and machine spaces for anything, which is at least monthly if not more often.

FWIW...

s/v HyLyte

[CaptHead]

the buttons usually last 3 to 4 months. sounds normal to me.

[Nauticatarcher]

I usually change shaft anode yearly, main anode every 2-3 yrs, problem with shaft anode is after 2-3 months it becomes loose on shaft and rattles so I have to go over side and tighten it, yours doesn't sound that bad, nothing worse than an anode thats not working

[Stillraining]

Originally Posted by Splash Gordon

You sound like you've got stray current burning your boat away!
The guru's here posted this a while ago, and I've found it invaluable.
You need to also check that you've got a galvanic isolator in your dock supply, because your shore-power (I assume you've got one) could also be leaking a few mV into the environment and lighting up your boat!


If you have a multimeter on board, you can test your boat and your dock. Get a pencil zinc, drill a hole in it for a wire and solder a length of wire to it. Connect that to theblack lead of your meter, and suspend the zinc in the water, after cleaning it with a Scotchbrite pad. Put the red lead to your bonding system.The meter readings indicate thus with bronze and stainless protected metals:
Reading DC volts on 2 volt scale:
Minimum protection: 500-550mV (0.5V)
Full protection: 430-480mV
Overprotected: less than 380mV

For the posts this was condensed from, look at
http://www.cruisersforum.com/forums/...rina-8445.html

Thank you... great info on how to do that ..which I only partially observed preformed once before and never understood... I did search this forum before posting the question but nothing came up which I thought was odd.

Originally Posted by Chuck Baier

All you never wanted to know

electrolysis - Google Search

Originally Posted by svHyLyte

You may have an internal current leak too your grounding system. We had a similar experience discussed in other threads on this site in the Spring of 2006. It turned out that an improperly secured power cable to our starting battery had chafed through on a grounding strap from our fuel tank allowing current to pass into the grounding system as our battery charger merrily hummed away. We had to replace the prop-shaft and cutlass bearing and have our Gori folding prop reconditioned at enormous cost.

The electrical wizzards here abouts can instruct you on how to check for current drain when you think you've turned everything off but you must also physically check each and every hot lead in your electrical system. Our's was found entirely by accident by a yard worker doing some clean-up (thank goodness!). Now I check for anything loose or unprotected whenever I have occassion to go into the engine and machine spaces for anything, which is at least monthly if not more often.

FWIW...

s/v HyLyte

Yikes...not looking forward to that level of detection..but will do it...Thanks

Originally Posted by CaptHead

the buttons usually last 3 to 4 months. sounds normal to me.

OK..sounds like I might have to dust off my scuba gear after all thease years...AND loose a bunch of weight to fit in my wet suit....Looks like I've got about 5 or 6 months to get that part done...

Originally Posted by Nauticatarcher

I usually change shaft anode yearly, main anode every 2-3 yrs, problem with shaft anode is after 2-3 months it becomes loose on shaft and rattles so I have to go over side and tighten it, yours doesn't sound that bad, nothing worse than an anode thats not working

Good to know Thanks...Also I did not know about setting them with a hammer when tightening them so Im sure that had a lot to do with them being loose as well. One was so loose it was rattle loose the other one you could twist it with one hand. I just could not believe they were almost half gone in 2 months is all..