If you are still seeking information on boat howitzer drill, we are in the process of reprinting Edward Barrett's 'Naval Howitzer' through Wind Canyon books. Barrett was Instructor of Gunnery at the New York Navy Yard in 1863, teaching volunteer officers basic gunnery practices. In an effort to push through their training as fast as possible, he wrote and published this instruction manual at his own expense. Very concise, very thorough. If not available for immediate shipment, should be ready very soon. Go to http://windcanyonbooks.com/ and use 'naval howitzer' as the search phrase.