I did not speculate on the REASON.
In the Navy, you would describe this as dead stop, dead in the water means propulsion is down. Anchored is dead stop.
I am not sure what civilians would describe this as, but I took your meaning that propulsion was down.
The Alnic anchored off the coast of Singapore late Monday under its own power, pending damage assessments. It suffered a gash toward the front of the ship, the Stealth spokesman said, but the damage was over the waterline.