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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6639
Experience:  Structural Engineer
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I am building an upper deck on a pontoon boat. I want to use

Customer Question

I am building an upper deck on a pontoon boat. I want to use 6061 aluminum plate for the floor. The deck is 8' x 10'. The joists are 1x3x.125 6061 t6 on 24" centers along the 10' dimension. (each jost is 8' long if that helps) I have 2 rows of blocking at 32" centers of the same material. All joints are welded. Basically there are 6 - 32"x24" open spans (or less) on the entire deck. What thickness of aluminum plate should I use? The loading would be a maximum of 4 - 5 people on the entire deck.
Submitted: 6 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 6 months ago.
I can help.
Expert:  StructuralEng replied 6 months ago.
I will size the plate, but FYI - aluminum loses approximately half its strength when you weld it.
Expert:  StructuralEng replied 6 months ago.
5/16" plate will work well if you have one or two big sheets. If you use a bunch of smaller plates, then use 7/16"
Customer: replied 6 months ago.
I understand about the welding and loss of strength. As far as the plate goes I wasn't going to weld it. It needs to be removable for various reasons. I was going to screw it down. Anyway, it is a moot point, 5/16 and 7/16 will add more weight and cost than I wanted. I will figure something else out. Probably plywood. I was hoping 3/16" or less would be sufficient.
Expert:  StructuralEng replied 6 months ago.
3/16" would work for strength, but deflection could be quite high.

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