reserve buoyancy

plural reserve buoyancies

1. countableuncountablenatural sciencesThe ability of a ship, boat, or other vessel to stay afloat even if loaded with additional weight; the additional buoyancy of a vessel above and beyond that required to just float the vessel itself.

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   In the engine room, the changing angle dropped the melted core to the deck. The hot mass attacked the steel deck first, burning through that, then the titanium of the hull. Five seconds later the engine room was vented to the sea. The Politovskiy's largest compartment filled rapidly with water. This destroyed what little reserve buoyancy the ship had, and the acute down-angle returned. The Alfa began her last dive.

   1984, Tom Clancy, “The Eighth Day: Friday, 10 December”, in The Hunt for Red October, Annapolis, Maryland: Naval Institute Press, →ISBN, pages 194–195