Why does my cover lift higher on one side while being short on the other side?

This phenomenon is caused by what we call an inside curve. Adding dressmaking tucks to the curve on some pools, such as kidney shaped ones, will help stop the blanket lifting unevenly, which can be caused by an inside curve. For instance, if you have a kidney-shaped pool, you will find that the material will tend to push from point A towards point B. This is caused by the upturn of the over cut material trying to straighten itself out. It is curved and too large so it creates a force downward. This force is transferred downwards from point A towards point B. If you put some dressmaking tucks into the curve around the A section then this force is contained and the cover will remain stationary.

Kidney bean shaped pool