The port guns were run out and the starboard guns shifted toward the deck center to heel Royal George for work below the normal waterline. This placed the lowest gunports dangerously close to the water, repeating part of the Mary Rose scenario. The small supply vessel Lark then came alongside on the already lowered side to transfer rum, adding more weight. Decayed central timbers reportedly failed under the altered loads, and the ship heeled farther as seawater entered through the lower gunports. A breeze worsened the list. Fallen cannon could not be shifted back before the ship rolled over and sank within minutes.
Chapter · 33:08-35:17
Why HMS Royal George capsized at Portsmouth
Heeling the ship, shifting heavy guns, loading rum on the low side, decayed timbers, and open lower gunports combine into a rapid capsize.