The posting to Europa suggest your man was in the Royal Naval Patrol Service, many of the men in the RNR at that time were fisherman and the Admiralty had requisitioned trawlers, drifters and any other vessel that were suitable as mine sweepers, boom defense vessels and patrol craft, these men knew these waters well and some went into the Dardenelles area to clear mines.
My grandfather was also in the RNR and a fisherman and from the Moray Firth area.
The remarks in the end column suggests he "went over the wall" absent without leave and was given 7 days in the cells.
The names in brackets are the vessels he was on the other name next to it is the Base or Depot ship that was used as a depot for admin, pay, victuals etc.
James