What does the zinc protect - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 19 Old 06-02-2008 Thread Starter
Senior Member
 
davidpm's Avatar
 
Join Date: Oct 2007
Location: Madison
Posts: 4,043
Thanks: 273
Thanked 62 Times in 53 Posts
Rep Power: 8
 
What does the zinc protect

We just replaced the pencil zinc in a Universal M25 Cat 30 that we just started working on.
The zinc was completly gone. No way of telling when it was replaced last. What damange should we be looking for?
The water injector fitting in the wet exhaust fell off. Is this collateral damage from the zinc? What else.
davidpm is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 19 Old 06-02-2008
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,887
Thanks: 20
Thanked 222 Times in 169 Posts
Rep Power: 16
       
Ahhh...

Quote:
Originally Posted by davidpm View Post
What does the zinc protect
Your wallet!!! Do NOT let them disapear!! Check and change often..

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Maine Sail is offline  
Quote Quick Reply Share with Facebook
post #3 of 19 Old 06-02-2008
Member
 
xtatico1404's Avatar
 
Join Date: Jan 2008
Posts: 64
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
 
what does the zinc protect?......pretty much the metal to which it is attached. Zinc "sacrifices" itself in order to prevent corrosion on the metal that it is contact with, usually steel or stainless steel, so as Halekai said, check them often and change them when needed.

here is a good informational link
ElectroGuard | Manufacturing Top Quality Zinc Anodes Since 1940

1982 Gib'Sea 105

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
xtatico1404 is offline  
Quote Quick Reply Share with Facebook
post #4 of 19 Old 06-02-2008
Sea Slacker
 
Join Date: Jan 2007
Posts: 1,789
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
Ugh. I am still waiting for a diver (or, barring that, short haul). I dread to think what can be there - the zinc is nearing a year old, all in the water.

Seriously though - whats the expected lifetime of underwater zinc on the propeller?
brak is offline  
Quote Quick Reply Share with Facebook
post #5 of 19 Old 06-02-2008
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,887
Thanks: 20
Thanked 222 Times in 169 Posts
Rep Power: 16
       
Quote:
Originally Posted by brak View Post
Ugh. I am still waiting for a diver (or, barring that, short haul). I dread to think what can be there - the zinc is nearing a year old, all in the water.

Seriously though - whats the expected lifetime of underwater zinc on the propeller?
it totally depends of your situation. I am on a mooring and could get three seasons out of my prop zincs because I have almost zero stray current and I am not plugged into shore power.

Every marina is different and I've been in marinas where zincs last three weeks!! The diver was driving a Mercedes..

There is NOT one answer to how long a zinc will last as every situation is different!

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Maine Sail is offline  
Quote Quick Reply Share with Facebook
post #6 of 19 Old 06-02-2008
Grasshopper
 
JiffyLube's Avatar
 
Join Date: Jan 2008
Location: Oceanside, Ca.
Posts: 896
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
 
The question as to how often zincs were replaced was asked at one of our Power Squadron meetings, and almost everyone said their zincs needed to changed at about 3 months. 3 months seemed to be how long it took to erode the zincs to 50% in the salt water in our marinas, and 50% is when they should be changed. In my case I have an isolator installed, and my zincs are at 50% at around 5 to 6 months.
JiffyLube is offline  
Quote Quick Reply Share with Facebook
post #7 of 19 Old 06-02-2008
Sea Slacker
 
Join Date: Jan 2007
Posts: 1,789
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
Do you keep the boat connected to shore power? I don't - I wonder if this helps with this. Well, anyway - I hope to find out next week, if the diver gets about. If not - in 2 weeks or so, have noone to help me get the boat out of the slip until then

Quote:
Originally Posted by JiffyLube View Post
The question as to how often zincs were replaced was asked at one of our Power Squadron meetings, and almost everyone said their zincs needed to changed at about 3 months. 3 months seemed to be how long it took to erode the zincs to 50% in the salt water in our marinas, and 50% is when they should be changed. In my case I have an isolator installed, and my zincs are at 50% at around 5 to 6 months.
brak is offline  
Quote Quick Reply Share with Facebook
post #8 of 19 Old 06-02-2008
Wannabe Sailing Bum
 
Vitesse473's Avatar
 
Join Date: Mar 2008
Location: SF Bay Area
Posts: 142
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
 
electrolysis is a very tricky subject. A lot depends on how many metal thru-hull fittings were built into your boat, and how well your electrical system is maintained. You could be dumping energy into the water that is eating your own zincs. If you have many thru-hull fittings, make sure you are properly terminating all of them to where your zinc is located. Then, turn to understanding the boats around you. You likely have a boat or two next to your slip that is pumping energy into the water. Unless you (or a good harbor master) tests for leakage at every slip, you'll never know for sure.

In any case, if your zinc is completely gone, look for pitting on the prop and any other underwater metal surfaces. That's a clear sign your zincs are failing to protect the underwater metals.
Vitesse473 is offline  
Quote Quick Reply Share with Facebook
post #9 of 19 Old 06-02-2008
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 15 Times in 12 Posts
Rep Power: 14
         
Chances are good that the pencil zinc was probably protecting the heat exchanger for the cooling system. If it was missing for long, it is a bad thing... check it often, and replace when it gets down to about half it's original size.

Quote:
Originally Posted by davidpm View Post
We just replaced the pencil zinc in a Universal M25 Cat 30 that we just started working on.
The zinc was completly gone. No way of telling when it was replaced last. What damange should we be looking for?
The water injector fitting in the wet exhaust fell off. Is this collateral damage from the zinc? What else.

Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #10 of 19 Old 06-03-2008
Senior Member
 
Join Date: Sep 2006
Location: Scotland
Posts: 2,364
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 9
 
Think of those "hang over the side" style zincs, often shaped like fish. They are hung over the gunwhale and dipped in the drink. The other end is coupled electrically to your prop shaft, or motor, or whatever, and when the zinc slowly fizzes off, it will tend to hold the protected component negative relative to the zinc. Being negative will radically slow the corrosion reaction... that thrives on being positive.
When the zinc fizzes off ("sacrificial anode") you get another one.
It does not protect when you are on the move, as you have to lift the fish out, but most of us are stopped, most of the time.

In fresh water, some outboards use magnesium sacrificial anodes, as zinc cannot quite get enough sacrificing going (it is not as reactive as magnesium) but I don't think that you need them. Fresh water is FAR more forgiving to metals. Often they don't need any protection at all when in fresh water.
Rockter is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Zinc to protect bronze parts? brak Gear & Maintenance 3 05-27-2008 11:14 AM
Shaft Zinc FlySwat Gear & Maintenance 6 06-11-2005 04:15 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome