DickDastardly

Nope, it's to reduce drag via reducing both effective displacement (wave drag) and wetted area (skin friction drag), plenty of designer interviews around that say that. AC75s have shedloads of RM, 7.5 tonnes of boat x a lever arm between the centre of gravity and the centre of lift of somewhere around 2.5, maybe even 3 metres. The Centre of lift (CL) will in theory be on to the straight line between the lift centres of the immersed foil and rudder, and given that the foil carries most of the boat's weight the overall CL will be just behind and inside the foil.

Maybe but the drag at 60 knots boat speed is at least 2.25 x the drag at 40 knots so you'd be needing more horses than that I reckon

You would think so, your logic works, but VOR65's and IMOCAs discovered that keel lift working opposite to righting moment is actually fast. In those cases, because the lift reduces drag faster than the RM increases drive force. I guess could be the case for a foiling AC75 too. It's a bit counter-intuitive for sure, but if the foil has to lift less than the total weight of the boat it can operate at a better Lift / Drag ratio and the boat could achieve higher speeds for the same drive force. Combine a lifting hull form with clever rig trim that lowers the centre of effort (so less RM required at a given drive force) and you're faster than the other guy.

Like any other object moving through a fluid, the drag force on a foil goes up with the square of velocity assuming constant geometry. Google "Drag Equation"

I just spat out my cornflakes

The power required to tow one of these up to over 50 knots would be well beyond the current chase boats I reckon. They can only just get to those speeds without anything in tow...

If you crunch the numbers, 30kts boats speed in 10 knots of wind at say 45 degrees true, apparent wind angle is down around 11 degrees. Interestingly AWA is about the same upwind and down as the boats go much faster downwind so you notice the traveller go down as they bear off around a windward mark then once the boat accelerates a few seconds later it comes back up to where it was more or less. Upwind TWS 10 Boatspeed 30 TWA 45 AWS 37.7 AWA 10.8 Downwind TWS 10 Boatspeed 40 TWA 145 AWS 32.3 AWA 10.2

Except maybe tight_jeans ...

Just no...

There was never any doubt that the SA tensiometer would appear. Top marks for first reply!

Marginally more then a poofteenth

If that’s true we need a different style of boat. It’s boring if losing the start means game over. May as well finish the race at the first gate.

That bow section and the bustle ahead of the rudder are pure IOR design features. That's not an IACC boat.

I thought he was pretty classy.

I crunched the up and down numbers, AWA looks to be around 13-14 degrees both upwind and down so if a boat is set up to fly stable at that AWA then opening it up to even 25 degrees will create massive forces looking to both heel and cartwheel the boat.