A safety bonus in case of severe hull damage: America's three-compartment-standard.
The America was constructed to meet a full three-compartment- standard that still surpasses all of todays prominent cruise ships like the Queen Mary 2, the Oasis of the Seas, or other current new passenger ships with their two-compartment- standard.
The America had 14 watertight compartments, of which three could completely be flooded without putting the ship in danger. This means that the structure was designed to ensure for up to three flooded compartments the full stability of the ship, no matter in which area of the hull the damage may occure. In many areas of the ship, the actual value was as high as 4 compartments (see figure below). The calculations for the three-compartment-standard were based on the worst top heavy conditions that may prevail on board: empty fuel tanks and empty cargo holds. If not the engine room or both boiler rooms were part of the damaged compartments, the ship may even have been able proceed slowly under its own power.
The ship's double bottom, (which practically was a double hull in some areas of the ship like the machinery spaces), ran under the entire length of the ship and in sensitive areas, such as the engine room, reached up to the height of the B-deck.
Warnings and signs of the watertight doors were working on the hydraulic "Stone" system. The notifications were since the Australis days also written in Greek on board.
Above: To rase awareness of the closing or opening of a watertight door, there was an audible and visual warning system. The red lights on both sides lit up when the door was in motion, and one was therefore prohibited to step through, the green marked a standstill of the doors. In the event of a power failure mechanical warning sirens were available which were driven by the movement of the door.
Page 2: Sinking of America? Much more unlikely than on many other ships
Watertight compartments of America (scroll to the right to see the forward part of the ship).
Three-compartment-standard of America (scroll right for bow).
Stability of America in case of flooded compartments
The diagram above demonstrates the three-compartment-standard of America based on the floodable length of the ship. You can see the watertight compartments (red lines), the margin line (never to exeed line, otherwise the ship will sink, green) and the floodable lenght curve (yellow), necessary for flooding calculation.
The floodable length is defined by the three curves above the hull, the floodable lenght curves. One for the stern, one for the machinary area and one for the bow.
Onto the hull, triangular areas are marked (for clarity some are highlighted purple colored) that look like pyramids, each with a "3" at the top. This "3" refers to the three compartments, which are each bracketed by one triangle.
Important to understand the calculation: The pyramid's peak must always remain below the floodable length curve so that the three- compartment- standard is maintained and the ship does not sink and remains afloat (so stays above the margin line).
Ergo, this drawing demonstrates, that America is able to withstand a damage (and resulting flooding) of three neighboring compartments in all areas of the hull.
But there's more: The diagrams also shows, that the America even reached a four-compartment-standard in some areas.
To do the calculation for this, simply extend the triangle lines in the area to be examined until they intersect again. If the new intersection point (the new pyramid's peak) stays below the floodable length curve, the ship does not sink.
To see in which areas four compartments can be flooded , the marks for this scenario are subsequently drawn in blue with a "4". In some areas the hull is even able to withstand five flooded compartments (marked in turquoise with a "5").
The America possessed 59 watertight doors, which could be centrally closed from the bridge on a button, or manually in an emergency. When the switch on the bridge stood a lock has been opened and closed manually on site, she joined then again automatically.
The watertight doors were operated by hydraulic systems that were redundant. If improbably both fail independently working hydraulic systems and also manually through the doors no longer be accessible fire or flooding, so there was a hand winch, with which they could be closed or opened by each higher deck. All watertight doors possessed electric sirens when they were in the movement and in the event of a power failure also about mechanical.
But 100 percent safety can never be reached. By an unfortunate combination of circumstances, of course even minor damage can sometimes lead to a disaster. The most important factor in accidents is the prudent and immediate reaction of the crew to take necessary countermeasures. Without a well-trained crew even the benefits of the best safety systems are worthless as sadly proven a lot in the history of ship disasters.