Jump to content

An extreme case of not quite getting the boat where it needs to go in a gust of wind..


DandV

Featured Posts

1 hour ago, Dr Bob said:

Iced tea with a shot of rum is nice.

One of the best cups of tea I ever had was after a rough, wet crossing of the Thames Estuary from Ramsgate. When we got in the confines of the Deben River the Skipper's wife made a pot of tea and put in a couple of shots of rum from a optic on the galley bulkhead!

  • Haha 1
Link to comment
Share on other sites

1 hour ago, nicknorman said:

Actually when I said “not really” I guess they are in fact the same thing. The only difference is that with the reaching boat, the air is coming from the side to propel it along, whereas with the glider it is coming from underneath (relatively speaking, since of course it may be that the glider that is descending rather than the air rising). Otherwise, the principle is the same which is why some boats have solid aerofoil “wings” for sails, but pointing upwards instead of sideways.

Mary Shafer of NASA Dryden has explained that it is all caused by lift demons ( and thrust pixies for powered aircraft).  There are probably aquatic sub-species too, for sailing botes.  Lift demons appreciate beauty, and will not readily go near ugly aircraft, which is why they do not fly well.

 

N

  • Greenie 2
Link to comment
Share on other sites

5 hours ago, bizzard said:

A bit like an aircrafts wing shape, the curvature of the sail. On a reach the outer convex side is pulled by the suction of the wind, the inner concave is pushed by the wind, the suction is more powerful.  I bet all the crew were reaching on that boat too.

The main is actually two sails with the two sail tracks on the outer extremities of a D shaped mast for the leading edge. Clever control lines between the sails to shape the composite, to shape the entire aero foil. They have broken 50 knots.

Patriot will miss next weekends round robin but are planning on being back in the competition a week later. Replacing, and testing the electronics is what will take the time, but all teams, and the local marine industry are making it happen.

  • Greenie 1
Link to comment
Share on other sites

  • 1 month later...

Well we are six races into the first to seven wins into the Prada cup to decide who the challenger is.

Until the second race yesterday things were all going the Italian's way.

Team GB Brittania seems neither to like light winds and going round corners, loosing ground each tack and gybe but above very light winds seemed to be able to match the straight line speed of Luna Rosa. They had never led in all the legs of all of the races until last race.

Yesterdays second race in slightly more wind, and the right jib choice this time suited Team GB better, and this rewarded them with their first well deserved win, something we all cheered for here, as each GB win prolongs the series.

On shore was not without it's controversy either, as a mystery covid case in Auckland ramped up our alert levels, initially two steps to lockdown but by the time racing began now only one step, but this one step has restrictions on gathering sizes, ruling out sailing close into the city hills and severly diminishing the commercial benifits to our  hospitality venues severly missing overseas tourists.

Team GB sided with a longer break to racing, to after the probable easing of covid level on Monday night, which would have reinstated the cup village commercial buzz, but also to next week's stronger wind forecasts. Luna Rosa understandably wanted to maintain their momentum and insisted the race be sailed in accordance with the previously agreed Covid protocols for our different alert levels.

Any way a win for the Brits has re-established the much needed competition in the series.  The boats really do impress 40knots in only 10knots of wind, leaving barely a bit of spray but barely a ripple. The races are normally about 12 nautical miles, normally accomplished in under half an hour

  • Greenie 3
Link to comment
Share on other sites

Oh no,  that was disappointing! We got whooped.

Ineos was so dominant during the round robin but I didnt believe the hype around 'Ineos have the advantage  with 2 weeks off as they have a few weeks to improve the boat'. The Italians just seem to get better and better in that final series against the US. When we got to this final then, the Italian boat just pointed a lot better - a combination of a better boat and better racing skills? How much of this is down to real race experience?

I've not a clue how the crews practice racing - they dont have a 2nd boat do they to race against? 

Overall this final series of 8 races was rather boring. The Italians were so dominant - and the only interest was the close start in the last two races. The Italian boat just seemed to point a lot higher and dominate all the upwind legs.

Lets hope the NZ/Italians final is a closer match. We were short changed with only 8 races in this one.

 

15 hours ago, DandV said:

The boats really do impress 40knots in only 10knots of wind

How on earth can a sail boat go at 40knts in 10 knts of wind? Surely that equates to perpetual motion?  I cant understand how they fly. Why dont they tip over? The sail area must create such a force pushing the mast over, yet the boat is flat above the water. Is it about controlling the weight on the windward side of the boat  to keep it level as the foil in the water cant exert much in the way of stopping the boat tipping - can it? I can see how foils lift small boats like moths....but these AC75s? Its a tiny foil compared to the boat size. There must be some huge forces on the foil and its support.

 

So when NZ win it, what sort of 'boat' will they choose for the next one?

