Jump to content

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


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!

Link to post
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 post
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 post
Share on other sites
10 hours ago, matty40s said:

Go to about 2.46 to see the capsize.

 

The aerial shots when you can compare the was from the power boats following compared to next to nothing from the foils 

Link to post
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 post
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 post
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 post
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 post
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 post
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.