I was recently sailing off la coruna on a broad/beam reach in 20 k, nice conditions, we were sailing at 7.5-8 knots and leaving most of the others slowly behind us, about 6 or so 30-40ft monos. On
AIS I was watching a new HR 43 mono, 'saphira' 10M
seaward of us and they were doing 8.5k consistently. Definitely one of the better performing yachts I've come across. I think they were flying a
spinnaker.