marine-grade aluminum

6061 and 5052 have been the most common grades used in building commercial and custom boats -- 6061 for structure and 5052 for skins. There is some use of 1100 in non-structural applications. And Alclad (alloy aluminum with rolled-on layers of 1100, for corrosion resistance) is used in a few applications.

They aren't the best for any specific purpose, but they combine weldability and medium strength (except for 1100, which is weak) with reasonable corrosion resistance. 1100 has the best corrosion resistance. For all practical purposes, it's pure aluminum.

Ed Huntress

Aircraft aluminium that got wet? Gerry :-)} London, Canada

Usually 5052 (Ductile) or 6061(Strong but more brittle) alloys are used for boats (and airplanes) operating in saltwater environments. - Graham, Vancouver Canada

Hey, you can be silly but I moved from MN to CA 13 years ago and live about 5 blocks from the ocean and found that the aluminum on my 650 Honda and my bike soon lost it's shine and later started decaying into a white powder. Several years ago I went on a trip to Hawaii and at a place called "the blowhole". the big tourist attraction there was not the hole but an adbandoned Cadillac which all of it's aluminum parts had decayed to powder. Is it like Ed says that pure al is more resistant to water based corrosion or are there more corrosion resistant alloys? Engineman1 Engineman1

1100 aluminum is near pure and is often used for decorative panels and tanks for chemicals. It is extremely non-reactive. Most shiny diamondplate is Al-Clad, meaning it has a layer of pure aluminum plated over it so it stays shiny longer. 1100 aluminum is extremely soft, so it is never used where strength is needed.

Aircraft grades of aluminm would be 2024, 7075, and 6061. Marine grades are 5052, 5086, 5083, and 6061 for stuff above the waterline like the cabins and internal structure.

5052 is used for the majofity of hulls, with 5086 as the keel, and strength ribs.

Pure aluminum is very resistant. I think that the fancier the alloy the more corrosion prone it gets. I remember back in the '60s some C130s were "enhanced" with super high tech alloy spars that started turning to powder within a few months. Robins AFB spent several years rebuilding wings.

Worked out good for us. That extra 1,000 government employees bought houses in our subdivisions. :-)