Paul Robert Mueller was a Gunner's Mate, 2c, in July 1917, and was assigned to a chaser during the war. Due to an injury (a crate being loaded into a sling fell on him), he was discharded on 23 October, 1918.
No record of which chaser he was on.
Thanks to Karl Mueller, his grandson, for submitting the photo scans to The Subchaser Archives.