anodes

I'm building a big steel ship/boat 72' landing craft. I am totally ignorant regarding anodes. Please help.

Ryland

 

Ryland,

Best speak with these chaps. They know their onions when it comes to anodes etc:
http://www.mgduff.co.uk/

 

Or use the forum search function for "zinc electrodes".

 

Don't you have to build steel ships facing North?

Zinc electrodes CDK? I am certain you meen anodes

 

Magnesium for fresh water.....

Put a pair either side of the stern gear, done...

 

He said he was building a big steel ship. I would think that would be sea water and two iether side of stern gear is no where near enough.

You can include your one each side of stern gear and 2 more on the rudder --s and then one 1/2 kilo zinc every 10 feet down each side of the hull.


At least.

 

We have huge bodies of fresh and brackish water over here. Ocean going ships can go 2000 miles inland.

 

No Frosty, I cautiously use the word electrodes because they are in fact cathodes (negative). The industry speaks of "cathodic protection" but somehow in the boating jargon everybody calls them anodes. Both are of course electrodes.

 

Yes, anodes and cathodes are electrodes.
http://en.wikipedia.org/wiki/Electrode

 

Machinery and heat exchangers also need protection; particularly if they are insulated with rubber hose connections. They use "pencil anodes" which look like water plugs but have a zinc, aluminum or magnesium bar attached to the inside.
The anode is the sacrificial part of the system, so the zincs are anodes.
http://electrochem.cwru.edu/encycl/art-e01-electroplat.htm
http://en.wikipedia.org/wiki/Electroplating

 

Im sorry I did think that.

 

Urrm what?

http://en.wikipedia.org/wiki/Galvanic_corrosion

 

One must be a bit careful here- An anode casts off electrons and a cathode gathers them in. Although a steel hull is negatively biased, it is still the cathode. The hull's connection to the zinc drives this. The cessation of oxidation on the hull lowers the voltage on the hull even more. Follow the electrons, not the voltage.

 

Okay, so I did a little more research, spurred by an exchange of PMs with CDK.
I found this under wiki cathode-

What seems to have happened is that the anode and cathode were defined for a battery based on charging of the battery. When discharging, the roles are reversed, but we don't change the names. A galvanic cell is always in discharge mode, it seems. At any rate, the usage is standardized.

 

Cool, you guys are a wealth of knowledge.

Check out Zingard, cover the hull in zinc.

http://www.mgduff.co.uk/zingard.html