What is the case use for a bezel with only 13 to 24 markings?

I can only think it’s to provide easy conversion to 24hr / zulu time ..but those numbers are then useless, if the bezel pointer is moved to mark the start of a timing event?

My daughter has asked what this watch might be? Worn by Erika Eleniak in the first series.
Considering the show's theme, I was hoping this might have been a bold colored underwater watch with some sort of segmented color decompression table dial, but it's unclear if it has a movable bezel. Fashion watch?