Of Course Kim Jong Un's New Destroyer Capsized. The North Koreans Packed Too Many Missiles in a Small Hull.
A launch accident doomed an unstable vessel.
The North Korean navy’s newest destroyer capsized during launch at a shipyard in Chongjin on Wednesday. North Korean strongman Kim Jong Un, who was in Chongjin to observe the sideways launch, declared the sinking a “criminal act.”
But an accident may have been all but inevitable. Apparently desperate to build the most heavily-armed warships possible but constrained by their limited expertise and resources, North Korea’s naval architects designed an extremely top-heavy vessel.
Displacing just 5,000 tons, North Korea’s new Choe Hyon-class destroyers nevertheless pack a whopping 74 vertical missile cells, eight slanted missile launchers and additional launchers and guns. By comparison, a U.S. Navy Arleigh Burke-class destroyer displaces 9,900-ton and has 96 vertical launchers plus topside weapons.
The North Korean ship is nearly as heavily armed as the American ship despite being half the size. And since missile cells are high in the hull, they tend to drive a ship’s center of gravity toward, or even above, its metacenter.
At-sea stability
The math is complicated, but the bottom line is that a stable vessel—one that can roll in rough seas and right itself—has a metacenter that’s above its center of gravity and its center of buoyancy. The temptation to pile weapons onto a relatively small hull risks violating this tenet of sound naval architecture. It was a temptation Pyongyang’s architects obviously couldn’t resist.
That’s not to say the destroyer, the second in the Choe Hyon class, capsized because it was unstable. Instead, it apparently flipped over at its pier while sliding sideways off its slipway into the water. The stern slid faster than the bow, creating a corkscrew motion that twisted the ship to starboard and plunged the stern into the water.
But the high center of gravity sure as Hell didn’t help—and could also endanger Choe Hyon. That ship successfully launched last month.
Satellite imagery depicts the second destroyer partially submerged on its side—and covered in a huge blue tarp.
There are sure to be consequences for some combination of shipyard officials, naval officers and the destroyer’s designers. “Kim Jong Un made stern assessment saying that it was a serious accident and criminal act caused by absolute carelessness, irresponsibility and unscientific empiricism ... and could not be tolerated,” North Korean state media reported.
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