Whoohoo, it’s America’s Cup time again!

[Zimmerframe]

Waiting for a comment from @Mikerb to this thread. Maybe he is actually racing in it ?

He needs to upgrade first ...

 

[steve_sordy]

How they get up to 49.1 knots boat speed from just 12 knots of breeze is beyond me!

Because they sail at an angle to the wind. They use the force from the wind on a huge sail and a very low friction hull and away they go. When I used to windsurf in the 1970's I frequently went faster than the wind. And that was old tech!

PS: I still have that Sea Panther sailboard if anybody wants it, free to a good home, comes with two sails (main and storm) and two daggerboards, main and storm.

 

[GrandPaBrogan]

Because they sail at an angle to the wind. They use the force from the wind on a huge sail and a very low friction hull and away they go. When I used to windsurf in the 1970's I frequently went faster than the wind. And that was old tech!

I have heard similar explanations but my engineering mind keeps betraying me. Say I was pushing you sitting on your coasting bike on level ground and I was walking at 5 kph, how could you be travelling at 20 kph? And if I was walking at a 45 degree angle off to your side, surely your travel speed would be negated to less than my pushing speed.

I know I know, don’t answer my silly ‘off the cuff’ hypothesis. It just makes me laugh that the unique physics of sailing allows sailboats to even travel UPWIND (aided by tacking manoeuvres). ?

 

[paul-g]

I have heard similar explanations but my engineering mind keeps betraying me. Say I was pushing you sitting on your coasting bike on level ground and I was walking at 5 kph, how could you be travelling at 20 kph? And if I was walking at a 45 degree angle off to your side, surely your travel speed would be negated to less than my pushing speed.

I know I know, don’t answer my silly ‘off the cuff’ hypothesis. It just makes me laugh that the unique physics of sailing allows sailboats to even travel UPWIND (aided by tacking manoeuvres). ?

gramps all to do with angle of attack, windspeed and size of sail and
friction
say you had a 5mph wind a sail on the bike which harnesses the wind
and the sail was 5m in area this would generate quite a large force
especially if the angle of the sail was perfect to the wind and i would
have thought it would propel you faster than 5mph

 

[GrandPaBrogan]

gramps all to do with angle of attack, windspeed and size of sail and
friction
say you had a 5mph wind a sail on the bike which harnesses the wind
and the sail was 5m in area this would generate quite a large force
especially if the angle of the sail was perfect to the wind and i would
have thought it would propel you faster than 5mph

Yep. Point on point loading is quite different from the dynamics of sail area - and pressure differentials generated by the aerofoil shapes of sails.

 

[Mikerb]

Waiting for a comment from @Mikerb to this thread. Maybe he is actually racing in it ?

OK.........these craft are impressive but for me once you completely lose contact with the water it is something very different to sailing. Foiling has become quite popular with windsurfers but the same thing applies and outside of the pros I can get planing at just a bout the same low wind threshold as most of the foilers. In terms of speed, guys on slalom kit ( something I left behind a few years back) regularly hit speeds in excess of 30knots. Even on the freeride kit I use now it is relatively normal to hit max speeds of c 25kts with a 6.5m sail.
As mentioned above it is the force of the wind that is converted to forward motion by a sail in combination with a fin. That force is rarely constant and also varies in direction but the total force is not just dictated by wind speed since density of the air also plays a part. The forward motion of a yacht or windsurf board changes the vector of that force and increases it. At that stage what controls the forward speed is drag and that is where the foiling craft win since most of the drag is the contact between hull and the water especially in anything other than glassy seas. The sail also produces drag but the sails on the AC boats are hugely efficient ( and eye wateringly expensive!). The benefits of foiling for speed are moderated by the fact that the set up is not stable. In AC boats all aspects of the boats settings are computer controlled and that mitigates the control issues. In windsurfing with a foil there is of course no computer and terminal damage is not unusual!!

 

[GrandPaBrogan]

Exciting win for Team NZ today... a real nail biter against Luna Rossa where the lead went back and forth mainly because of light winds causing errors of dropping the boat onto the water and then struggling to get them back up onto the foils. Italian and kiwi crowds screaming at the AC village back on shore.

