All aluminum alloys are not created equal. 5052. T6-6061. What the heck do these numbers and letters mean? And more importantly, which one should I choose for my boat project? Like most questions related to materials, the answer of course is “Well, it depends on your application.” To understand which is the appropriate aluminum to choose, it’s important to know a little bit about aluminum, its various alloys, and their properties.
Aluminum is an amazing material. Most can easily recognize one of its most distinctive qualities: weight. Compared to other metals, aluminum is incredibly light. It weighs about 1/3 as much as steel, yet has the strength to be used in structural applications, can be used in most fabrication processes, and can be cast, forged, formed, welded, machined, etc. Additionally, it’s particularly great for things that move, and combined with its exceptional resistance to corrosion, makes it an obvious choice for boat construction.
The Aluminum Association of the United States has developed a naming system for the various alloys found commercially available, of which there are over 500 registered designations. Of the commercially available variations, four are most commonly used in the Marine Industry: 5052, 5083, 5086, and 6061. Typically, these alloys have a heat number of H3, which means they have been strain hardened and stabilized.
All 5000 alloys use magnesium as the principal alloying element. This makes the aluminum easier to weld, which is important for construction. It’s generally the “softest” of the four, and because of this it’s also considered the most workable. This aluminum alloy is not as susceptible to cracking during the forming process and is also the least expensive of the common marine alloys. 5052 is generally used for interior parts of the boat such as cabins, decks, and gunwales.
Aluminum alloy 5083 is commonly used by the US Navy. It’s stronger than 5052, yet it’s still formable and easily welded. This aluminum alloy is widely used in chemical and marine environments where corrosion resistance is crucial and can also withstand extremely cold temperatures without becoming brittle. But, all these great properties come at a higher cost than 5052, and although 5083 is stiffer than 5052, it’s also more prone to cracking. 5083’s corrosion resistance and toughness make it a great choice for hull bottoms and side sheets.
Considered the superior alloy for marine environments, 5086 has similar characteristics of 5083, but with added strength. This alloy is so close to its 5083 brother that the two are arguably interchangeable. In fact, 5086’s strength increases when it is cold worked. The main benefit of this aluminum alloy is its increased corrosion resistance properties, especially in salt water. It is the most popular choice for hull bottoms and side sheets.
This is a great general-purpose alloy. 6061 aluminum alloy can be used for structural components, as it has more strength than the other three listed above. It also has excellent finishing characteristics, so it can be used in areas that are highly visible to increase the aesthetics of the project. This added strength comes at a cost though, as this alloy is not as easily formable, is more prone to fracturing, and is only available in limited sizes. 6061 is commonly used for extrusions or exterior hull reinforcement, such as keel linings.
At Naimor, we partner with clients to maximize simplify the boat building process. We work with naval architects, designers, builders, and fabricators to help them build the best boat possible. Our programmers are capable of unpacking complex 3D geometries and working with designers to produce repeatable, manufacturable components. We’re experts at sourcing materials and nesting parts to maximize sheet utilization and lower costs, and if we are able to find an alternate sheet size or material to save money, we pass those savings along to our customers. Check out our 7 Steps download below to learn more about how we ensure quality boat builds.