Chasers is a collected term for bow chasers and stern chasers, or chase guns. These are cannons mounted fore and/or aft. Chase cannons were meant to slow another vessel during a pursuit in the age of sail. Purpose fit cannon would be lighter with a long bore, aimed for the sails or rigging of the other vessel(s). They may have been fitted on purpose built gun decks or temporarily fitted through gun ports as required.