The lanyard held a rigging knife, as discussed in this earlier Shorpy post here.

In 1960-61, I was assigned to a multi-service military unit, mostly army and air force, but with a few sailors and Marines as well. I recall the USN types' saying that the flat or Donald Duck hat was issued to all ratings but only worn within the Atlantic Fleet and only with the blue blouse. With whites or dungarees, the white "Dixie Cup" was prescribed; that same white cap served for all purposes on the Pacific Coast and elsewhere in the navy. Apparently, as landtuna observes, the flat hat became obsolete even on the East Coast just a few years later though, typically, still part of the basic issue.

Chief Trouble Officer

More likely pocketknives with a marlin spike for rope work. Apprentices would not rate a whistle, which is used to give commands (similar to the bugle for cavalry, etc.).

The lanyards are for their boatswain's pipes. Making your lanyard remains a point of pride for boatswain's mates, sailors serving in the U.S. Navy's oldest rate. In U.S. service, it has been in existence since the Continental Navy and no doubt existed long before then.

What's on the end of those lanyards?