257. Where a propeller shaft passes through the hull, which device prevents water from entering the hull?

A stuffing box seals the propeller shaft where it exits the hull, preventing water ingress. This device, also known as a shaft gland, is specifically designed for this purpose at the stern tube/shaft log, unlike a stop-water which seals joints, a sea cock which controls water flow in piping, or a propeller boss which is part of the propeller itself.