I am still in complete awe of these behemoths being able to hit these speeds.



BTW - hope all well with everyone out there in GPS land??!

Anyone got a link to some video footage of the race.

Here:

Check out the readouts from the pair of anemometers at the top gate at 5.30.

Yep the mind boggles alright. Must be some HUGE forces involved where the foil joins into the hull.

There are report that the NZ boat has hit 56 knots on their new foils.

Insane speeds, very impressive! what are the barriers to adopting this style of foiling on a windsurfer? Control systems?

No room for the grinders!

Yep Im absolutely riveted by these boats and races. I wonder if windsurf sails will become adjustable double skin in the future, incredible power and versatility.
I reckon the Italians got robbed against the poms in their last race. Sailing rules are going to have to change for these and other big foiling boats. Anyone that's foiled close to the stern of a power boat or sailing craft knows of the tremendous turbulence given off under the surface. Way to dangerous for these boats to have to pull off the manoeuvre the Italians had to despite being on starboard tack.

Hopefully the Kiwis can defend the cup.

So beyond control issues etc, whats stopping windfoilers from hitting speeds in excess of 50kts? It does seem like with the aerofoil shapes etc, its possible to hit those speeds before cavitation. The cup yachts seem to be happy sitting at 45kts+ downwind fairly consistently

Geometrically, the AC cup yachts aren't super weird like some other things such as sail rocket etc.

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decrepit said..
No room for the grinders!

If it can be done on a RC boat, surely it can on a windsurfer?

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swoosh said..
So beyond control issues etc, whats stopping windfoilers from hitting speeds in excess of 50kts? It does seem like with the aerofoil shapes etc, its possible to hit those speeds before cavitation. The cup yachts seem to be happy sitting at 45kts+ downwind fairly consistently

Geometrically, the AC cup yachts aren't super weird like some other things such as sail rocket etc.

Cavitation.

They may be able to hit these speeds briefly with massive power, but when they get to the cavitation speed there is a really big increase in drag. I LOT of power may allow it to be overcome to a limited extent but it is apparently a bit like hitting a brick wall of drag. So everything is working great at speeds below that threashold, and then you hit the cavitation wall, and thats pretty much IT!

They seem to sit at a pretty stead 47kts or so downwind, so I assume whilst hard to hit over 50kts (cavitation territory?), mid 40s might be well within the realms of current tech?

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Ant-man said..
Yep Im absolutely riveted by these boats and races. I wonder if windsurf sails will become adjustable double skin in the future, incredible power and versatility.
I reckon the Italians got robbed against the poms in their last race. Sailing rules are going to have to change for these and other big foiling boats. Anyone that's foiled close to the stern of a power boat or sailing craft knows of the tremendous turbulence given off under the surface. Way to dangerous for these boats to have to pull off the manoeuvre the Italians had to despite being on starboard tack.

Hopefully the Kiwis can defend the cup.

The Italians bore away by 14 degrees. Jimmy Spithill was aiming to "have a piece of them".

Yes, their efficiency is really impressive: 45kts boat speed in less than 13kts of wind .. Even if the wind is measured at approx. at 2m above sea level (guesswork) and their mainsail reach a height of 28-29m above sea..
Not to mention the massive forces on their foils,- 6500kgs of boat-weight + the power of 230sq meters of very efficient sails..

The Italians are coming..

The boats are impressive but the racing is boring.

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Ben1973 said..
The boats are impressive but the racing is boring.

I agree, so far apart from one race its been who gets in the lead keeps it pretty much. Hopefully as we get to the pointy end this will change but to be honest I think the kiwis will be too quick, they won't engage in the start box knowing they have 6 legs to mow whoever it is down.

Also, they are non traditional boats they should have changed the course layouts, tighten up some reaches for the downwind so we get to see what the boats actually do for top speeds

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cald said..

Ben1973 said..
The boats are impressive but the racing is boring.

I agree, so far apart from one race its been who gets in the lead keeps it pretty much. Hopefully as we get to the pointy end this will change but to be honest I think the kiwis will be too quick, they won't engage in the start box knowing they have 6 legs to mow whoever it is down.

Also, they are non traditional boats they should have changed the course layouts, tighten up some reaches for the downwind so we get to see what the boats actually do for top speeds

I disagree. I find the racing facinating and so much more so because of the virtual eye in the sky with all the speeds and distances superimposed on our screens.

if you are a sailing boat racer, this is absolutely top shelf.

The WHOLE skill in sailboat racing is making the best speed/VMG upwind and downwind. There is almost NO tactics or skills in reaching. That is just about pure boat speed due to design. There is nothing to be gained from tactics and skill. Its a drag race. Once the relitive speed has been established, there is no point in doing the same thing over and over and expecting a different result. THAT is boring.

With Upwind Downwind racing there are tactics, wind shifts, tacking mistakes that come into play, in this series, the delicate skills of keeping the boat on it's foils in lighter winds, and the skills to avoid crashdowns in the mannouvers, and THAT is what sailboat racing is about.

There would also be a big danger in pushing these boats for max speed. There would inevitably be big crashes when their foils cavitate and the boats slam back down in the water. They are not designed for that, however entertaining that might be for a brief moment.

