Ventilation Inception on Surface Piercing Foils or Struts

VENTILATION is a problem of long standing associated with high speed hydrofoil craft. The sub-atmospheric pressures, generated by the movement of the foils through the water, can cause air to be drawn from above the free surface to form a stable or semi-stable cavity attached to the foil. When associated with lifting foils, ventilation causes a marked loss of lift and in other instances can result in loss of directional stability.