The howitzers used in the fore and maintops of Faragutt's fleet were boat howitzers most likely heavy 12's. As the Admiral issued his orders all ships were to lash the boat howitzers for firing abeam as they passed the forts. (vol. 18, pg 48 West Gulf Blockading Squadron Fe.21, 1862-July 14.1862. ORN's. Later in the same volume pg 185 in the USS Brooklyn's after action reports the howitzer crews fighting in her tops were singled out for praise.
Geo Dailey
gunnersmate USNLP
(western waters)