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
Fujita scale F1 corresponds to the twelfth level of the Beaufort scale, and F12 corresponds to Mach number 1.0. F0 was placed at a position specifying no damage (approximately the eighth level of the Beaufort scale), in analogy to how the Beaufort's zeroth level specifies little to no wind. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes. The diagram on the right illustrates the relationship between the Beaufort, Fujita, and Mach number scales. At the time Fujita derived the scale, little information was