NKE High Frequency GPS

After equipping the 60' with professional high-frequency GPS, we were able to analyze the recordings made by Michel Desjoyeaux skipper of FONCIA. We found significant differences between bottom speed and surface speed in a currentless area. This difference in speed is due to the speed of the water layer on the wave. A wave is a transverse wave that carries energy without moving matter. But in some cases, the water layer moves in an elliptical circular motion and thus induces an apparent wind independent of surface velocity. Surface velocity is the speed of movement of the hull relative to this layer of water.

Under pilot: a real wind calculated with the speed melts

When flying in real surface wind mode, the variation in the apparent wind due to this movement is not taken into account in the calculation. The actual wind angle changes according to the speed of this layer of water and the pilot compensates. The speeds observed are of the order of 2 to 3 nds. For example, at 10 nd of apparent wind and at 126° of the real wind, this represents a variation of 10° on the angle of the real wind. By calculating the wind from the bottom speed we integrate the "speed of this layer of water" and therefore, the angle of the real wind no longer varies according to it. The use of a High Frequency GPS makes it possible to obtain:

• A new driving mode that improves handling: THE WIND REEL BACKGROUND mode
• A very responsive bottom speed.

This sensor provides the bottom speed at the frequency of 10 Hz (10 times per second). It connects directly to the BUS nke. The sensor's NMEA output allows it to be interfaced to a PC to use GPS data.