Wow, its come along way since Bondy and co. Hope there is some close racing

That is amazing, I like the curved keel design, I guess they slide up and down depending on direction.

doggie said...

That is amazing, I like the curved keel design, I guess they slide up and down depending on direction.

Yes, they do slide up and down. They're "centerboards", as distinct from a "keel" - there's no heavy weight on the ends. I suspect that there's a little "artistic licence" happening there also. I think they should probably curve the other way, so that as the boat "leans" (flies a hull) the leeward centerboard would become more vertical in the water, thus enhancing its effectiveness. As they're shown their effectiveness would reduce as the boat leans. It's a clever idea to curve the centre boards though. A bit like the swing keels being used on ocean racing yachts - viz: Volvo70, only different .

busterwa said...
so what are the principles of that twin hull yacht?

Does one side anchor in the "rail of the boat" and the other sheet in as much as possible until there out of the water! They use rachets to pull the sail in?
Im a windsurfer and probally never even get to go on a boats like that unless i win lotto .. twice ;-)

It's primarily a matter of levers. The leeward hull provides the fulcrum, the sail the load and the crew etc on the windward hull providing the effort. So you can cope with more wind and still keep the whole shebang upright. There are other bonuses too, such as considerably reduced drag in the water and considerably reduced overall weight. Also. I'm quite sure that as the leeward hull buries into the water it acts like the rail on your board, to stop you from simply drifting sidewards (in conjunction with the centreboard).

Sail trim is done by ratcheted winches, but that's just a requirement due to the huge loads involved. Small dinghys might have a ratchet block to help the crew hold the weight on the sheet, but as the sails/loads get bigger a winch is required. I think there's some rule disallowing motorized winches for racing yachts, but I know they're available for cruising yachts.

busterwa said...
I think it would be a pretty skilled technical sport to do.To get a boat like that really humming would be a rush.

Yes, I certainly agree there. Having sailed small boats, at quite a high level for many years, and knowing the rush there, I reckon it would be an adrenaline rush to easily rival windsurfing. The blokes who sail these things at that level are elite athletes in any company.

Can't wait to see one of these things in the flesh, sailing. Btw, the AC45 is the America's Cup 45 (feet long) and the AC72 is the America's Cup 72 (feet long) - they're big boats!

is that the thing that was cartwheeling and pitch poling across San Francisco Harbour yesterday with crew flying in all directions ?.....

Richiefish said...

is that the thing that was cartwheeling and pitch poling across San Francisco Harbour yesterday with crew flying in all directions ?.....

I wouldn't doubt it. Sailing one of those things would be as dangerous as any other elite sport. I'm sure that sailing either an AC45 or an AC72 would be razor's edge stuff.

If you come across a bonafide news item about that I'd love to see it.

EDIT: Found it!
www.dailymail.co.uk/news/article-2003314/Crew-sent-flying-new-catamaran-cartwheels-sea-San-Francisco-Bay.html

MORE EDIT: From the article:
"Competitors will use the new catamarans in 2011-2012 Americas Cup World Series starting in Cascais, Portugal, in August.

Larger 72ft AC72 catamarans, which have yet to be built, will be raced in the competition the following year in San Francisco."

The "Americas Cup World Series", btw is not the "America's Cup"

I always thought sailing was one of those sports that's deadly tedious to watch on telly but good fun to do. Like motorcycle racing and sex( though come to think of it watching sex on telly isn't that bad).

preview this

Slightly relevant. Sailing scene from the 99 version of "The Thomas Crown Affair".

choco said...

preview this

That was an expensive crash, hows the guy falling through the sail/wing!!

byf said...

They interviewed the guy that went through the sail on the news last night doggie and he reckons if he didnt have his helmet on it may have been much worse as he went through it head first.

Just from that footage they were very lucky that no one was hurt badly, are those wings made from carbon and kevlar? They would cut you badly I would expect

CJW said...
They are curved that way because they are 'foiling' centre boards, that is, they create a large vertical lift component when sailing, massively reducing the wetted surface drag on the hulls, which is what it's all about. They curve inwards so as heel increases so does the lift and tangential force decreases, which makes the boat easier to control in high heel angles. If you curve them the other way lift decreases with heel but the tangential force increases, making it fairly sketchy as you increase heel angle.

That's very clever indeed. I did think that they might be foils, but obviously the whole boat doesn't lift out of the water on them, there being only 1 each side. I can see how they would reduce drag a huge amount. Can't wait to see them sailing.