We looked into that as well, but always wanted it within the design instead of over the top. But, apparently, the cost to fix a cover that's on the inside vs. the top was really expensive. So, even if you do have to replace it, it will cost less than replacing the one on the inside which you have to do eventually anyways.

Let me share my experience. Here's our pool.
{{gwi:1321886}}

We have an on-deck track system See the half-a-hexagon thing? See how it's kind of sticking up higher than the rest of the deck? I don't know if that's the pool design, or if the installer didn't do that part correctly. Either way, our cover did rub on it and had to be patched. We're going into our 3rd summer and the patch had to be put on after the 1st summer. I really think it was our PB's fault as I distinctly remember him stepping on the wheels to lower the cover after we complained about stuff blowing into our pool. (Which was also his fault because he didn't measure the cover to be long enough with enough overhang.) But since the patch it's been great and the cover company raised the wheels when it was patched and doesn't rub nearly as much. I originally wanted an undermount cover, but the PB said it would be a lot more costly and he thought the hex part might eventually break off since there wouldn't really be anything supporting it- it would basically be suspended in air. I knew for sure I didn't want a square-shaped lip of cement all the way around the pool (If that's what you mean by "pool in a pool"). Like this:

I think it would be a tripping hazzard. I wish I would've talked to the cover company myself instead of trusting my PB because they probably would've come up with a better solution. It certainly looks like they can do an undermount on a free-form if that's what you want.

Sharla and Southernmum,

If you look at the pictures in all the brochures of the automatic pool cover companies you will see their beautiful covers laying perfectly flat on the pools. They have over-filled those particular pools with water to give you the idea that your pool cover will look the same. Sharla, you already know that the cover droops and sags and your options for in the deck or on the deck installation of the cover is somewhat limited by the type of pool you have. With a free-form gunite pool you have the ability to get creative with the tracking system as is shown in one of the pictures you have included. I assure you the added expense of this method on top of the huge cost of an auto cover is beyond most peoples budget. Your pool looks like a fiberglass pool. Some manufacturers are making some rectangle fiberglass pools that will allow for the auto cover track to be installed in the pool, just underneath the cantilever edge. My guess is that your pool builder had to pour the deck a little bit high in that area so he had enough fall in the deck to keep water from pooling in the little flat area behind it.

Any updates? I know this is an old post..