This is a fun photo. Of course, this was taken under controlled conditions, so don’t try this at home. The photo was shown to prove a point, that the material which makes up an automatic pool cover is even stronger than the ASTM static test that it’s required to pass. The fibers are strong woven polyester which are laminated or coated, or heat molten with PVC resin to give it added durability not to mention strength.
Many manufacturers sometimes treat the cover fabrics with products that give the material UV resistance as well as fade, abrasion, and chemical resistance.
Other tests each automatic pool cover must pass in the lab is for ripping, tearing, or any other sign that the material could fail, such as pulling, or gouging. The current static weight that is required for the pool cover to hold is 485 pounds. Sounds like an arbitrary number, but it’s the average weight of two adults and a child, which was determined by simulating two adults going onto the cover to rescue a child.
You can’t be too safe when it comes to your pool cover.