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Old 29-09-2019, 06:36   #31
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Re: catamaran flipped in Auckland tornado

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Originally Posted by a64pilot View Post
Now this is not an attempt to beat on a Cat, but I think they are subject to a form of compression lift with the two hills and bridge deck.
https://en.m.wikipedia.org/wiki/Compression_lift

Think pickle fork tunnel hull too.
Why do we all feel like we have to state "this is not an attempt to pick on a cat " or "I like cats".
A cat went flying through the air literally, that's discussion worthy.

Actually best no one answers , it will obviously be inflammatory.
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Old 29-09-2019, 06:39   #32
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Re: catamaran flipped in Auckland tornado

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Originally Posted by daletournier View Post
Why do we all feel like we have to state "this is not an attempt to pick on a cat " or "I like cats".
A cat went flying through the air literally, that's discussion worthy.

Actually best no one answers , it will obviously be inflammatory.
I owe you an email, sorry!!! I've been a bit rubbish, got a bit going on at the moment. I'll reply in the next 24 hours
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Old 29-09-2019, 06:56   #33
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Re: catamaran flipped in Auckland tornado

Would this have happened to a fully loaded 30t Lagoon 52?


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Old 29-09-2019, 07:25   #34
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Re: catamaran flipped in Auckland tornado

What does a Jumbo jet weight and what is the take off speed? 160kn for a fully loaded 747 at 447t. A 52 lagoon of 30t is lightweight and may need a shorter runway in the right conditions.

What was the wind speed of the tornado?
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Old 29-09-2019, 07:51   #35
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Re: catamaran flipped in Auckland tornado

I can't find a video right now but I'm sure others here have seen when planes are actually tied to the tarmac at the airport during a storm and the nose actually lifts up off the ground in this stationary position.
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Old 29-09-2019, 08:01   #36
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Re: catamaran flipped in Auckland tornado

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Originally Posted by a64pilot View Post
Now this is not an attempt to beat on a Cat, but I think they are subject to a form of compression lift with the two hulls and bridge deck, but ground effect from the waters surface would greatly enhance the lift.
https://en.m.wikipedia.org/wiki/Compression_lift

Think pickle fork tunnel hull.

I think this is a misconception.......... Have you heard of the Bernoulli effect? The curved underside of front edge of the bridge deck will accelerate the air flow through the space underneath creating a venturi and dropping the pressure........... They used to make a device called a carburetor for supplying fuel to engines before the day of fuel injection that used this principle, and aircraft wings have been said to use this to create lift by reducing pressure above the leading edge.... though the latest narrative has a bit more complex explanation.

This is counter intuitive.... but it is used in all kinds of applications



Bernoulli's principle

Venturi effect
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Old 29-09-2019, 18:01   #37
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Re: catamaran flipped in Auckland tornado

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Originally Posted by owly View Post
I think this is a misconception.......... Have you heard of the Bernoulli effect? The curved underside of front edge of the bridge deck will accelerate the air flow through the space underneath creating a venturi and dropping the pressure........... They used to make a device called a carburetor for supplying fuel to engines before the day of fuel injection that used this principle, and aircraft wings have been said to use this to create lift by reducing pressure above the leading edge.... though the latest narrative has a bit more complex explanation.

This is counter intuitive.... but it is used in all kinds of applications



Bernoulli's principle

Venturi effect
Wow, maybe I need to turn my cat over and put the mast on the bridge deck.
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Old 29-09-2019, 22:45   #38
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Re: catamaran flipped in Auckland tornado

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Originally Posted by daletournier View Post
Why do we all feel like we have to state "this is not an attempt to pick on a cat " or "I like cats".
A cat went flying through the air literally, that's discussion worthy.

Actually best no one answers , it will obviously be inflammatory.
Why do people feel the need to post at all, when they have nothing to contribute?

It's just forums.
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Old 30-09-2019, 00:02   #39
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Re: catamaran flipped in Auckland tornado

This event reminder me of A conversation I had with Lock Crowther many years ago was about the lift experienced by cats in high winds. Cats that have sloping front windows that transition into cabintops and hard bimini tops he thought were particularly vulnerable, acting like the top surface of a wing.

Lock recommended taking off a door and strapping across the front of the mast, in order to create as much turbulence on the upper surface as possible. He said he'd had a clients boat lift out of the water at anchor in the lagoon at New Caledonia, which got him thinking of the door trick.


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Old 30-09-2019, 01:03   #40
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Re: catamaran flipped in Auckland tornado

as well as the superyacht flattened in the same event note that a smaller (possibly 26-32' ish) mono was sucked up out of the water and up onto the cabin top of the next door boat.
That video is amazing though!
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Old 30-09-2019, 21:08   #41
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Re: catamaran flipped in Auckland tornado

I don't tend to superstition but Rosella hasn't had what you'd call a lucky history.

She was on the hardstand next to us several years ago and we got talking to one of her owners.

She was originally built by a group of about a half dozen friends. By the she was completed only two of them were still alive, and neither felt physically able to sail her. She was for sale, virtually unused.

And now this.
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Old 01-10-2019, 08:44   #42
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Re: catamaran flipped in Auckland tornado

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Holy Shizzle Stick Batman! Mother Nature taking revenge on Colonials for bad karma engendered against native inhabitants. Wifey and I just watched a movie last night in Berkeley called Nightingale. It is awful what European stock did to native peoples all over the planet. God, we were ugly mean sons of bitche$.
The heart of man Is the same no matter what color skin. Europe had more tech, if someone else has the tech, the same would have been done in reverse. There is no special evil by race. Historically the strong concour the weak. Sad but true.
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Old 01-10-2019, 19:12   #43
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Re: catamaran flipped in Auckland tornado

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The heart of man Is the same no matter what color skin.
Well that's definitely not true. A bit of apologism going on there. What they did wasn't ok, no matter the spin.
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