Aluminum Anodes

[Once and Future]

Aluminum anodes have come up in the talk about boat stray voltages.

Anybody care to give the theory as to when you would use an aluminum anode instead of a zinc one?

[Lulu]

Al anodes have been around for a long time. They've been used primarily used on steel vessels operating in fresh water. Within the last 10 or so years, tug boats have used them to quite down the environmentalist claim that zinc poisons the water. There are forces trying to push legislation to eliminate the use of zincs on boats in CA.

In respect to the use of Al and zinc on salmon trollers and tuna boats, the addition of Al to the zinc pattern is an attempt to increase the hull potential and add ions into the water behind the boat. The theory is; "more charged particles (ions) and a high hull potential attracts top predators (like salmon and tuna) to a boat."

You wouldn't use Al instead of zinc. You would use Al in addition to your normal zinc load.

[Once and Future]

Thanks for the reply!

[Salty]

I use 4. I still never catch. Change em every 6 months.

[Lulu]

Salty, I was scrubbing the Al anodes once a month during the season. What I learned was they burn up and are no longer active. This year I'm going to try replacing them when the white scale builds up. I'll let you know what happens.

[Trnaround]

Lulu thank you for the clear explanations of electrical theory in your former posts, very helpful. I posted this link in a thread about stainless steel, but thought I would drop it in here because the Galvanic chart shows how anodic dissimilar metals are. Note there are differences in the types of aluminum and also zinc is an anode to aluminum if they are in the same area. http://www.estainlesssteel.com/corrosion.shtml
Good fishing.

[Lulu]

Turnaround, this was very interesting link. I didn't know mechanical scrubbing destroys the protective surface of stainless. I'll take preventative measures to keep the SS protected. As a note, I've noticed that rubbing Never Cease on a SS plate will take the rust off and make it shine. Now I know why. Thank you