No common understanding of the wind speed
When British naval officers in the early 1800s wrote down their observations of weather conditions in the logbook often occurred problems. For what for some might seem like a minor storm, was second only a fresh breeze. It also used the word pelican much kraftg wind, but even that was a matter of subjective evaluation.
Beaufort scale became standard in the British Navy
One naval officer why, Francis Beaufort (1774-1857), had earlier in his career worked out a scale of wind strengths. Many others before him had made an attempt, but as the Beaufort in the 1830s sat on a high administrative post in the British Navy, he made his scale to default.
It described how the sails of a frigate which was common Navy ships behaved under different wind speeds. One point on the scale of time represented just enough breeze to navigate the ship, and further up the wind strength was just a bit of tearing the canvas.
The scale became more accurate
In the 1850s, also began Merchant to use the scale. It had been more precisely because now also measured in rotations an anemometer. When steamships became common in 1916 they went from describing the sails on to describe how the sea behaved, and this was strictly regulated in 1926 when it brought in knots.
Then you define wind force 9 very strong wind (at sea) or gale (land) with a wind speed of 41-47 knots (20.8 to 24.4 meters per second), high foaming waves (7-9 meters) which sometimes breaks, and on land cracked major branches of the trees and roof tiles blown down.
Beaufort scale has 13 steps (0-12) for general use. But 1946 was the extension of the step 13-17, but this is only for particularly extreme cases, such as tropical cyclones.