I would like to construct a marine hoist, capable of lifting a total of 20 tons/40,000 pounds. It is really a basic structure consisting of 6 structural steel beams. I will have 4, 16x16, concrete footers poured at approximately 15' X 12'. One 14' beam will bolt down to a footer. The total height is 14'. Another on each footer. On the 15' ends of the hoist, a beam will connect the tops of the two coming from the ground. So I will end up will 2 upside down, 15', U's, spaced 12' appart. Attatched to each of the two upper cross beams will be 2- 5 ton hoists. One on each end. A total of 4 - 5 ton hoists. I need to know what type of steel to use to support that kind of weight. The smaller the steel, the better. Thanks for any help.
I also believe that you better check with a structural engineer. As a minimum you need at least two additional horizontal structural members which should connect the top corners of one of your upside down U sections to the top corners of the other upside down U section to give the entire structure some longitudinal horizontal stability. You might also want to brace from the center of each of these added horizontal members down to the base of each of the vertical U support columns.
You had better consult a structural engineer, before trying anything with that much mass supported on a rig that has no sideways reinforcement. You might injure or kill someone.
