The Operational Status summarize the overall combat worthiness of the boat. It is a combination of the power plant effectiveness, the accumulated damages to the structures (including the gunnery). Successive damages, by gun hit, torpedoes or bomb, will diminish the Operational Status down. The status bar will go from green to orange and ultimately red. Be careful to manage your units to keep them afloat, when the Operational Status is down to 0 your boat is a worthless sinking wreck!
The Crew Status is a combination of the accumulated stress and fatigue. The Moral, Training and Experience of the crew will influence the wearing out of the Crew Status through the engagement. Hits and near misses will be the main contributors to the degradation of the Crew Status. A lower Crew Status will affect the overall efficiency of the crew (Gunnery, Repair Operation and launch / retrieve of observation planes).
The boat flooding is represented on a schematic overview. Penetrating impacts on the belt or underwater will flood the hull, this flooding is limited due to the division in watertight compartments.