Herakles (pusher) the fuel supply and lubrication system due to the violent pitching of the vessel were not ruled out. On 2 March 2004 the weather in the Bothnian Sea gradually developed into a force 10 storm on the Beaufort scale, with average wind speed around and gusts exceeding . At midnight, shortly before "Herakles-Bulk" sank, the ten-minute average at Svenska Högarn was with three-second gusts of almost . The freezing temperatures combined with strong wind and high waves resulted in fast icing of the ship structures. In 1992 the Finnish Maritime Administration issued a wind limit of for "Herakles" due to
Wind stress of heat and mass between the water and the atmosphere. The air blowing parallel to a water body imparts motion to the surface water by shear action. This is a downward transfer of momentum from the air to the water that ultimately generates a drift current underneath. The water surface also deforms under the action of wind and becomes wavy for increasing wind speeds, which modifies the grip that the wind has on the surface itself. The mechanics of the interaction between wind and water becomes thus increasingly complex. The Beaufort scale, for example, shows the correspondence between wind speed