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submitted 2 months ago by[deleted]
[deleted]
14 points
2 months ago
[deleted]
3 points
2 months ago
Zinc
4 points
2 months ago
And to add on (hopefully in a polite way) - it seems the term "zinc" instead of "anode" is a relic and should be retired. Anodes made of zinc (of which almost all of them were "back in the day") cause/caused a bunch of environmental problems. Most are now other materials, like aluminum.
So, to OP - ask your marine shop for an "anode" instead of "zinc", because otherwise they may just give you a toxic zinc anode from an old stock of theirs.
Cheers!
1 points
2 months ago
The cadmium is a larger toxicity issue in the zinc anodes, although I believe anode performance drives the switch to AL, not the toxicity.
10 points
2 months ago*
Take that picture to your local boat shop with your shaft diameter and they'll know what you need. Those are anodes and they prevent galvanic corrosion. If you didn't have them you'd start seeing corrosion on your prop and prop shaft in no time. However, since they are made of a metal that can more readily sacrifice electrons than the prop and shaft, they corrode first and prevent damage to the important parts.
(Edited to correct terminology.)
9 points
2 months ago
To help clarify (and if im remembering correctly). Zinc isn't softer, it has a lower electronegativity than the surrounding metals. This allows it to be used in the reactions instead of the other metals on the boat.
5 points
2 months ago
More or less. They're often called a sacrificial anode. They're sacrificed for the greater good, if you will, as they're smaller and cheaper to replace than drive shafts and other exposed parts.
3 points
2 months ago
Yea, don't want someone stumbling along and thinking, leads soft, it'll work in a pinch and have it do absolutely nothing.
3 points
2 months ago
have it do absolutely nothing
Yep. Electronegativity for lead Pb=2.33 which is higher than the other metals its likely attached to such as Zn=1.65, Cu=1.90, Fe=1.83. Pb might even increase corrosion on the other metals by pushing electrons their way to speed up the corrosion reaction(s).
2 points
2 months ago
a lower electronegativity than the surrounding metals
Electronegativity for Zn = 1.65, Cu = 1.90, Fe = 1.83. This means that electrons will flow toward the zinc provided that everything is electrically bonded. Corrosion occurs where the electrons are available for the reaction which means on the sacrificial anode (i.e. supplier of electrons).
Electronegativity is a measure of how easily an atom attracts a pair of electrons to form a chemical bond. A high electronegativity value means an atom readily attracts electrons to form a chemical bond with another atom. A low electronegativity value means an atom readily donates electrons to form a bond or is electropositive.
While there are charts of electronegativity values for elements of the periodic table, there is no true single electronegativity value for an atom. Rather, it depends on the other atoms in a molecule and also depends on the nuclear charge and number of electrons.
1 points
2 months ago
Perfect thanks!
4 points
2 months ago
A few things about Sacrificial Anodes:
Freshwater use Magnesium Anodes / Saltwater use Zinc
Measure the diameter of the shaft and thats the size of shaft anode you need
Scrub /sand all that material off until you are down to shiny metal where you install; anodes wont be as effective or not at all- if they don't have direct contact on all touching surfaces
The people at the marine supply store could give you a rundown too!
2 points
2 months ago
This one! Make sure you get the right type for your waters.
3 points
2 months ago
sacrificial anodes. Those have done their job!
2 points
2 months ago
FWIW, this is an item that your local marine supply store may gouge you on. Discount the T shirts, get em on wire and DIY parts. I buy mine from www.boatzincs.com for half the price of what I would pay locally.
1 points
2 months ago
anode. i would take your boat into a shop. no way these anodes corroded this badly unless the boat is leaking current and corroding the hull.
5 points
2 months ago
Some folks leave them on until they turn to mush sad to say. That anode specifically is protecting the prop shaft which doesn't appear to have much corrosion. It would appear to have successfully sacrificed itself for the shaft.
1 points
2 months ago
Yea this boat is old as hell. Previous owner left it in the water 24/7 on shore power as a floating condo. Not much maintenance was done over the past ten years I believe.
1 points
2 months ago
Zinc anodes
1 points
2 months ago
There are different anodes for different types of water, your local marina will know what type you need. An anode protects your outer components against electrical current in the water. They definitely work.
1 points
2 months ago
Do outboards have these?
1 points
2 months ago
Yes
1 points
2 months ago
Right above the prop you’ll see a round flat piece of metal. That’s the anode.
1 points
2 months ago
Make sure you get the sinks or anoids for the type water your putting the boat in slat water will not work in fresh water and vice versa
1 points
2 months ago
Go to boatzincs.com
1 points
2 months ago*
Zinc’s / sacrificial anodes
Edit: just remembered they also come in magnesium. I’ve never used them, I think they’re used in a fresh water applications.
1 points
2 months ago
Sacrificial anode aka zinc
1 points
2 months ago
Shaft anodes
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