While there is no caption on this photo, the common thread is that all of these boats were assigned to mine sweeping duties in the North Sea after the war.
It appears that the hull numbers are being re-painted at a larger size, most likely a local requirement, for facilitating identification of the chasers.
Note the structures on the bows, some type of large reel-like device. This is a guess, but maybe early in mine sweeping duties the chasers attempted to run sweep lines? In the later accounts it's clear that the chasers' role was to follow the larger mine sweepers, and shoot and sink any mines that floated to the surface. But as with early ASW, we might assume that the tactics for post-WWI minesweeping were somewhat formative. Maybe chasers were rigged with sweeping gear. Or, maybe it's something else entirely.
Thanks to the National WWI Museum for the photo scan.