@mackit
I think the diagram with the arrows was designed for surfers/boarders. If you select surf/windsurf spots in the map items, you get the identical diagrams on each spot. These guys are not interested in waves (the total sea) but mainly in swell, swell2 and wind waves to know if they will have a "cross sea" or a pure swell.
The figures in the table are more interesting for sailors.
M