Totally unrelated to the current discussion: I got nerd sniped by something way back around the update. I don't think that it actually affects the vote, but I thought it was interesting, so /shrug
TL;DR Sinking ironclads with simple black powder charges is a) entirely doable and b) requires far less powder than you might expect. An off-the-shelf barrel of gunpowder could have sent that dwarven monitor to the bottom in two pieces. Having looked at historical examples, primarily a list of WWII destroyers that sank instantly after eating single torpedoes, I am
shocked that so many dwarves survived.
The trick is that you're not trying to blow a hole in the ship. You're trying to blow a hole in the
water beneath the ship, which results in a triple whammy. The gas bubble from the initial explosion lifts the ship in the water, which the hull isn't designed to deal with. Then the ship falls into the hole, bending it in the opposite direction. Then the water rushes back in to fill the hole and slams into the ship from below. You hear perfect torpedo hits described as "breaking a ship's back" because that's exactly what happens: the ship folds in half and then disintegrates.
Putting holes in ships basically doesn't work, especially when the ships have watertight compartments like we saw. Shaped charges, which by making the smallest possible hole necessary to project a useful quantity of extremely angry shrapnel, are particularly useless for this task. The defense against a shaped charge is to put a half-inch air-gap between two metal plates; the shaped charge puts a hole in the outer plate and then the angry shrapnel bounces harmlessly off the inner plate. A ship's compartments are exactly that but even more effective because the air-gap is meters wide instead of inches. Any soft targets in the compartment are toast, but the
hole is small enough to be
patched. At worst one compartment will flood.
To support this, I'll cite the warheads on some semi-modern anti-ship weapons.
The P-700 Granit uses a straight HE warhead. The
Harpoon and
LRASM both use simple HE-frag warheads. Torpedoes similarly use straight HE warheads, which I'll dive into later.
Then the question is whether Marienburg would know how to use explosives to sink ships. Given that they're one of the setting's major naval powers, and the
only one that appears to have a harbor to defend, I'd guess that they've put more R&D into naval mines than anyone elese in the setting. So, yes, I expect that Marienburg would know how to design an efficient and effective naval mine.
Now for the size of the explosive that was used against the Dwarven Monitor here.
Looking at historical naval mines, most of them were much smaller than this, likely because they were randomly scattered around trying to hit targets in the middle of the ocean. The remote-controlled naval mines that the US Navy used to defend its harbors from 1880s to the 1950s, for example, appear to have generally had payloads around 50kg. I could believe that mine hit rates down around a tenth of a percent. This mine was deployed against a known target in an extreme bottleneck, so I'd guess its hit rate might well have been expected to be 100%, and it could have been built with a commensurately larger warhead. How large, though?
WWII torpedoes appear to have had a hit rate around 15%, so we'll look at those. They exclusively used HE charges with weights ranging from under 300kg (
early-war German model,
late-war German model,
US model) to 500 kg (
Japanese type 93, the most advanced naval torpedo of the war).
Black powder has a relative effectiveness of 0.55. Torpex, the WWII US standard for torp warheads, is at 1.30. Hexanite, the WWII German standard for torpedo warheads, was "
slightly less powerful than TNT on its own". The WWII torpedoes were designed to engage armored surface combatants displacing anywhere from 2000 tons (
USN Destroyer,
German WWII Destroyers) to 50,000 tons (
USN battleship,
list of WWII aircraft carriers). A single torpedo hit would usually kill one of the smaller vessels, often within minutes:
Royal Navy escort carrier "Struck by only one torpedo, she quickly sank",
US Destroyer "stricken" after one torpedo,
Royal Navy destroyer lost with 220/236 crew in the middle of a convoy after being struck by two torpedoes.
The monitor that was sunk
displaced just over 1000 tons, about half the size of the destroyers I was citing up there. We'd therefore expect the monitor to go down almost instantly to about half as much boom as the WWII torpedoes. Relative efficiency is about half that of WWII torpedo warhead fills, so about 500kg of black powder would do the job. The black powder cited above has a density of 1.65 kg/liter, so this would be about 300 liters of black powder. This is, conveniently enough, about the same size as the barrels traditionally used for things like flour and wine! The "hogshead" is 250 liters, for example.