On high winds, errors seem to be the opposite where the boats tend to take off into the air. So the TV commentators, the spectators, and the racing teams seem to be learning unprecedented things together as the crews push the boundaries. Watching the teams acquire new skills each day makes for exciting racing.

For some reason, I missed this video about a month ago when the boats were first unveiled and set out for practice sessions. So it's not just Team NZ that likes to take airborne excursions!

The video below explains what's so different about these boats... the dynamics which requires the crew to master operating these speed rockets at the very verge of a peculiar if not spectacular 'racers edge.'
(Hope you can view this one @Zimmerframe )

 

[Pdoz]

View attachment 47621





The video below explains what's so different about these boats... the dynamics which requires the crew to master operating these speed rockets at the very verge of a peculiar if not spectacular 'racers edge.'
(Hope you can view this one @Zimmerframe )

Any idea what's going on with the leech in that first image?

Leech – The aft (back) edge of a fore-and-aft sail is called the leech (also spelled leach). The leech is either side edge of a symmetrical sail—triangular or square.

 

[GrandPaBrogan]

Any idea what's going on with the leech in that first image?

Leech – The aft (back) edge of a fore-and-aft sail is called the leech (also spelled leach). The leech is either side edge of a symmetrical sail—triangular or square.

I think it's just an optical illusion between the two sails from the angle of the screen capture. The video shows the entire movement.

 

[steve_sordy]

I have heard similar explanations but my engineering mind keeps betraying me. Say I was pushing you sitting on your coasting bike on level ground and I was walking at 5 kph, how could you be travelling at 20 kph? And if I was walking at a 45 degree angle off to your side, surely your travel speed would be negated to less than my pushing speed.

I know I know, don’t answer my silly ‘off the cuff’ hypothesis. It just makes me laugh that the unique physics of sailing allows sailboats to even travel UPWIND (aided by tacking manoeuvres). ?

A different way to think about it is a weight hanging from the middle of a rope stretched across a wide gap. The shallower the angle of the rope, the larger the tension in the rope.

Incidentally, using the same principle is how trees can be ripped from the ground by man power alone. In that case, the tree is one of the anchor points, the other anchor point is something that is NOT going to move. The weight in the middle of the rope is replaced by people pulling. The shallow angle of the ropes increases the tension in them and rips the tree from the ground.

PS: Obviously the sailboat cannot sail directly into the wind. When I was learning how to do it, at first I was so slow in the tacking manoeuvre that in stronger winds, any headway I gained was lost while I was changing tack.

 

[paul-g]

A different way to think about it is a weight hanging from the middle of a rope stretched across a wide gap. The shallower the angle of the rope, the larger the tension in the rope.

Incidentally, using the same principle is how trees can be ripped from the ground by man power alone. In that case, the tree is one of the anchor points, the other anchor point is something that is NOT going to move. The weight in the middle of the rope is replaced by people pulling. The shallow angle of the ropes increases the tension in them and rips the tree from the ground.

PS: Obviously the sailboat cannot sail directly into the wind. When I was learning how to do it, at first I was so slow in the tacking manoeuvre that in stronger winds, any headway I gained was lost while I was changing tack.

back in the 90s i had a Fanatic Cat race board all carbon a big big skeg and a huge dagger board this linked up with a (at that time)Tushingham camber induced sail got you as close to the wind as you could get and tacking very fast, Fanatic improved the board with
the Cat 2 which could rail a lot better

 

[steve_sordy]

back in the 90s i had a Fanatic Cat race board all carbon a big big skeg and a huge dagger board this linked up with a (at that time)Tushingham camber induced sail got you as close to the wind as you could get and tacking very fast, Fanatic improved the board with
the Cat 2 which could rail a lot better

I was a sailboard fanatic from the first time I saw one in Oct'77 at my local lake. I signed up for lessons, rented a wetsuit and away I went. I bought the Sea Panther in Oct'78 and I used it three times per week on club races, local competitions, holidays etc. The only thing that stopped me was dead calm, but even then I practiced my swan flapping! Then in 1986 I got ill and that was the end of that. It was one of those childhood diseases that kids shrug off but have a devastating impact upon adults. Five years later, when I had fully recovered, I didn't want to do it anymore. The board and all its kit has been in my garage since early '86. I don't fit the wetsuit anymore!

