Aluminum boat trailer with SS hardware in saltwater

[Donald]

Getting ready to order a boat trailer. A dealer suggested against SS hardware because of galvanic corrosion in saltwater. I don't know one way or the other. The trailer goes into saltwater but does not stay in saltwater.

I watched a YouTube of a Volvo Penta marine engine with aluminum exhaust manifold and they suggested not to use a SS elbow but rather a cast iron elbow. Same reason, galvanic corrosion. But this is a situation where the saltwater would be continuous.

I am up in the air. There is galvanized steel on the trailer, only the frame is aluminum. It's about $250 extra

 

[MParr]

What to Look for in a Boat Trailer | Sport Fishing Mag

10 things to consider when buying a boat trailer

www.sportfishingmag.com

 

[Donald]

What to Look for in a Boat Trailer | Sport Fishing Mag

10 things to consider when buying a boat trailer

www.sportfishingmag.com

Unfortunately it does not talk about SS hardware and galvanic corrosion.

 

[philipp10]

A quick Google search says to NOT mix stainless steel and aluminum. Since the option to do this costs more and the dealer is trying to talk you out of it....clearly he is not trying to upsell you.

 

[stockrex]

yes, it would be exposed to galvanic corrosion
no experience in salt water but lots of experience in MI salt.

call of the big boat dealers in AL or FL or MS, talk to service dept.

you can put a coat of Marine grease in the mating surfaces and do it often to prevent the corro.

 

[eljefino]

Some flavors of SS have threads that gall themselves quite well even without an electrolyte.

If I were concerned, I'd blow the factory hardware apart annually and slather it with anti-sieze. But at some point you get diminishing returns for your efforts.

 

[tom slick]

If you refer to a galvanic chart the closer the materials are on the chart the less galvanic difference which means less corrosion potential. Al steel are much closer than and Al and 300/400 SS.

Galvanic series

 

[doitmyself]

Donald, we just had a pretty informative discussion a few days ago here: https://www.bobistheoilguy.com/forums/threads/aluminum-galvanized-steel-galvanic-corrosion.331757/

One new thing I learned is that it seems that if you have a very large anode (active/corroded) like aluminum and just a tiny cathode (passive/protected) like stainless steel, it might not be a problem. It also seems that zinc or galvanized steel is ok with aluminum.

This maybe explains why my greenhouse cooling pad systems (water, aluminum, stainless bolts) don't have any galvanic corrosion in over 20 years. Or, why the aluminum porch railing I studied last year o.k.ed the use of stainless anchor bolts?

tom slick, your chart is interesting in that it lists many stainless types as "active" vs. "passive".

 

[tom slick]

Article: When is stainless steel passive or active - formation of the passive layer

Active is when the chromium oxide layer is stripped. That’s why SS is “passivated” after fabrication is done. Salt water (or anything with chlorides) strips the passive layer and exposure to oxygen replaces it. Aluminum does a similar process forming aluminum oxide (anodizing)

 

[2strokeNorthstar]

Been taking boats and trailers in the salt for about 20 years. SS hardware isn’t a worry. The leaf springs, lug nuts, hubs, axles will rust first. The best thing you can do is wash it off with a power washer or salt away etc. Out of a garden hose. Look at Marine motors plenty of aluminum and stainless mixed.

 

[4WD]

Been taking boats and trailers in the salt for about 20 years. SS hardware isn’t a worry. The leaf springs, lug nuts, hubs, axles will rust first. The best thing you can do is wash it off with a power washer or salt away etc. Out of a garden hose. Look at Marine motors plenty of aluminum and stainless mixed.

Same … Rinse, rinse, and rinse … and I have had both aluminum and galvanized steel. The SST hardware was never an issue but spring steel needs lots of attention … my hubs are coated and I use Ospho as needed …

 

[1978elcamino]

YOU WANT STAINLESS

I have a boat trailer which has stainless hardware except for the bolts that were hidden under the carpet that hold down the bunks. Those have been the ONLY fasteners I had replaced since it was built in 2004. Everything else is still perfect. The boat is used only in salt water.