It definitely begs the question of what might be possible if they could work out how to utilise supercavitating foils though, as the boats seem to have the power and speed required to work in that space. I supect it would bring engineering of the control systems to a whole new level though.

Maybe thats the challenge for the next America's Cup?

Yep, the courses are fine, racing on foils and foiling in general is best hard on the wind or bearing right away. Reaching doesn't really mean the best speeds. When reaching the loads get all over the shop, nothing more hairy than trying to nail a Moth down on the reach of death and in the struggle top speeds are not gained. A good example is what happened to AM when they broke it, they got caught reaching in a squall before they could bear away and nail the trim down, just got blown out of the water with excess windage due to a feathering rig rather than one driving the boat down on opposing foil lift, it's all about balancing the forces. So fanging off downwind will produce pretty much the top end speed you will see from these boats, love the bear away round the top mark though.

Might as well be watching a radio control boat, most of the time you don't even see the crew, the ones you do are playing on a control pad.
seeing guys on deck running around with rope everywhere, making adjustments changing sails putting spinnakers up is what make it good to watch, that plus the boats actually racing each other. This is just a drag race controlled by computers.

This is how it should be

Hi
Yes it could potentially be boring if one boat outruns its competitor each race, however the pace as which turns happen and what line is taken could change the race so there is the anticipation of one boat miscalculating one aspect and its playing catchup, so the excitement is there.

I was watching an old race of the single keel boats and of coarse that is slow but tactical as the boats are side by side one taking the wind out of the sails from the other boat constant tacks forcing the other away off coarse and the crew moving about changing ropes etc. that is hard work. So the ac75 are adrenalin fuel the single keel are anticipation anxiety races.
Either way I am enjoying the adrenalin fuel races on tv that is, live maybe not.Regards Walt

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Ben1973 said..
This is how it should be

That is as BORING as watching the grass grow1

The other most excitiong sailing race series on TV have been the 18Footers and the SailGP, simply due to the broardcast technology that enables us to view their every move and actually see the race unfold. There is no way that is possible with live viewing. This why the Olyimpics sailing is such a DUD! They just don't exploit the broadcast medium possibilities at all.

Easiest way to ensure close racing would be to one design the foils. Allow development up to 6 months out then one foil design is chosen for all boats for the racing.

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mr love said..
Easiest way to ensure close racing would be to one design the foils. Allow development up to 6 months out then one foil design is chosen for all boats for the racing.

Martin,
The foil mast is a one design with each team developing their own foil supposedly within the rules i.e. foil flaps can only pivot from one point (unlike the ailerons / flaps on a commercial airliner) although there seems to be some clever (read loopholes) interpretations of those rules.

BTW - I agree that this is incredibly exciting match racing to watch - one mistake and the lead is lost - just look at the Brits at the start yesterday when they breached pre-start. They basically handed the win to LR right there and then. Shoe would have been on other foot if LR had made a mistake pre-start or in race but have sailed faultlessly in 4 races.

Each to their own but for me this has been awesome viewing. Great camera angles, close racing (the gaps look big but that distance becomes very small at 40+ knots for most of the races), cutting edge technology, elite sailors and athletes.
I guess the question to the nay sayers is, would you prefer the older displacement style boats to be competing for the Americas Cup?

Shame it is now being delayed due to covid...

I think my point was somewhat missed with the course layout, i just want to see what the boats could do, i seem to remember with the previous cats they had a short reach to the finish line?

They basically have the ability to define what they want, they could have kept the upwind/downwind legs and added a 500m reach at the top or bottom - why not let them line up for the 500m speed records haha... and as far as danger, breaking boats etc, pls give me a break! They are constantly battling that on all points of sail now.

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Ant-man said..
Each to their own but for me this has been awesome viewing. Great camera angles, close racing (the gaps look big but that distance becomes very small at 40+ knots for most of the races), cutting edge technology, elite sailors and athletes.
I guess the question to the nay sayers is, would you prefer the older displacement style boats to be competing for the Americas Cup?

If the races are close and there is genuine tactics and lead changes perhaps, i was enthralled with it previously. Happy for the foils too if we were seeing more back and forth... these are gen1 boats if the class survives this cup and there is another i am sure it will be closer

also miss the old salty sailors yelling at each other though, that added to the theatre

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cald said..
Shame it is now being delayed due to covid...

I think my point was somewhat missed with the course layout, i just want to see what the boats could do, i seem to remember with the previous cats they had a short reach to the finish line?

They basically have the ability to define what they want, they could have kept the upwind/downwind legs and added a 500m reach at the top or bottom - why not let them line up for the 500m speed records haha... and as far as danger, breaking boats etc, pls give me a break! They are constantly battling that on all points of sail now.

I think you missed the point entirely.

This is a RACE. It is about upwind, downwind skills and tactics, and the ability to win the start. Just like every other normal sailing race. Your wish to see them push their speed limits on a reaching course will have to be satified with the the brief time they transition though that as they round the upwind mark where we have already seen some major dramas.

There really is a speed limit for these craft and it is the cavitation limit. They are getting very close to that now in some of the mark roundings, and arguably, this has been reached and caused crash downs already. They are not stupid. They know the danger of ignoring those limits. If they were building a craft for maximum speed on a reach, it would be completely different and almost certainly, the foils would be as well.