Jeff, sorry for the delay in responding

We use the term Groove to define a period when you are sailing a stable course along a relatively straight line for a significant time. We determine this by applying a proprietory algorithm (the “secret 11 herbs and spices”) to your your track as reported by the watch’s GPS.

Once we have determine you are sailing in a Groove, we activate a bunch of further algorithms to

• re-calculate the TWD (if you are upwind)
• recognise a tack
• identify a mark rounding