A K-class boat combined destroyer speed with restricted bridge control, a battlecruiser-like turning circle, and a hull meant to spend much of its time surfaced. Diving required extinguishing boiler fires, lowering the two funnels in opposite directions, sealing their hatches, closing ventilators, and checking numerous openings. Commanding officers sometimes walked the deck with extra hands during the evolution because one missed intake could flood the machinery spaces. The whole transition often took roughly thirty minutes, while rough water could enter through the funnels before they were sealed. The design therefore depended more on running from danger at 24 knots than on a conventional crash dive, although contemporary destroyers could still be faster.
Chapter · 28:22-34:40
Funnels and boilers turned diving into a half-hour evolution
Poor visibility, a large turning circle, retractable funnels, and many ventilation openings made the K class difficult to handle and slow to submerge.