$WIVWT

Summary
NMEA 0183 True wind angle in relation to the vessel’s heading, and true wind speed referenced to the water. True wind is the vector sum of the Relative (apparent) wind vector and the vessel’s velocity vector relative to the water along the heading line of the vessel.  It represents the wind at the vessel if it were stationary relative to the water and heading in the same direction.

Syntax
$WIVWT,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>*hh<CR><LF>

Fields
<1>    Calculated wind angle relative to the vessel,left/right of vessel heading, to the nearest 0.1 degree
<2>    L = left, or R = right
<3>    Calculated wind speed, knots, to the nearest 0.1 knot
<4>    N = knots
<5>    Wind speed, meters per second, to the nearest 0.1 m/s
<6>    M = meters per second
<7>    Wind speed, km/h, to the nearest km/h
<8>    K = km/h