Dissimilar metals

[Kimbrey]

Hello again,
We're still looking and researching Airstream or at least I am. The wife as some cold feet right at the minute but that's understandable with some of her medical concerns. Personally I'm leaning toward a 30' Classic as it looks to have the most comfortable seating.

Anyway I research the Gee Whiz out of things before making any sort of move. I have a question regarding Airstreams since they are aluminum. My previous sport fishing boat a 26' Duckworth Offshore was aluminum. You had to be very cautious with dissimilar metals creating corrosion. IE a stainless screw or bolt making contact with the aluminum created a reaction with corrosion being the result. We had to be cautious that the screws/bolts were gasketed and or the threads coated with TefGel and I still fought corrosion. It was enough of a concern that I sold the boat and went back to fibreglass.

Do you Airstream owners see any corrosion et cetera with the trailers in areas where dissimilar metals are used? Or is Airstreams aluminum coated somehow to prevent this to a certain extent? Or maybe the difference between the trailers and a boat is salt water? Not sure about that. Anyway the whole dissimilar metal thing is ingrained in my head so it has me wondering about these trailers.

[DMT]

Stand by for the tsunami of filiform replies🥴.

[Wayne&Sam]

Yes, dissimilar metals can be a problem, but stainless steel and aluminum are not one of them. My understanding is that is the combination you want to use.

[Jcondon]

Stainless steel and aluminum are fairly reactive to each other and the aluminum suffers greatly. Just like on your boat anodes you should be using hot dipped galvanized hardware. It is relatively neutral to aluminum. Tonight I was getting my stainless crab pots ready for the season. We use aluminum anodes on these and in one year the aluminum is gone. 2.5 pounds. Avoid stainless unless it will stay perfectly dry. All galvanic action needs an electrolyte.

[Kimbrey]

Originally Posted by Wayne&Sam

Yes, dissimilar metals can be a problem, but stainless steel and aluminum are not one of them. My understanding is that is the combination you want to use.

I'm fairly certain that's wrong or at least it is on boats. A stainless fastener into aluminum without being isolated will corrode the aluminum. A heater exhaust vent was installed with stainless screws on my boat. Paint was bubbling around it after a couple of years. Just coating the screws with TefGel probably would have prevented that. It's goopy/sticky stuff.

Anyway I'm just wondering/researching and learning. Just gotta get the wife moving.

[ROBERT CROSS]

Originally Posted by DMT

Stand by for the tsunami of filiform replies🥴.

Filiform is NOT galvanic corrosion.
Galvanic needs water, AS's don't float.

Very good info here.


I replaced all base metal fasteners with stainless on both our AS's, 35yrs sfsg.

Salt Sea air is NOT AS friendly, a good maint procedure is required.

Bob
🇺🇸

[Jcondon]

Looking at your chart it appears that galvanized steel is least reactive to aluminum and stainless steel is almost the most reactive? Who would have thought?

[Belegedhel]

Originally Posted by Kimbrey

Hello again,
Do you Airstream owners see any corrosion et cetera with the trailers in areas where dissimilar metals are used? Or is Airstreams aluminum coated somehow to prevent this to a certain extent? Or maybe the difference between the trailers and a boat is salt water? Not sure about that. Anyway the whole dissimilar metal thing is ingrained in my head so it has me wondering about these trailers.

Well, to answer the original question, yes dissimilar metals can cause corrosion in Airstreams (SS fasteners really should be avoided unless thoroughly sealed, etc., as counter-intuitive as that seems). I suppose the difference between trailers and boats is that the trailers are not wet most the time, the water is relatively fresh (even distilled in the case of rain water), and therefore not as conducive to ionic transfer. SS fasteners, if used are generally thoroughly gooped, just to avoid creating a leak.

The newer trailers do have a factory applied plasti-coat on the aluminum which protects it to some extent, but even the vintage trailers that have been around for decades, have had the clearcoat polished off, and have had various modifications made to them (possibly with stainless screws) rarely have existentially threatening corrosion.

If you want something to worry about, consider that the skin on a trailer is .03-.04" thick, whereas the hull on your aluminum boat is...well... a lot thicker. Bumping your aluminum boat into a dock results in no damage, bumping your Airstream into a low hanging branch could result in a crumpled segment and thousands of dollars in repairs.

good luck!