The propeller shaft passes through the hull through seals exposed to constant movement and wear. If a seal begins to leak, repairing only from inside cannot provide the inspection and access needed to dismantle the assembly properly. Delay allows more salt water into the ship and can compound damage to machinery and structure. A carrier force therefore needs an appropriately equipped dock within safe reach and available on operational timescales, not merely a theoretical berth somewhere in the commercial market.
Notable Point · 45:43-48:09
Shaft-seal damage makes emergency dry-dock access essential
A leaking propeller-shaft seal shows why some underwater failures cannot wait for a routine commercial opening or a long rough-weather voyage.