galvanic corrosion

[zeeprogrammer]

Some time ago I had a wild hair about building a sailing ship out of metal.
That is, for example, bulkheads of aluminum and planking of brass.

Some of the responses mentioned 'galvanic corrosion' and 'dissimilar metals'.
That wild hair returned a bit today and I did some googling about corrosion.

As I understand it, a 3rd element is needed, an electrolyte. So putting such a ship in the sea would be a big problem.

It makes me wonder about the various models people make and if such corrosion is something they think about.

I also read that anodizing the aluminum could help.
But is this something to worry about (for the next 40 years) if the model (i.e. ship) never touches water?
Or, if it's fresh water, whether a good rinsing works.

In any case, I'd be interested in seeing what anyone would have to say about this process.

Thanks.

[Ian S C]

Zee, the only thing I can think of, if theboat never touches water it may suffer corrosion if it is stored in a place with high humidity.  Even fresh water would cause some corrosion, as there is always some contaminents to form an electrolite. After washing out, it would need a good drying.
Ian S C

[steamer]

The Herreshoffs built the "Ranger" for the America's cup defense with bronze plating below the water line steel above the water line and aluminum decking on steel frames   the boat won but was scrapped the same year.   Combine all of the above with a massive lead keel and that must have been a wondrous galvanic cell.

On edit I have the boat name wrong    but I'll find it...
Dave

[crueby]

The Herreshoffs built the "Ranger" for the America's cup defense with bronze plating below the water line steel above the water line and aluminum decking on steel frames   the boat won but was scrapped the same year.   Combine all of the above with a massive lead keel and that must have been a wondrous galvanic cell.

On edit I have the boat name wrong    but I'll find it...
Dave

That was the Defender. It was not broken up the same year, it sat for 4 years before being rebuilt in 1899, then was broken up in 1901.

[joe d]

On edit I have the boat name wrong    but I'll find it...

Was the Defender I think?

Cheers, Joe

[joe d]

Chris:  You type faster than me!
Joe

[steamer]

Thanks Chris!

Dave

[b.lindsey]

Zee, its hard to imagine this being a huge problem for a static model that may never see the water. While it may well depend on how you were planning to attach the brass planking to the aluminum bulkheads (screws vs. glue), you might consider some sort of very thin insulating material between the dis-similar metals as added insurance.

Bill

[crueby]

Zee, its hard to imagine this being a huge problem for a static model that may never see the water. While it may well depend on how you were planning to attach the brass planking to the aluminum bulkheads (screws vs. glue), you might consider some sort of very thin insulating material between the dis-similar metals as added insurance.

Bill

If it was to be used in the water, it would not matter much if there was insulating material between the different metals, the water would span the gaps. For water use, it would be important to add sacrificial zinc plates to the hull, like they do on full size boats to keep bronze props/etc from being eaten away by the galvanic action. The zincs 'rot' away quicker, saving the 'good' metals.
For static display, its not much of a problem - look at how many of our models are mixes of metals, and they are not swiss cheesed by the galvanic action.