If the ship grounds on a level bottom:

• A ground reaction force acts vertically upwards from the seabed. This force counteracts part of the ship's weight and alters the distribution of buoyancy forces.
• The ship’s centre of gravity (G) may appear to rise relative to the metacentre (M) because the upward ground reaction reduces the buoyancy force acting on the underwater volume.
• This virtual rise in G reduces GM, potentially leading to a list.
• If the list becomes excessive and the righting moment is insufficient, the ship may capsize.

If the ship grounds on a pinnacle:

• The ship experiences two forces at the ship's bottom:
  • A downward force due to the ship’s weight.
  • An upward reaction force is concentrated on the pinnacle.
• The resulting force between the grounding pressure and the ship’s centre of buoyancy shifts downward towards the pinnacle.
• This situation is similar to when the ship's stern touches the keel block in a dry dock.
• A virtual loss of GM occurs because the ship’s inclining moment may exceed the maximum righting lever.
• If the inclining moment is too great, the ship may develop an excessive list or even capsize.