mortar shooner "thunderer"

[mortarmaker]

Here's a cool picture I found at a sale. It's an old Harper's Weekly illustration. July 18, 1863

   

The caption reads: The bombardment of Port Hudson- A mortar shooner at work- Sketched by a naval officer.

[cannonmn]

That would most likely be a 13" Siege and Seacoast mortar M1861 in the Army's nomnclature.  The Navy used more of this model during the Civll War than the Army did.  Abraham Lincoln directed that many of these mortars, actually ordered by the Army, would actually be delivered to the Navy.

[Evil Dog]

Seems to me I remember reading somewhere that upon firing the boat (or is it ship?) would visibly sink about 2 feet into the water.... vertical recoil?

[MikeR C]

I'm not sure how smart it is to all crowd up directly behind that monster when it's fired!

[Artilleryman]

Where else are you going to stand on a ship?  The only thing to worry about is the friction primer.  I have been within ten feet to one side of one when it was fired.  The only hazard that I experienced was the hot ash that fell down my shirt collar.

[Terry C.]

As big as the 13" seacost mortar is, I've seen photos of Dahlgren pivot guns that were probably heavier and generated more recoil.

[MikeR C]

I don't know, I've heard too many stories about those cast iron guns coming apart to want to stand around behind one. Wouldn't it be fun for one of the trunnions to shear off and have that thing in your lap!
Speaking of hot things in your shirt, when I was a kid, I was gas welding and a 1/4" ball of steel dripped into the back of my high-top tennis shoe and my Dad about had a heart attack laughing at me dancing around till it cooled off.

[KABAR2]

The ships that carried these were purpose built for this task being over built & beefed up to withstand the pressures exerted on the hull when fired.
Remember much of the recoil is downward, the hull structure must not only withstand the recoil
but also the pressure exerted on the hull from the water.

[Cat Whisperer]

I'm not sure how smart it is to all crowd up directly behind that monster when it's fired!

If it were in a Naval mount, I would think that it would be secured to the deck/structure and would not slide.

If it exploded, most of the metal that goes airborne travels in lines perpendicular to the axis of the bore.

[Artilleryman]

I do not remember ever reading or hearing about a 13 inch seacoast mortar blowing up.  So from a historical point I wouldn't worry about one blowing up.  I would be more concerned about one of the big Parrotts.  By the way, if one did blow up, just where would be a good place to stand?  I'm thinking the next county, or a deep hole in the ground.

The one that I worked on did recoil (slide) about a foot.  The charge as I remember it was 5 lbs of powder behind a 200 lb shell, range was 1 mile from an elevated point. 

[cannonmn]

>13 inch seacoast mortar blowing up.

None did.  Cast iron improved via improved process and materials until by about 1850's the measured tensile strength of US guns was around 30,000 psi.  Also the 13" mortars were all cast on the Rodman internal cooling process, as were the 15" Rodman guns and many others by that time.

Interestingly, I talked to a person who was going to reproduce a 13" mortar and told them I had read in the National Archives about how the internal cooling process had been used on that model, and they did not want to hear that information.  Oh well.

Someone was posting on discussion boards something about cast iron guns degrading over time in strength, but I can't confirm that at all.  I talked to a noted cannon expert yesterday who said the only iron cannons he's know to have had accidents (bursting) were either ones that had been submerged in water for a long time, particularly salt water, or those that had been grossly overloaded.  One in the latter category had been at a party in Michigan ca. 1999.  The inebriated participants loaded it to the trunnions with back powder, then stuffed in wet newspaper wads.  A large fragment hit a woman 600 feet away and killed her.

[Terry C.]

Is there a compilation somewhere that lists deadly gun explosions during the Civil War?

It would be interesting to see the stats, and what the worst offenders were.

I would venture a guess that late-war Confederate iron cannon would rank pretty high on the list.

[cannonmn]

Is there a compilation somewhere that lists deadly gun explosions during the Civil War?

Yes there was, at or just after the CW, I think it was Congress that asked for the report, and it was done and published by the government, and I've read it. 

The larger Parrott rifles as I recall won the prize for highest percentage burst.  Some Sawyer rifles burst.  Not a single 3" Ordnance Rifle burst, ever, from what I can tell.

The report covers only Union ordnance as I recall.

If I can find it in a reasonable time, I'll put the citation here.