Backstroke flags are not always present at Allegheny Middle School pool
Generally, swim pools have backstroke flags that make great attachment points for the SKWIM goals. The bungee cord with a hook can be attached from the middle of the floating goal to the backstroke flags. Then the flags are simply lowered for a moment at the outset and ending of the play time to place the hook.
In the photo at the top of the page, the SKWIM goal's cord was put onto the wire that guides the pool blanket. One of the swimmers said that the hook was to be attached much like a zip line. Hardly any pressure goes through the cord to the line or backstroke flags as the goal is very light.
Surf to the various images from the months of on-going development
Best so far is the Bullfrog materials with three layers. But, the leg length should be three high, not two, as the photo shows below.