Link to comment
Share on other sites

 

6 hours ago, Dr Bob said:

Oh no,  that was disappointing! 

 

How on earth can a sail boat go at 40knts in 10 knts of wind? Surely that equates to perpetual motion?  I cant understand how they fly. Why dont they tip over? The sail area must create such a force pushing the mast over, yet the boat is flat above the water. Is it about controlling the weight on the windward side of the boat  to keep it level as the foil in the water cant exert much in the way of stopping the boat tipping - can it? I can see how foils lift small boats like moths....but these AC75s? Its a tiny foil compared to the boat size. There must be some huge forces on the foil and its support.

 

So when NZ win it, what sort of 'boat' will they choose for the next one?

I agree the mismatch of boat speed in the lightish conditions made for a disappointing competition.

But the competition is about design innovation as well as crew work.

The speed of the boats is by using the leveraging effect of sailing largely back and forward across the true wind direction, bit like tha amplification of downwards pressure employed by screw threads. Because their forward speed generates it's own headwind, the boats are always sailed so incredibly close hauled.

The overturning moment is  countered by asymmetric movement of the control surfaces of the foils, and the ballast incorporated in the foils, which becomes even more effective when the windward foil is raised clear of the water, like a bunch of crew out on the trapeze.

Apart from some blazers in the board room of the New York Yacht Club who want to return to "traditional monohull keelers" I don't think there is much appetite anywhere else to change the class of boat for the next cup.

The current sailors love them, and they have really caught the imagination of the next generation of sailors on their foiling sailboats and foiling moths. 

The races are short enough to fit between ad breaks on commercial television, important for promotion and income.

And they have proved to be safer then catamarans with their propensity to pitch pole.

They also have a wider sailable wind envelope.

 

  • Greenie 1
Link to comment
Share on other sites

3 minutes ago, DandV said:

and the ballast incorporated in the foils, which becomes even more effective when the windward foil is raised clear of the water, like a bunch of crew out on the trapeze.

Ah, I had missed that one. Of course. I wondered where the weight was on the windward side. I guess the foils can be very heavy.

 

How have the NZ team been practising? Are they out everyday on a practice course? I wouldnt like one of those winging past me on an afternoon cruise with the family.

Link to comment
Share on other sites

16 minutes ago, Dr Bob said:

Ah, I had missed that one. Of course. I wondered where the weight was on the windward side. I guess the foils can be very heavy.

 

How have the NZ team been practising? Are they out everyday on a practice course? I wouldnt like one of those winging past me on an afternoon cruise with the family.

Weight at the bottom of the foil arms is the only place where weight is an advantage. Overall weight of the boats is included in the design regs.

Team NZ practice on the various courses, as defender they had access to the course before and after the races in the challenger series to bracket the conditions of the challenger races to assess their own performance. Pre start scenarios are played out in practice against a chase boat with it's four 300HP outboards or on the simulator 

This was the technique they used for their Bermuda challenge when their minimal budget precluded their arrival in Bermuda to the last minute. But it also meant they arrived in Bermuda very much the unknown quantity, even to themselves!

The challenger is disadvantaged by the lack of actual racing before the cup, a disadvantage that was reinstated for this challenge, after being negated by Oracle for the last challenge when their boat joined the Challenger series and they even carried a one race advantage into the actual America's Cup, from their series win in all pre cup regattas.

Link to comment
Share on other sites

  • 2 weeks later...

A photo that I think dramatically shows how little water disturbance these boats make, at near 50knots.

From today's NZ Herald

The full article here saying 60knots though is "just dreaming"

https://www.nzherald.co.nz/sport/americas-cup-2021-team-new-zealand-skipper-glenn-ashby-talks-down-speed-rumour/J7UJDEV2QYD3E2GX3ETMIRDPNU/

SQFELN2HR4OQDBI6PMZSDTEUIA.jpg

Edited by DandV
  • Greenie 1
Link to comment
Share on other sites

I thought the photo looked like the windward foils have been swivelled to lie parallel to the hull. But no, just that the foil had been photographed end on.

Edited by DandV
Mis interpretation of photo
Link to comment
Share on other sites

On 04/03/2021 at 07:11, tree monkey said:

Don't get all technical I think that's all smoke and mirrors to hide the fact it's witchcraft.

 

"Any sufficiently advanced technology is indistinguishable from witchcraft" -- Arthur C Clarke, with a sex change ?

  • Greenie 1
Link to comment
Share on other sites

5 hours to the first race of the actual Americas Cup. 2 races scheduled today, then a day off before racing recommences with two races per day, without break,  until one contestant books seven wins. Wind conditions permitting of course.

Forecast is currently 10knots rising to 15knots this afternoon. So mid range. 

Unfortunately because Auckland is still under level 2 covid restrictions precluding gatherings of over 100 people they are using an outer racing course rather then the inner course under North Head and Bastion Point vantage points. So I will watch on the TV.

