This is what Force 9 looks like. I took the photo so that I could write about the Beaufort Scale. I've found out that Beaufort was a naval officer nearly 200 years ago and the scale was an attempt to standardise the wind speed reports to help the sailing ships that were what the navy used in those days. He gave accurate descriptions of what should happen. These days it is linked to wind speed. In our case, it mean that the swell was about 10 metres high. It's an interesting example of an attempt to put numbers to something that was difficult to measure at the time.