How deep should I build foundations to hold a two person hammock?
I don’t have any trees in my back yard but want to have a hammock hanging. I am planning to insert two wooden poles vertically about 12 feet apart and suspend the hammock from these. I also plan to make them removable (i.e. have the concrete foundation with a circular metal tube through the middle in which the wooden poles can be inserted). How deep and wide should I pour the concrete?
You are probably going to use a 4"X 4" post about 10′ long. Considering rain is going to collect in your hole for your post, you really need holes to allow drainage and considering the forces you are going to put on the hole itself, 24" – 30" deep at minimum.
Unreinforced concrete about 18" cubed around your metal tubes should be enough for your design. You could go with a less substantial pour if you incorporated guy wires from your stanchions to inground anchor points.
Good Luck!