True wind

Hi, No, I believe you are correct, and in your example: Ground Wind (as explained in the module) = 5 knots from the North True Wind = 0, the Ground wind has been negated by the current. I had some problems myself with this. But I am starting to get to grips with the model.

I also find it a bit confusing.

I believe that "normally" the wind generated by the current should also belong to the Apparent Wind family. It's just that there is no way to assess it using electronic navigation tools, so it is probably a good "electronic" compromise to consider it as a component making up the true wind, which is basically the value you get when the speedometer wheel is not spinning (what Donald refers to when he says "floating with the tide"). But I still find it strange: if I am at anchor, and the current is flowing, my speedo wheel would be spinning, so I would read an apparent wind... ??!!

The wind you need to sail will be the wind relative to the surface of the water. Donald is correct in that if the current and wind are flowing at the same speed in the same direction, then the boat will feel no wind. If the sails were raised, they would do nothing. By the definition given in this course, the true wind is zero. However, I think a weather report would give the true wind at 5 knots (speed over ground), so I also see logic in saying the true wind is 5 knots. You just need to know what is actually happening, regardless of how you define the terms.