Hopefully it all goes well with the local team. The big silver cup looks great above the prize giving for our classic yachting fleet.

Edited by DandV
Link to comment
Share on other sites

2 days, and four races of racing now accomplished both at the lower end of the allowed wind strength that plays into the Italians particular strength.

Results are two all, with he who wins the start wins the race, so we have a real competition on our hands. Forecast for the next days of racing is more light winds.

Auckland now back to lowest covid alert level with more then a week free of community transmission. This means the more challenging inshore course can be used as the restraint on spectator assembly numbers has been removed, and we can party up large.

Spoke to a former neighbour who had his first covid vaccine two days ago as the partner of a worker at one of the managed isolation hotels so the program is underway starting with bolstering border protection.

 

Link to comment
Share on other sites

Since my  last post we have had two days of racing and  one day when the wind did not meet then liwe threshold of 6.5 knots over the 5 minutes before race start.

The first day of actual racing continued the trend as to who won the start in light conditions could finish first.

But the winning margins were much tighter when Team NZ was behind, indicating perhaps they had a faster boat, but not fast enough to overtake the advantage of being in front. So racing tied 3 all out of seven to win.

The next day racing abandoned as not enough wind.

Today first race start at about 8 knots wind rising Team NZ was was initially disadvantaged by smaller foils and smaller job (harder to keep aloft but less drag when speed  builds) so lost the start but a building wind meant the first lead change in the whole regatta with Team NZ cementing a convincing win.

The second race was in lightening winds so the imperative of keeping the boat aloft on foils, and more brilliant helming with the bigger foils and jib of Italians saw them lead off but superior  boat speed kept the kiwis in touch and challenging, until a challenging gybe put Team NZ through it's own wind shadow and off it's foils just watching the Italians  build a 2km 4 minute lead until a little more wind got them up on their foils. Then disaster for the Italians as a soft wind patch on their last mark rounding saw them fall off their foils watching as  the now foiling Team NZ sailed right past and change places, 2km and 4minute advantage turn into a cruel 8 minute deficit before they regained foiling.

So now after a bizarre day of racing it is 5 to 3 in NZ's favour in a first to seven wins series.

Great contest.

 

 

Link to comment
Share on other sites

Never seen anything like these before, they're King Awesome!

 

I suppose a narrowboat would need much bigger foils ?‍♂️ to get enough lift...  and they would be torn off at the first bridge'ole. :banghead:

Ah well, I can stick to 4mph.

Link to comment
Share on other sites

11 minutes ago, wakey_wake said:

Never seen anything like these before, they're King Awesome!

 

I suppose a narrowboat would need much bigger foils ?‍♂️ to get enough lift...  and they would be torn off at the first bridge'ole. :banghead:

Ah well, I can stick to 4mph.

A narrowboat is a wonderful way of staying close to the real world and staying clear of any sort of race. Rat race and all. Continue to enjoy your boating  and stay clear of foils, tin foil, and otherwise.

But watching those Am Cup boats racing, is a wonderful escape from  our normal realities!

  • Greenie 1
Link to comment
Share on other sites

1 hour ago, wakey_wake said:

Never seen anything like these before, they're King Awesome!

 

I suppose a narrowboat would need much bigger foils ?‍♂️ to get enough lift...  and they would be torn off at the first bridge'ole. :banghead:

Ah well, I can stick to 4mph.

 

You will definately upset a lot of people if you stick to 4mph when passing their badly moored boats... ????

Edited by cuthound
To insert a missing space
Link to comment
Share on other sites

The racing continues with wind conditions making only one race possible today after an even start, Prada with an ability to sail higher, and superb "elbows out wide", sailing forced the otherwise faster Team NZ boat to follow around the course until just before the final mark rounding a big wind shift under the lee  of the volcanic cone of North Head, decisively favoured Team NZ who stormed home to a comfortable lead. So one win now required for Team NZ against 4 required for Prada. 

Strong indications are if Team NZ wins, that the next "Challenger of Record" will be the Royal Yacht Squadron of Cowes, the sponsoring club for Team GB in this last challenge. 

The current class of boats of foiling monohulls will be retained. It also appears that nationality rules of sailors will be further tightened after the Oracle American defences used to be sailed with only one or two Americans onboard.

But Team NZ is asking for competing hosting bids from cities around the world to try and extract more money from the NZ Government and Auckland Council.

They have to be careful though, by a similar process Auckland lost for some years, the mid race hosting rights for the Whitbread, now Volvo round the world stopover, but the event suffered, and therefore sponsorship declined without the Auckland spectacle of mass greeting of arrival and departure of the fleet. Stopovers are now restored to Auckland with minimal public funding. Perhaps the next Am Cup will be sailed, like the first on the Solent,  if Boris coughs up enough?

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.