Correction and update.
I know it seems to be boring. I don't plan to do it too often as it's...
However the challenge could be a funny break of normal foiling.
I did it on Sonic15 and SabFoil "Comet" in wind 10-7kts two days ago.
Tried to do 100 tacks in a "narrow channel" style ( viewtopic.php?f=196&t=2403248
) but the wind decreased and couldn't execute the tacking so quick.
In this case the virtual channel was 40m wide. I stop counting the tacks at around 60 as I touched water twice.
In total - 88 tacks in 15m33s (a tack every 10,6s), distance covered 5,28km with average speed 20,36km/h.
A narrow channel style - 46 tack in 6m34s what gives a tack every 8,5s, distance 2,00km with average speed 18,4kmh.