Grounding is an additional analysis environment option for the Equilibrium or Longitudinal Strength analysis. It is possible to specify grounding on one or two points of variable length. The Equilibrium analysis will determine whether the hull is grounded or free floating and will trim the hull accordingly. Damage can be specified concurrently with grounding.

If the vessel touches one or both grounding points, this will be reflected in the results:

The displacement column will show the total grounding reaction force in brackets; the sum of the buoyancy and the grounding reactions equals the loadcase displacement.

The effective centre of gravity will be modified by the grounding reactions – a mass is effectively being removed from the vessel; this will bring the effective centres of gravity and the centre of buoyancy in line vertically. The value of KG, GMt and GMl are all calculated to the effective centre of gravity. Remember that KG is measured in the upright vessel reference frame (normal to the baseline); whilst GMt and GMl are the actual vertical separation of the metacentres above the centre of gravity in the trimmed reference frame normal to the sea surface.

Note:

Grounding points are considered to span the transverse extents of the hull and therefore constrain the heel to zero. The length of the grounding points is only used when considering the load distribution for Longitudinal Strength analysis and not to determine the pivot point. The vessel is considered to pivot at the centre of the grounding point.

When two grounding points are entered, the first point (edit boxes on the left) must refer to the forward grounding point; the second grounding point is the aft grounding point.

Note: Fixed zero heel during grounding analysis

The equilibrium analysis will only consider the longitudinal balance of moments, i.e. the vessel will not be balanced in heel and the vessel will remain upright (zero heel) even if the transverse metacentric height is less than zero.