>>211364623
I don't want to watch this shit, but did they mention the specific problem with fiber hull, it's about checking final product for inner defects.
When you use metal you can locate any defects in the wall of the hull, but when you are working with fiber it's impossible because material is not reflective. You can't check if this specific submarine withstand pressure without actually putting it in the water. Awful design flaw.
Rule of thumb, if you can't put your machine on a test bench, don't drive it