Vinegar and water is very effective at removing hard water spots. Unfortunately, it is equally as adept at removing wax. Which is why we stopped using it.
On my Malibu, I use Hot Sauce as soon as the boat comes out of the water. It is good enough that it will even remove the stains from Powell. And, unlike vinegar, it has no effect on the wax on your boat. I like it so well that I actually bought a 5 gallon container.
For my Lund, I have used their Toon Sauce a few times. I haven't had as much experience as the Hot Sauce, but from what I have seen, it works very well.
https://www.iboats.com/shop/boat-bl...1P7TxN3DADL7IMrtN0BV0nh1pwO2wf-BoCKKQQAvD_BwE