Bill, My husband bought an off set umbrella at our local Ace Hardware store. Since I wanted a pergola, I am totally NOT impressed. I think it depends on the situation and location. My tub is on a deck and the base of the off set umbrella takes up too much room (it can be bolted to the deck). I slid the base under bottom of the deck rails to keep it stable.
My thought was a pergola that I could make a canvas top for to protect the tub from the summer sun or to allow us to use the tub in the rain.... And then I could remove it to enjoy the stars at night. The umbrella could be used to shade the tub if we were using it in the day, but we couldn't leave it up if we weren't home. The other day a fast moving thunder stom came up and I had one heck of a time getting that umbrella down and out of the way while fighting the wind. So my analysis is that it doesn't do what I want, so I don't like it. :-/ And I will just have to build my own pergola!
I am sure that others are very happy with the umbrellas, but they may not be worried about protecting the tub from the sun on a daily basis.
