If you set the Wind arrow in scale control to  the length of each wind arrow will be the distance you will travel in one hour.
The two Wind filters options allow you to show or hide wind data according to how strong the wind is. If you set the show tws >= to say  then all the winds less then 5 knots will be blanked out on the chart. This is useful for highlighting holes in the wind that you need to avoid.
The wind values shown on the chart are those taken from the Grib files at the 1° Lat and Long ordinates. Remember that if you have Interpolated Winds turned on the wind speed and direction will vary between these 1° points. You can see this as you move the Ruler , Route , and Track tools over the chart.
When you download weather from any of the sources, the downloaded weather is contained in a weather "grid" and is added to list of grids in the window. The grids are automatically named - the name usually (but not always) identifies the area covered, a time-stamp and where it came from.
If you tick the overwrite previous wind grid box, a subsequent download for the and from the and will overwrite an existing grid. This means that when you repeat a download for a later an existing grid will be overwritten. On the other hand, if you alter the of a download there will be no matching grid to overwrite.
This can get quite confusing and you can easily end up with active grids that overlap. If you find that the wind on the chart is different to the game the most likely cause is that you have multiple grids active for the location. As a general rule you should:
- Keep the overwrite previous wind grid box ticked.
- Do all your downloads from a single source.
- Avoid overlapping grids.