No... you set your down wind position ... where ever you are on the course.

You sail one minute on port... you sail one minute on starboard. Stop... set the upwind....

This device extrapolates the wind bearing to infinity.. and caclulates your VMG to the wind. your GARMIN is always trying to send you to a fixed point.... not infinity,. so your VMG is to the bearing... not to the wind.


If the wind shifts during the race... You will see it as different VMG's on port and starbord... Hmm... you may not have noticed this shift.