I had another go at sailboarding when in the Caribbean in 2006, but although I knew what to do, my body couldn't deliver! The local instructor/boat driver/whatever told me that "I could tell that you used to know what you were doing"

I very much suppose that my Sea Panther is now a museum piece. But it's in good nick and it seems a shame to take it to the tip. I wonder if a local club might take it for training purposes? Hmm, that has set me thinking.....

 

[paul-g]

I was a sailboard fanatic from the first time I saw one in Oct'77 at my local lake. I signed up for lessons, rented a wetsuit and away I went. I bought the Sea Panther in Oct'78 and I used it three times per week on club races, local competitions, holidays etc. The only thing that stopped me was dead calm, but even then I practiced my swan flapping! Then in 1986 I got ill and that was the end of that. It was one of those childhood diseases that kids shrug off but have a devastating impact upon adults. Five years later, when I had fully recovered, I didn't want to do it anymore. The board and all its kit has been in my garage since early '86. I don't fit the wetsuit anymore!

I had another go at sailboarding when in the Caribbean in 2006, but although I knew what to do, my body couldn't deliver! The local instructor/boat driver/whatever told me that "I could tell that you used to know what you were doing"

I very much suppose that my Sea Panther is now a museum piece. But it's in good nick and it seems a shame to take it to the tip. I wonder if a local club might take it for training purposes? Hmm, that has set me thinking.....

don`t tell me Rother Valley?
was terrible for shadows, wind wasn`t constant at all

 

[steve_sordy]

don`t tell me Rother Valley?
was terrible for shadows, wind wasn`t constant at all

No, I learned at Ferry Meadows Country Park in Peterborough. It was a 70 acre lake, so even in the fiercest winds you never got really big waves. According to the anemometer on the clubhouse roof I went out once in wind speed of 63knots. I had borrowed a 2.6m2 storm sail. and I had fitted my home made storm dagger-board. I launched in the wind shadow of the clubhouse and then holy hell was unleashed. I shot to the end of the lake at warp speed and then had to be rescued. The wind was just too strong for me to turn and tack. I got a big thumbs up from the club captain though! I've got some photos somewhere, not digital though.

 

[paul-g]

No, I learned at Ferry Meadows Country Park in Peterborough. It was a 70 acre lake, so even in the fiercest winds you never got really big waves. According to the anemometer on the clubhouse roof I went out once in wind speed of 63knots. I had borrowed a 2.6m2 storm sail. and I had fitted my home made storm dagger-board. I launched in the wind shadow of the clubhouse and then holy hell was unleashed. I shot to the end of the lake at warp speed and then had to be rescued. The wind was just too strong for me to turn and tack. I got a big thumbs up from the club captain though! I've got some photos somewhere, not digital though.

nice anecdote
we always liked when we could (due to wife ex, kids at that time) get to south shore at Brid.
this one day four of us sailed in a force 4 cross off with varying degrees of difficulty trying to
get back to shore, 1 plonker put up a 6m on a long board and nearly the last i saw of him was
heading towards Sweden at about 30mph.private boat had to get him. good days

 

[paul-g]

nice anecdote
we always liked when we could (due to wife ex, kids at that time) get to south shore at Brid.
this one day four of us sailed in a force 4 cross off with varying degrees of difficulty trying to
get back to shore, 1 plonker put up a 6m on a long board and nearly the last i saw of him was
heading towards Sweden at about 30mph.private boat had to get him. good days

then water starting damaged the back, and by by to windsurfing.to think about it we were all as mad as these guys
with the things we used to get upto

 

[Zimmerframe]

The board and all its kit has been in my garage since early '86. I don't fit the wetsuit anymore!

Neoprene is well known for shrinking ... so don't worry about that ...

Your board sounds like it would make a really cool outdoor bar top ! Hell, it's light (ish) it could be a mobile light ish bar top .. or send it to @dobbyhasfriends to be turned into a strong yet portable ramp !

Send it to @Rob Rides EMTB to be painted Purple and used as the next confusing EMTB back drop on youtube ...

Or a cool garden swing - you even have a mast as a top pole.. Or go lazy hammock , cut it in half, pole along the top of the two upright halves, hammock from the sail .. Wetsuit cut up and turned into wine bottle coolers. Maybe bin the groin area - or sell it on e-bay.

