They were wearing PFD's and had extra flotation, but for some reason the PFD wouldn't keep the deceased's head out of the water -- not good enough for more than a couple hours. They were also lacking in signalling gear. Meeting the minimum Coast Guard/DoT requirements for gear is fine until you find yourself floating.

A PLB would have ended this ordeal quickly and a signal mirror may have gotten a response from the first manned rig. PFD's can have pockets where critical survival gear can be kept on your person. When you're floating in the middle of nowhere, signalling gear is critical. PLB, PLB, PLB