Health and sinking

The bar is seaworthiness: how much of the ship's flotation reserve is left. It is not a count of surviving parts. A ship with every gun shot away and a sound hull shows a full bar; a ship with one flooded end shows a low one.

A damaged hull part keeps its weight but loses lift in step with its integrity. Enough lost lift and the ship can no longer carry itself.

• Foundering. With under 3% of its reserve left and its centre of mass under water for 3 seconds, the ship has sunk.
• Swamped. A damaged surface ship wholly under water for 3 seconds with under 25% of its reserve left is lost. Boats built to dive are exempt.
• Capsizing. Past 75° of roll a hull takes on water: 2.4% of its reserve each second at first, rising to 8% a second at 90° and beyond. Keel up, a sound hull empties its bar in 12.5 seconds. The water never drains: a ship that rights itself keeps the lower bar.
• Breaking in two. A hull is as strong as its weakest cross-section. When one section along its length is shot away to between 5% and 15% of what was built there, with at least 15% of the hull still standing on each side, the hull parts and sinks. Slender hulls break sooner than broad ones.
• Crush depth. Any ship held below 200 m for 5 seconds is destroyed. See Submarines.

The bar counts the weakest cross-section too, so it always empties before a ship is lost.

A collision does damage by how fast the ships close, measured square to the face that is struck: a square hit hurts and a scrape does not. The softer side takes more of it, judged by what the struck part is made of, its armor and the ship's weight. A hull struck end on, at the bow or stern, is 3 times harder than one struck on its side.

A heavier ship that keeps driving into a lighter one keeps crushing it and presses it down into the water. Teammates do not damage each other by ramming.