Union Mortar rafts

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old seadog

Cadet
Joined
Mar 16, 2018
Hi all.
A question on Union Mortar rafts. I understand they were about 65 by 25ft and a 7ft draft. Are there any plans to one of these anywhere? Has any that were sunk ever been re-discovered and surveyed? I am not aware of any. wondering what you all know. Thanks in advance.
 

FenianPirate

Private
Joined
Jul 12, 2015
Location
Rocklin, CA
You've come to the right place, my boy! Yaasss, indeed. In 2011, I researched the little fellers in some depth, turning up a new resource in the process.

Shortly, I will provide links to a recent plan by the illustrious Ed Parent of Hamilton, MA. Other, (IMHO less accurate) sources are
  • a four-page article about the modeling them by Jack E. Custer: "Union Mortar Scow", Ships in Scale (March-April 1984); and
  • a plan by David J. Meagher copyright 1994.

There are a few others who have taken a stab at plans, none of which reflect an original sketch by Alexander Simplot for a Harper's Weekly engraving of one on the stocks. I rank it one of three or four essential contemporary images for credible plans.

Others are the Harper's Weekly (Simplot) engraving of one afloat, just as it was being fitted out, and a photo from a height of one mounting it mortar, tied up next to a Union tinclad gunboat, and several aging waterlogged mortar boats next to the ironclad Essex. Stay tuned while I round those up.

Meanwhile, I am posting a plan which reflects my research, and some key images.

mortar boat plan - mod 2.jpg
mortar boat images.jpg
 
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FenianPirate

Private
Joined
Jul 12, 2015
Location
Rocklin, CA
In the Simplot construction sketch you can count the stringers, but in the second image you will find that the engraver took some artistic liberties which lost that detail. For an enlarged version of the sketchbook drawing, click the link to the copyrighted image:

Building Pontoons to Mount Mortars
https://www.wisconsinhistory.org/Records/Image/IM32899

WHS webpage for Simplot image.jpg


Source: Alexander Simplot - Wisconsin magazine of history. Volume 41, Number 4, Summer, 1958.

The resulting Harper's engraving is:

Building Pontoons For Military Use On The Mississippi. Page 646, Harper's Weekly, October 12, 1861

Building Pontoons For Military Use On The Mississippi.jpg
 
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FenianPirate

Private
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Location
Rocklin, CA
A secondary source on the various USN uses of the 13-inch mortar provides this useful summary on mortar boat construction and employment:

Armaments and Innovations - The Union Navy’s Stubby Gun
By Spencer C. Tucker
Naval History Magazine - April 2014 Volume 28, Number 2

"Union Major General John C. Frémont, commander of the Western Department, ordered the first Civil War mortar boats on 24 August 1861. Thirty-eight in number, they specifically were designed to engage Confederate river batteries. Designated by numbers rather than names, the 60-by-25-foot boats were in fact little more than rafts and of such low freeboard that the first two feet of their six-foot sloping sides were caulked to keep out water when the mortars were fired. The sides were slanted inward at the top and plated with half-inch-thick iron to protect against small-arms fire. The boats, which leaked badly, were moved about by tugs and proved so unwieldy that false bows and sterns had to be added to make them more maneuverable.

A 13-man crew, including a first and second captain, manned the mortar. To train the weapon, the platform, or “circle,” on which it was mounted was turned. Crewmen using curved “eccentric bars” inserted into cams along the circle’s edge first lifted the platform onto its rollers and pinned the bars in place. Others then used train tackles to turn the circle. When the mortar was properly positioned, the bars would be unpinned and the circle lowered. Because of the intense noise and reverberations inside the boat when the mortar was fired, after charging the weapon the crew would retire through iron side hatches to the open stern deck. The first captain would then fire the mortar by quickly pulling on a long lanyard whose opposite end was attached to a friction primer inserted in the weapon’s vent.

The first mortar boats were not ready in time for the Union victories in the battles of Forts Henry and Donelson in February 1862, but they joined Flag Officer Andrew H. Foote’s squadron on the upper Mississippi in March and participated in the Battle of Island No. 10 later that month. They also took part in other actions, including the shelling of Vicksburg during the 18 May to 4 July 1863 Union siege of that Confederate bastion.
"

-----

NOTE: I have the greatest respect for Dr. Tucker, but I could find no evidence that his description of the Union mortar schooner aiming turntable applied to the Union mortar boat/scow/raft. The only high-angle photo that I have found (see earlier post) shows the mortar sitting off centerline on an anchored boat, which does not square with the idea of a fixed turntable.

I found mention in my reading (and in the photo of one next to USS Essex), that eventually the mortar boats became waterlogged and were retired. But some lasted long enough to see, with the fall of Vicksburg, completion of the campaign to open the Mississippi River. These boats, the timberclads, and the Eads "City" ironclads are testimony to the vital, early role that General John C. Frémont and Commander John Rodgers played in equipping the Army and Navy for that campaign.

Those of you with USNI membership can view the entire article at:
https://www.usni.org/magazines/navalhistory/2014-03/armaments-and-innovations-union-navy’s-stubby-gun
 
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FenianPirate

Private
Joined
Jul 12, 2015
Location
Rocklin, CA
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.
 
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Carronade

1st Lieutenant
Joined
Aug 4, 2011
Location
Pennsylvania
NOTE: I have the greatest respect for Dr. Tucker, but I could find no evidence that his description of the Union mortar schooner aiming turntable applied to the Union mortar boat/scow/raft. The only high-angle photo that I have found (see earlier post) shows the mortar sitting off centerline on an anchored boat, which does not square with the idea of a fixed turntable.
It makes sense that the simple rafts might not have the same mechanism used on naval bomb vessels, but then how did they aim? Move the whole raft? The presence of capstans on these no-frills craft suggest they might have done just that, pulling on anchor cables or cables secured to fixed objects on the riverbank.
 
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Joined
Sep 28, 2013
Location
Mississippi
Hi all.
A question on Union Mortar rafts. I understand they were about 65 by 25ft and a 7ft draft. Are there any plans to one of these anywhere? Has any that were sunk ever been re-discovered and surveyed? I am not aware of any. wondering what you all know. Thanks in advance.
Welcome aboard @old seadog.

Great question.

I'm aware of at least one of the mortars that exist from the Vicksburg campaign, but I don't think there are any remains of the barges .
 
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