Twin screwed ships can run their engines in opposite directions and rotate around without moving forward or aft. It's called casting.
The old-timey aircraft carriers would chock and chain their aircraft along the flight deck edges, fore and aft, port and starboard, pointing outboard, and by revving their engines in various combinations could rotate and translate the carrier in the desired direction.
Jay, which Perry-class is your BIL on? I served on the Wadsworth AKA The Mighty Wad.