North Korean Ship Fails/Capsizes at Launch in Front of Kim 1

[racookpe1978]

Details from the available British Commercial Press are few, and what is published contradicts itself.
"
In a statement KCNA said: 'Due to immature command and operational negligence, the parallel movement of the bogies could not be guaranteed, resulting in the launching sled in the stern detaching first and causing the ship to capsize.

'The ship's balance was destroyed due to a rupture in the hull in some sections, and the bow section was unable to detach from the keel.'"

Basically, a North Korean frigate (about 5000 tons displacement) either capsized or rolled off of its forward launch platform when a "dolly" collapsed during the movement.
My assumption is that it was a sideways launch using two cradles, and the stern cradle released first. The bow was still fixed, and the hull torn apart as the ship twisted. The ship did not "capsize" in the water, but rolled over on the launch rails.

Several workers were killed, others injured. But, this is in North Korea. And, in North Korea in front of a public ceremony in front of their Leader. Many more will be killed in retribution for the insult to the Leader. And their families, their relatives of the workers, designers, engineers, and shipyard crew.

Strategically, obviously their Navy is hurt by the loss of a future ship, and the damage to the shipyard and its docks and launch gear. And, any losses to the North Korean arms build up helps the world. But, instead of a "lessons learned" improvement, they will lose dozens (hundreds ?) of irreplaceable launch crew and workers in punishments that will delay future construction for years.

 

[Tomfh]

What do they actually cut to make it go?

 

[Alistair_Heaton]

Clyde it was none galvanised 50mm bar.

There is some thing technical as well I seem to remember with the amount of potential energy they release and acoustic shock loading of the vessel.

We had a ship wright in our reserve Royal Engineer squadron who was a master of all things metal.

 

[TugboatEng]

This is for an air bag launch with only 1 or two restraints.

I think when doing a launch the load is sufficiently high that it can break any partially cut restraints which helps synchronization.

 

[racookpe1978]

This is a short video of a short (3-bogie) sideways launch success.
The three frames released at the same time, all three frames slid downhill equally quickly, the load (the ship) was evenly balanced on the timbers above each frame, and it evenly floated (splashed) up off of the three roller frames.
And the ship was properly ballasted to refloat evenly after being tipped very far sideways. Even at the early stage of construction, all of the installed weights were properly balanced and accounted for.
And the ship was properly watertight, so it didn't sink after being set in the water.

 

[racookpe1978]

And, a very rare! - accurate and descriptive video, of the different launch methods.

But notice the shipyard crews cutting the restraints and the toggles or chain links. One failure on one cable? The crew is murdered. Or learns an expensive lesson.