This is somewhat off-topic, but a fun read: the remembrances, thirty-six years afterward, of the captain of one of the
mortar schooners employed by Admiral Farragut to against the forts below New Orleans. The design-related highlighting is mine.
The entire article, including the sea passage, is at:
https://books.google.com/books?id=wLBYAAAAMAAJ&pg=PA173
The Mortar Flotilla, And Its Connection With The Bombardment And Capture Of Forts Jackson And St. Philip.
A Paper read by Lieutenant George W. Brown, Late U. S. N., at a Meeting of the Commandery, State of New York, Military Order, Loyal Legion, May 2, 1888.
Dur1ng the latter part of the year 1861, Commander (now Admiral) David D. Porter conceived the idea of using sea-coast mortars afloat for the reduction of forts. Consequently, some twenty schooners that had been purchased for light cruisers were fitted out with one thirteen-inch mortar each, and from two to four guns broadside. The preparation of these vessels to carry and use this heavy piece of ordnance required very great care.
They were filled in almost solid from the ceiling to the deck with heavy timber, to enable the deck to withstand the effects of the recoil and concussion. The mortars, or "chowderpots" as they were generally dubbed, measured about four feet across the muzzle, and say five feet in length, and weighed eighteen thousand pounds; the carriage, of iron, about ten thousand pounds; and the bed, or table, seven thousand pounds—in all about sixteen or seventeen tons. The vessels varied from one hundred and sixty to two hundred and fifty tons, and carried a crew of about forty men each.
The ship sailed from New York for Key West during the month of January, 1862. I was the first officer ordered to the command of either of these vessels, and, having my choice, I selected one of the smallest—the
Dan Smith—a schooner built for the fruit-trade, and very fast—in fact, the best sailer of the fleet.
The mortar, a vast chunk of iron on a carriage, and that on a " turn-table' mounted on eccentric rollers, brought the ponderous weight high up from the deck, and was the cause of no little concern during the first gale of wind, which we encountered in the Gulf a few days after leaving New York. I took notice that no one liked to pass to leeward of it when the vessel was lying over much; in other words, they always " kept to windward."
….
[sea passage narrative cut out]
Shortly afterward we sailed for and entered the Mississippi, preparatory to the attack on Forts Jackson and St. Philip. A little incident, which proved of great value, happened while waiting at the Southwest Pass for orders to proceed up the river. My vessel was alone; others either had not arrived or had already gone up the river. When we left New York, as a precaution, we were ordered under no circumstances to cast loose the mortar or fire it at sea, as, if by any accident it got adrift with any motion on, it would endanger the vessel being capsized. In port we had exercised the crews in the manual, but not one of the mortars had been fired, and we were going into action, as I thought, "blind."
Considering my "sea-orders" over, and as I was the senior officer present — which every naval officer improves to command somebody—I thought I would assume command (of myself) and try the mortar in earnest; so we went through all the preparations for action; loaded the mortar with a full-service charge of twenty pounds of powder, cut a fuse for four thousand yards, and, after several changes of sighting one side and then the other, I gave the order to fire. The crew, according to the manual, had been taught to "stand in the rear of the piece on tip-toe, with mouth and ears open"; but, as this was real, and I did not just know what the thing would do, I ordered them farther away, while I, with my officers, noted the time of flight of the shell, and the time of sound from the explosion of the shell; after which I took a survey of the deck.
The mortar had recoiled off the turntable back against the side, driving the rear of the carriage into the water-ways, and listing the vessel about ten degrees. The concussion had taken nearly every door off the hinges, the arms-chest and round-houses collapsed, and other slight damage. [Seaman] Pat was the first to call attention. He stood fixed with his hands upon his hips, looking at the mortar-carriage stuck in the water-way. " O howly Jasus, and wouldant I have been in the hell of a fix, if I had stayed where they tould me? Sure me legs would have been gone entirely!" Such really would have been the case.
For my discovery I was rewarded with a "day off," and breechings were ordered to be fitted on the mortars of all the vessels. This heretofore had been deemed unnecessary.