Complex sentence: Each engine was located in a separate watertight engine compartment; in case of a hull breach in that area, only one engine room would then be flooded, and the ship would still have use of the adjacent engine.
Split into simpler sentences: Each engine was located in a separate watertight engine compartment. In the case of a hull breach in that area, only one engine room would then be flooded, and the ship would still have use of the adjacent engine.