rQ index represents the quality of the steering on each leg or the race overall. The higher the index the better job the helmsman and the trimming crew is doing to keep the boat sailing strait. The average range of the index upwind for a good Corinthian team between 70-85 and for professional sailors 85 – 95. The index will be higher on the reach and downwind as it is much easier to keep the boat sailing strait on these points of sail. The index will not be affected by smaller and proper course correction – changing the gears or sailing the waves.
The index does not always indicate a better boat, since many boats who don’t point well (footing too much) will demonstrate high index but suffer a lower VMG. The art of sailing upwind is to sail sufficiently high looking for the best VMG without changing the course too much. If the index is too low it is usually due:
– excessive rudder movement and / or
– incorrect sail trim.