Preparations are under way for HMS President to leave her berth near Blackfriars Bridge early next month to make way for works on the Thames Tideway Tunnel.
Built as HMS Saxifrage in 1918, the ship has been moored on Victoria Embankment since 1922.
Until the 1980s she was used by the Royal Naval Reserve, and since then she has had several owners and uses.
But now she must leave the Embankment to make way for works on the Thames Tideway Tunnel or 'super sewer'.
Work is due to start on Monday to reduce the height of the vessel's funnels and masts so that she can fit under Blackfriars Bridge and make her way to the River Medway.
HMS President is expected to depart for Chatham at 7am on Friday 5 February.
In 2014 HMS President was turned into a work of art as part of the Dazzle Ships project to mark the centenary of the start of World War I.
President's current owners hope to return her to the Thames but no permanent mooring arrangements have been confirmed.