but what if Prada or Ineos destroy their boat in the last race of the round robins and don’t have time to rebuild it, and US go through without having completed the qualifying rounds?

yeah..there’s a reason you don’t see those anymore 🙂

I had three. Definite one trick ponies. But on the right day they did work. My Tinkler tails were both better all round. Once I got all that out of my system a good conventional board was better. Because by then we’d learned how to shape windsurfers properly, oh, and the rigs had improved too.

maybe they should learn to sail without doing that?

I think there was a fair dose of bad luck with the wind there. I’m sure all the other teams are just glad it wasn’t them that got unlucky.

but what if Prada or Ineos destroy their boat in the last race of the round robins and don’t have time to rebuild it,

They should probably include “not crashing and sinking” in their race strategy then.

I think there was a fair dose of bad luck with the wind there

also a fair amount of bad decision making..you could hear the tactician saying “this (the tack into a gybe) is going to be a very hard manoeuvre”, “the gybe the other way would be safer”…and the helm overruled him

RYA doctrine for Youth Squad / L4 back in the day was ‘To finish first, first finish’ – very appropriate bearing in mind how fine the cutting edge is with these things. The margins for error are a lot skinnier than, say, a Laser 3.

I’ve got an image in my head of them taking a chunk out of one side of the old boat and it ending up like asymmetric wave boards from windsurfing.

My (comprehensive) school used to get sailing boats from wherever it could to compete in the Surrey Schools against very well-funded teams from the local private schools. One wooden Enterprise we rescued from a field, Mr Incredible, was astonishingly competitive on Olympic courses. This may or may not have been due to it being about 3/4″ narrower on one side at one of the key class measurement points. Until we found that out, I thought I’d been finally getting half good…

jeez…haven’t heard that for years….you must be as old as me…I had a Mistral Challenge Flex 🙂 (I think it might still be in my attic)

Yep, I had a Challenge Flex with both tails. I still dont think it was as flexible as my old Mistral Tarifa. Now that really did bend in the corners.
My custom Tinkler was a Lodey I smashed the tail off in the Canaries and had a new flexing tail fitted by Alan Neighbour. Flex was controlled by wedging different sized bits of rubber from car exhaust hangers in there.

If it had been further inboard, with the sheet eased more it would have taken some of the power out

I think that in these boats, during the bear away, easing the main to create twist, when your apparent wind is not on the nose, powers the rig up more, until the apparent wind has got back off the beam and in the right place, unless you really let it go, which these boats don’t/cant.

to ease the sail slows the boat down and *increases* loads as you go around the corner

True – downwind you want to be going as fast as possible when gybing as loads on the rig are lower, but they’re sailing faster than the wind anyway so I’d have to think about this.

whereas keeping the thing sheeted in leads to fast acceleration and a reduction in loads.

Well I dare you try this in a blow. If you try to bear away without easing the main you stand a very good chance of the the rudder losing grip…. especially one with a high aspect foil section. If they lost grip (or had cavitation) then they would lose the ability to control the back of the boat.

The running backstay’s job is to control the forestay tension – not to adjust the power in the main…. they have other systems for controlling the depth of the sail within the sail itself. So I’m not sure of the importance of the runner not being released other than holding the boom inboard – but then the boom doesn’t go very far outboard on these things anyway. If you want to dump power from the main quickly you dump the vang (or whatever system they use to controll the leach tension) – open the upper leach and the power leaves the top of the sail.

If you look at your pictures above, in the top two the leeward runner is very eased and yet the boat has taken off – I don’t even think either were at a mark roundings/bear away either which may point to it being more of a rudder cavitation issue.

then there’s the question if why the runner wasn’t released…. Schoolboy error.

If you watch through the press conference he addresses this, there’s only enough slack in each system to deal with the normal range of motion, so even when eased the backstays don’t fly off like they do on a normal keelboat, they’re just slack enough to allow the top of the sail to twist.

But the wind is still horizontal, so I don’t think the angle of the mast matters.

Even on a more normal dinghy, it makes a big difference. You can try to sail it with the mast canted slightly to windward then the rig generates lift. More important on a foiling moth, but still worth a few tenths of a knot in something more mundane as it reduces the wetted area of the hull.

Also, the wind isn’t horizontal and homogenous. It’s quicker higher up, hence you need to twist the sail to suit it as the apparent wind angle is greater. It also has a vertical component in a gust. They talk about “pressure” rather than gusts because that’s what it is really, it’s areas of descending air that then have to accelerate out when they hit the ground. So if you get caught heeling in one then that air really is pushing downwards on the sail.

Why would the rudder foil hold the stern down….the foils provide lift

Assuming the physics of small boats still holds true then the rig is pushing the boat sideways and forwards. The sideways component is countered by the keel/crew normally and you don’t notice the forward component as boats are so much longer than they are wide. But once the loads increase it’s hugely significant (look at where the crew put their weight downwind even in a non planing/non spinaker boat). So the foils will have to counter that because unlike a dinghy you can’t just move the crew weight aft. I’d guess the optimum rudder would be neutral? But that would be very wind strength dependant.

Although, like the rig I’d assume the trim tab only does so much once it’s no longer moving vaguely parallel to the surface (e.g. when it took off) I’m guessing it’s producing a lot of lift.

Pressure is proportional to wind speed squared, so 15kt to 25kt is 2.8 times the pressure. I’ve read somewhere that the race window for the AC is up to 23kt, so 25kt is more than than the boat is designed to race in.

then they aren’t suitable as an offshore race yacht

That’s probably the very last thing they were designed to be!

so, ghost races for the round robin events the US should have been in….the opposition just have to turn up and cross the start line to collect the point. That’s going to make fascinating viewing….:-)

Where is the best place to follow detailed analysis & comment? The main media is pretty useless.

Where is the best place to follow detailed analysis & comment? The main media is pretty useless.

@danstw13 If you can cut through the antagonism and bullshit and enjoy wild speculation then there’s some good reading on the sailing anarchy forum.

Livesaildie doing a good job as ‘proper media’ too.

Tom Morris on youtube (Mozzysails) also putting some good analysis out.

Yep, as in any fast boat, you don’t bear away if the boat is healing, all it does is lift the back of the boat, then the rudder gets air to it and lets go.

This made me chuckle. Link to IG story where an Australian 49er team has a ‘similar’ experience to the Americans, leeward heel and all. I’d say that whilst many of the principles are different, you absolutely have to keep a foiling boat flat or heeled to windward to survive a turn at the top mark.

I will say it again – I think they are closer to planes and many sailing norms and physics are just totally different….normal expectations don’t really apply

Foil cavitation/ventilation has been known about for decades in windsurfing (maybe surfing also but not sure) – it’s certainly not new.
Ineos had a new rudder design as part of the post-WS upgrade package as they had instances of “losing grip”.
The physics are still the same as water is merely very very thick air!