It’s good that the ranking system tells us that Brookes A, who recently beat both Blue Boats in separate matches, should be faster than Trafford B, but the more important comparison for most club rowers will be the likes of Agecroft C with a CRI of 1521 beating Vesta B, who had a CRI of 1887, by almost 2 minutes and 175 places.

So whilst 80% of crews have CRIs below 2000, a CRI below 2000 tells you very little about that crew’s speed.

It’s important to consider the effect the tide and wind changing throughout the races might have had on the correlation between CRI and time. Usefully for this analysis, at HoRR, most of the crews were set off in close to CRI order, and the wind didn’t change much over the course of the race. Crews with higher CRIs therefore set off on a more favourable tide than those with lower CRI but under similar wind conditions. So the changing tide should have increased the correlation between CRI and speed at HoRR above what is actually inherent to the system.

Looking ahead to regatta season, crews with the highest CRIs will go into “champ” events, the next bunch into a “second string” events and so on. Therefore another important test for the new system is how well it can be used to group crews of a similar speed.

Grouping WEHoRR and HoRR crews by their CRI into ~50 boat divisions shows that there is an average of ~80% overlap in the speed of crews between adjacent divisions. The huge amount of overlap means that a crew taken at random and placed into the division above them would most likely see their position within the “higher” division change by only about 13 places compared to the division they actually race in. Furthermore, at WEHoRR, there were several crews who managed to beat every crew who would be placed in a higher division than them.