Mil-Spec Zinc and Mil-Spec Aluminum anodes provide excellent corrosion protection for steel and aluminum hull vessels that operate in salt or brackish water. Both are very effective. Historically, zinc anodes have been less expensive than aluminum but since 2005 that's no longer the case. The more active, longer lasting aluminum anodes are now less expensive, making them a clear favorite for most commercial applications.
The difference between zinc and aluminum anodes is summarized below:
| Zinc MIL-A-18001K |
Aluminum
Mil-A-24779 (SH) |
|
| Voltage (1) | -1040 mV | -1100 mV |
| Density | 0.258 lbs per cubic-inch | 0.105 lbs per cubic-inch |
| Energy Capacity | 368 amp-hours per lb | 1150 amp-hours per lb |
| Service Life (relative to Zinc) | 100% | 120% |
| Cost (relative to Zinc) | 100% | 75% |
(1) Galvanic voltage produced relative to a silver/silver-chloride electrode in seawater. |
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