"Fish" Zincs

[Ken Krawford]

I've searched the forum and couldn't find this topic.  Does anyone have a reference showing the effectiveness (or lack thereof) for  "fish" type zincs that you hang overboard from a wire connected to your bonding system ?
Thanks.

[Ken Juul]

Aren't you in fresh water?  Curious why you think you need extra zinc protection.

[Ken Heyman]

Are we talking about lightning protection or the usual zinc deterrent to electrolysis?  Also, I don't believe that Catlaina's have any OEM bonding system in the way recommended by the experts i.e. grounding plate and wire from the mast bottom to the keel nor anything tying all metal components together. There is allot on our site regarding lightning protection etc. Just do a search.

Ken

[Ron Hill]

Ken Krawford : The "fish Zn" might help a lightening strike, IF that "900K Volt gorilla" decided to follow that path !

Ken Juel : Not that many years ago, I found that my father had mounted a Zn that screwed into the scag of his CrisCraft.  I said, "Dad you have the boat in fresh water and besides it's a wooden boat that the Zn is screwed into". 
The answer was quite simple - when you're 86 years old you can do what ever you please!!!   A thought

[Ken Krawford]

Yes I am in fresh water but had this discussion with someone who has a boat in salt.  The concern was electrolysis, not lightning.  Wouldn't the wire need to end up somewhere on the engine block to be effective?

[Stu Jackson]

Ken, it's simply not necessary.  The ONLY galvanic corrosion issue is dealt with by the zinc in the HX.

[pablosgirl]

Stu,  I disagree.  The zinc in the HX may take care of the galvanic corrosion for the HX but it will not effectively take care of the propeller or shaft in salt water.  The PO has put a rubber gasket between the HX and its brackets.  Also, fresh water galvanic corrosion can take place, if the boat is connected to shore power all the time and another boat in the marina has a leaking ground to the water (there is always some salt present, even in fresh water).  Here on the gulf coast I have found that I can extend the time between the replacement of the 2 collar zincs that I keep on my bronze prop shaft by using a "fish" zinc.  Before using the "fish" I was lucky to get 6 months out of the zincs.  After the fish, I replace them at 12 month intervals.  I have a 10 gage wire connected to the ground bolt on the engine block lead to the aft cockpit locker where I have a large spade connector that attaches to the "fish" wire.  This provides a quick disconnect to speed up departure time from the dock.  The "fish" wire is tied to the aft mooring cleat on the dock and stays there all the time.  I just disconnect the "fish" wire and throw it on the dock when departing the slip.

[Stu Jackson]

Just another reason to not keep the boat plugged in all the time.

I have a rubber tire hose between the HX and the bracket, but I also have hose clamps that connect the HX to the bracket.  Isolation? Not!

Glad it works for you.

[Ken Juul]

My boat is in brackish water, so boats in saltier water may go through more zincs, but I only use one shaft zinc a year.  Even then it appears to be less than half gone.  Be interested to hear if 2 zincs every 6 months is normal.  If not, you may have a problem you didn't realize.

[Bill Asbury]

My previous C34 was in brackish water at our homeowners association marina and I discovered evidence of galvanic corrosion on my Max-Prop ($$$) a year or two ago, apparently from stray current from another boat or boats, at which time I may have been plugged in to shore a lot, so I bought and used a large fish zinc attached to the engine block until I could get a galvanic isolator installed, after which I didn't need to use the fish zinc any longer.  Since then I've become a convert to being unplugged most of the time, thanks to the guidance of Ron and Stu et al.   Still have the fish zinc on standby if needed with new to me this past week 2005 C34 with fixed three-blade prop.
Bill

[Ron Hill]

Ken : I agree with Ted - what is your fish Zn trying to protect?  In the discussion, I've gotton lost!!

[dave davis]

I don't like sending my prop off to get it cleaned up and smooth down the pitting every 4-6 years. Ever since I added a large 4/6 inch zinc I have not needed to have this done(as often). It's pretty simple to connect the zinc with a copper wire and ground it to the engine block. WM zinc cost $20. It just hangs there about prop high and I pull it aboard when I am out sailing. I also have an isolator on the green wire from the ground. All this was recommend by the Harbor electrical guru. Ron would call this a case of weiring a belt with suspenders.
Dave-707-SF

[Ron Hill]

Dave : I agree with you on what your "fish Zn" protects.

What I was asking Ken about, is what does he want HIS fish Zn to protect???

[Ken Krawford]

Ron, the idea for the zinc was to supplement the protection from electrolysis.