Spritsail rigged staysail or river barges under sail on the River Thames. The nearest barge, seen from abaft her port beam, is manoeuvring with just her mainsail set, having lowered her foresail and topsail and with her mizzen sail stowed. Another staysail barge, seen from abaft her starboard beam, is under sail on the port tack in the background. Her topsail and foresail have caught the wind.