Is there an instruction or regulation governing the use and wear of the tan UDT swim shorts - commonly used at BUD/S?

The only instruction or regulation that I remember from my very "brief" tryout for UDTs in 1970, was the rather strong suggestion to make sure the opening was in the front!!! .

Dang. While I was looking, I ran across the boat cloak. It will no longer be authorized after 1 OCT 2016. Too bad ... that was way cool.

If you are asking, as for the use for PT and or in the gym, I don't think there is a instruction covering the use or wear of them. I will say your command may set what ever PT uniform policy they wish, if there is no set PT uniform for unit PT the standard falls back to the US Navy standard PT uniform Blue PT shorts and Yellow PT Shirt. We have Divers inside the Seabee community and they have UDT/Ranger shorts that they use for their unit PT, and some wear them doing personal PT on their own around the base and no problem. We have more people and units conducting PT on the base then you would see at a regular base. I will also say this the UCT divers wear the Green Cargo type shorts when not in dive statues around the compounds and only use the UDT shorts during some PT sessions and for Dive operations. I do not believe there is an Instruction for use and wear of them. If you are talking for your command, I would go to your command PT instruction. I am speaking form the Seabee world and we do things a little different for some things.

I am not sure if I helped, do remember that the fall back to Navy PT is the Navy PT uniform. I will contact some of the Seabee Dive team guys and see if the Navy has an instruction.