The ship's ability as a patrol vessel was limited by her 9-knot maximum speed. However, the ship was still assigned to seaward patrols against German U-boats, even though the ship was not capable of operating in heavy seas. At the time of the December 1917 Halifax Explosion, Lady Evelyn was patrolling off the harbour's approaches.
The ship's limited speed restricted its effectiveness as a patrol vessel, but it was still assigned to seaward patrols against German U-boats despite being unsuitable for rough seas.  During the December 1917 Halifax Explosion, Lady Evelyn patrolled off the harbor's entrance.