You still need a visual signal for rescuers to find you as shown once again by this incident in Colorado where they knew his location (GPS/EPIRB) position, yet it still took 2 days to find him! (Your head is the size of a rock on land or a coconut in the water – both nearly impossible to see.) A signal mirror (requiring active manipulation and sunlight) saved him. The passive/continuous See Rescue Streamer would have also been useful.