In article ,
TudorHgh writes:
That would be Force 7 on the Beaufort scale, so just below Gale Force 8.
Each full feather represents 2 and a half feather represents 1.

The feathers do not represent Beaufort Forces but units of 5 kn, but by
a happy coincidence it amounts to the same thing for Force 8 (just) and Forces
9 and 10. 50 kn is Force 10 all right but 15 kn is Force 4, not 3.

In that case I owe the questioner an apology. I've been living under
that misapprehension for 30 years or more.
--
John Hall
"It is a very sad thing that nowadays there is so little useless
information."
Oscar Wilde (1854-1900)