this will be over a hot tub
Have you seen the Triangular shade "sail" they sell at Menards? they are a woven material that has grommets on the corners and can be hooked on to any overhead frame or structure? I have a pool and thought about using one over to create shade...
Few ideas for you..
Shade cloth is easy to cut to size. You can buy it in different colors and widths; it is not expensive. I have seen a system where you could fasten a pole frame to your deck railing, then run wires from that to the roof of your home. Then you space grommets along the edge of the shade cloth and you can slide it over the tub, or push it back to have some sun. Easy to disassemble, too. BTW, have you ever heard of a Softub? They are amazingly well insulated and need no plumbing or wiring other than a hose to fill and regular 120 to plug into. Much lighter weight than a regular spa, too.