HMS Roebuck (H130) - UK - Coastal Survey Vessel
Roebuck was designed to work in home waters, but was used in the 2nd Gulf War to find the depth of water so that coalition ships could work much closer to the shore thus reducing helicopter flying times.
Seen here at Newcastle March 2010 she was decommissioned a month later and sold to the Bangladesh Navy by May 2010 to sail as BNS Anushandhan.
HMSML Gleaner (H86) - July 2011
Her Majesty's Survey Motor Launch Gleaner is the smallest commissioned vessel in The Royal Navy