bow chaser

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. One of a pair of long guns mounted forward in the bow of a sailing warship to fire directly ahead; used when chasing an enemy to shoot away her sails and rigging

from the GNU version of the Collaborative International Dictionary of English

• n. a gun in the bow for firing while chasing another vessel.

from The Century Dictionary and Cyclopedia

• n. A gun pointed over the bow of a ship of war, for firing at a chased vessel.