Or send it to @BAMBAMODA so he can dress up and play point break and look sexy for the ladies in the woods, his present technique of sitting there all night saying "can I put my sausage in your bbq" isn't working. Or even "Kann ich meine Wurst in Ihren Grill legen ?"

 

[Zimmerframe]

In terms of overview of what the boats can do, the rules, the designs, the technology, this video's the best overall I've seen for not too long :


I can't quite imagine what it must be like maintaining 50 knots in a sail boat .. ! Balanced on a knife edge ..

 

[GrandPaBrogan]

When I first saw the CGI proposal years ago I thought the concept was too weird. Didn’t pay too much attention about it until now.

It’s a huge commitment to build something like that at great cost - just straight out of CAD simulations. Not surprised only a few teams went for it, but I was sceptical too.

Now if only the crew can lay off the baked beans!

 

[paul-g]

When I first saw the CGI proposal years ago I thought the concept was too weird. Didn’t pay too much attention about it until now.

It’s a huge commitment to build something like that at great cost - just straight out of CAD simulations. Not surprised only a few teams went for it, but I was sceptical too.

Now if only the crew can lay off the baked beans!

mind boggling the stresses that must be on those er er flippers
think Robs bike should be ok then

 

[Zimmerframe]

mind boggling the stresses that must be on those er er flippers
think Robs bike should be ok then

At risk of sounding political .. each time they lift from the water .. shall we call them a brexit ?

 

[paul-g]

At risk of sounding political .. each time they lift from the water .. shall we call them a brexit ?

only if your network signal is still blocked and you can`t view
the videos

 

[GrandPaBrogan]

mind boggling the stresses that must be on those er er flippers
think Robs bike should be ok then

Imagine if those foils were actually made in China? ?

At risk of sounding political .. each time they lift from the water .. shall we call them a brexit ?

How about I push it even further and call it VirtueXenoHydroPhobia? ?

 

[paul-g]

Imagine if those foils were actually made in China? ?


How about I push it even further and call it VirtueXenoHydroPhobia? ?

what the f..ks that ? water up the ass

 

[steve_sordy]

what the f..ks that ? water up the ass

No, Alien (Xeno) water (Hydro) up the arse (Phobia), in church! (Virtue)

 

[Zimmerframe]

No Alien (Xeno) water (Hydro) up the arse (Phobia), in church! (Virtue)

You can't say that .. this is a public , @Christian , forum ...

 

[Zimmerframe]

I'm pretty sure in the game of forum that @GrandPaBrogan wouldn't have expected Yacht - would become arse in only 58 moves.

 

[GrandPaBrogan]

I'm pretty sure in the game of forum that @GrandPaBrogan wouldn't have expected Yacht - would become arse in only 58 moves.

With you around Zimbo, I’m surprised it’s taken this long ??

 

[Mikerb]

Windsurf world speed record is 53.27kts and you can buy the same kit for about £5k so you dont have to spend a fortune to go fast!!
I have windsurfed for about 35 years having sailed dinghies before discovering the sport. I live on the south coast ( UK) only 2 miles from the sea so have the choice of loads of beaches close by. There is absolutely nothing else I have tried.....including MTB!.... that compares to the sensation of planing at full tilt driven only by the wind and pitching your wits and skill against whatever the elements can throw at you.....often with no view of shore and no one else around. It cleanses the soul!!

 

[Zimmerframe]

I know the fastest I've been on water is just a shade under 90mph (GPS) when I was younger and even more stupid on a Phantom 21 with a Mercury XR2 hanging off the back. It was a b1tch to setup with props for top end depending on water conditions but one freezing new years morning, it was perfect. Terrifying might be more correct than perfect , I think I once read that water speed feels like 3 times land speed, I have no idea how I didn't lose my eye brows that day.

I still think from my time on sail boats, that 50 knots on one of the AC75's would feel like a whole different league of nuts ... I know it's slower, but it's even more at the mercy of the earth. Somehow that just makes it scarier ?!

But then I can't even imagine 53 kts on a windsurfer, so I guess it's all relative.

I'm going to fall out of bed tonight aren't I.