Zinc overboard!

[Borax Johnson 107]

So, if I really want to be anal, and want to put a zinc over the side when I am tied up, do I attach it to....

the leads to the ~6x8" zinc that is mounted near the aft port quarter via 2 3/8" bolts, or attached to the engine. It seems that clipped on to the big zinc is the place, I just wanted to be sure.

[Zonker 5,248]

As long as you have a good path to the underwater metals you are connecting it don't matter (measure the resistance of the various paths and see if all your bonding wires are making a good connection. You'll need a long wire for your multimeter though.

 

Ranting Hat on:

(I'm a strong believer on plastic boats to ISOLATE many underwater metals and locally protect those that need it.

i.e. bronze or marelon thru hulls don't get bonded to nothing. They won't corrode if left alone.

s.s. prop shafts get their own zinc
bronze fixed props do not get a zinc

feathering props get a zinc if the manufacturer says so (usually dis-similar metals like gears and blades)

saildrive legs get a zinc where the manufacturer says so.

That usually only leaves a s.s. rudder shaft which is minimally exposed. Most of them go through life for decades with no zinc but if you want to connect an internal wire to the shaft inside the boat, to an external zinc I'm ok with that. The bigger risk with s.s. shafts is crevice corrosion in the bearing or water getting into the blade and oxygen starved environments.

 

 

[Borax Johnson 107]

Thanks for the hat, mad hatter!

I have bronze thru hulls, check.

SS prop shaft with a Gori 3 blade and zinc on shaft (because Gori had to be rebuilt when the PO's zinc ran out.

I also have that big ass zinc. I was thinking a cable from that overboard to a zinc or (aluminum/magnesium anode) for fresh/saltwater. Seems cheaper than a diver to check & replace, no?

[jamhass 134]

I used an overboard zinc (an old hull zinc) when in a marina, mainly as a tell-tale.  If there is a hot boat nearby, the overboard zinc shows erosion as a warning.  I mounted a bronze screw out of the way in a cockpit cubby and wired it to a good ground, and I clip the zinc to that.  This system has alerted me to nearby electrical issues, more than once resulting in moving to slips farther away from the offenders. 

[Zonker 5,248]

That's a good idea. 

[longy 855]

Portable zincs were quite a thing back when aluminum boats were just starting to be built. Often 2 -4 of them around the boat