Underway but stopped and making no way.
Restricted Visibility - 2 Long Blast.

International Regulations for Preventing Collisions at Sea
More information about
Navigation and Fog sound Signals
Others are:
- Sound 1 Long blast where other vessels may be obscured by obstruction.
- Altering course to starboard
- Intention to overtake on your starboard side.
- Intention to overtake you on your port side.
- Altering course to port
- Operating astern propulsion
- In doubt about signal intention or safety of the proposed manoeuvre.
- Vessel making way through water
- Underway but stopped and making no way.
- Vessel Not under command, Restricted in ability to manoeuver or Contrained by Draught.
- Vessel engaged in towing.
- Pilot vessel.
- Vessel at anchor under 100 metres.
- Vessel 100 metres long or greater, aground.
- Vessel aground at 100 metres or over.
- Vessel indicating agreement to being overtaken.
- Vessel indicating agreement to being overtaken.