Possible Clues:

• One or more large merchant ships
• A cheerful setting for Byng's last ship
• Fleet of merchant ships
• Old merchant ship making ancient city before day's end
• An optimistic setting for grand merchant fleet
• Ship heading off slowly — extremely slowly
• A promising future, for instance, holding key to merchant ship
• One or more large merchant ships
• A word for a large boat from the Mediterranean, apparently not related to a famous boat of Greek myth
• Flotilla of merchant ships