Rogue Waves - new research support

[James Marinero]

We mariners always knew that rogue waves were a reality, but scientific support was harder to come by until data started accumulating from offshore oil platforms. The Aghulas Bank off South Africa is a particularly notorious area. I usually route around seamounts when weather/sea is bad - eg off SW Portugal. Now, research is indicating that currents trigger rogue waves. No surprises there then!

Full story at rogue waves Physicsworld

Just looks to me like wind against tide (ie current) conditions on oceanic scale.

 

[Monique]

Very reasonable conclusion.

Goes hand in hand with confused seas in shallows with wind against established seas..

 

[binch]

Waves

I once navigated a frigate charged with spending a month in the North Atlantic winter measuring waves and their changing characteristics. (it was top secret, being concerned with A/s detection) I hope it isn't still top secret otherwise the dogs of war will arrive and cart me off to the tower.
One of our most scientific instruments were milk bottles half full of liquid jelly. Lowered under a buoy, we could detect something or other from the way the jelly set. (We had oceanographers on board, very earnest young men with beards.)
So far as I could tell, every conclusion reached was already enshrined in old sailors' folk-lore.
Such as:-
2% of waves are twice the height of the lowest, for example equates to the old adage that the seventh seventh is a *******. which illiterate sailors have known for centuries.
Why wont scientists believe what observant craftsmen tell them?

 

[James Marinero]

A much wider argument

Why wont scientists believe what observant craftsmen tell them?

I agree. Closed minds are dangerous. I was once an earnest young oceanographer withe a beard. Still have an open mind though, still earnest, no beard!

What flavour jelly was it?

 

[Deleted member 36384]

.... Why wont scientists believe what observant craftsmen tell them?

Because they would not be Scientists if they took it on faith. Watch you dont sail off the edge of the world.

 

[savageseadog]

Sea wave height can be modelled with Schrodinger's wave equation which was used for modelling sub atomic particles. The interesting bit is that the output of a Schrodinger model is a probablilty which means that a wave of any height is theoretically possible, just less likely than "lesser" waves. Throw in a bit of chaos theory.............

 

[KellysEye]

I worked with a Cambridge graduate who had a first in both maths and phyiscs. On of his theories is because there are rogue waves there can also be rogue holes. His support for that is how many tankers sank (in the late sixties, early seventies) in the Agulhas current because ther backs are broken by being suspended by big waves with a big hole in between.

I tend to agree. We were sailing upwind in a gale off St Martin and reached the crest of much bigger wave than normal and there was nothing there, just a big hole. I shouted to Jane to hold on and the boat tipped 45 to 50 degrees bow down. When the bow hit the bottom the water came uo to just before the mast, I did wonder at the time if we would keep going. If the forward hatch had been torn off I think we would have. It was all quite unpleasant and not to be recommended.

 

[Sandy]

Why wont scientists believe what observant craftsmen tell them?

They don't get any funding for that!

 

[savageseadog]

I worked with a Cambridge graduate who had a first in both maths and phyiscs. On of his theories is because there are rogue waves there can also be rogue holes..............

The absence of something isn't the existence of anything.

 

[Lady Campanula]

I seem to recall that most of these concepts have been aired, in recent years, in articles published within the Journal of the Royal Institute of Navigation and 'Seaways', the Journal of the Nautical Institute.

I also recall some lengthy correspondence, similar to some of the responses above, on the phenomena of 'rogue waves' and 'rogue holes'. As I recall, computer analysis of 'staring' ocean surveillance satellites' radar imagery indicated a much greater incidence of such than the wave-form maths predicted - and that the problems occur in all seas and in areas not necessarily noted for strong counter-currents.

I also recall my eyes glazing over at the sight of several pages of calculus intended to explain the errors in the conventional math theory......

 

[James Marinero]

Rogue Wave = Rogue Trough = Big Hole

Also, the Schrodinger equation mentioned in the story is not his quantum mechanics equation, but the classical wave theory equation. Can't remember from physics days whether first becomes the second in the limit.

 

[guernseyman]

Also, the Schrodinger equation mentioned in the story is not his quantum mechanics equation, but the classical wave theory equation. Can't remember from physics days whether first becomes the second in the limit.

No, I don't think the equations are related in that way, more a transformation of the variable.

Talking of holes in the water, I once saw a series of holes about the size of a dustbin in the Big Russel north of Sark. Quite unnerving. I don't think they were so much a wave effect, more of an overfall effect as the tide was springing and had run between Herm and Sark, an area notorious for swirls and upflows.

 

[Amulet]

Also, the Schrodinger equation mentioned in the story is not his quantum mechanics equation, but the classical wave theory equation. Can't remember from physics days whether first becomes the second in the limit.

And he murdered the ship's cat. (Maybe)

 

[johnalison]

And he murdered the ship's cat. (Maybe)

No. He got off on a technicality. The cat was both dead and alive.

 

[onesea]

,,,,,,and reached the crest of much bigger wave than normal and there was nothing there, just a big hole......

Talking of holes in the water, I once saw a series of holes about the size of a dustbin in the Big Russel north of Sark. Quite unnerving.,.

Must admit my sailing partner always worried about big waves, I always replied to watch out for the holes. Last time we where out for a play wind against current with a bit of a breeze, she soon stopped worrying about big waves...
Occasionally I would hear "ohh big hole"...

Cannot remember to many big waves that worried me its normally the hole on the other side...

 

[Simondjuk]

At least you don't get breaking holes though.

 

[binch]

waves

Some lovely responses.
I always based my calculations on an amalgam of Fourier series's's
Ir worked out.
It has always been another old sailor's dictum that it isn't the height of a wave that matters it's the depth of the hole before and after it that kills the ship.
And all too often it is the fact that the ship is going too fast.
That happened to me in HMS Wizard, a destroyer whose captain thought that speed and manliness were correlated. (Imagine being navigator to an idiot like that, a sort of primeval Jeremy Clarkson)
We went off the top of the wave and it seemed as if we were going vertically down until we hit the bottom with a bang that caused all the false teeth in the ship to collect in the forepeak.
Whatever induced me to go ocean cruising in a yacht after Atlantic convoys.Masochism, I suppose.
It was raspberry jelly, the better to be able to see it.

 

[bbg]

Sea wave height can be modelled with Schrodinger's wave equation ............

Does that mean the wave can be in two places at the same time?

 

[alahol2]

Probably.

 

[Seagreen]

It just so happens that i've just finished watching a brilliant "Horizon" documentary about Rogue waves. This was broadcast about 3 years ago, but just resurfaced on 'eden' channel.

Not going into specifics, but the prog concluded that there were 2 reasons why "rogue" waves formed; one being the oceanic version of wind-over-tide (like the Aghulas), which is now easier to plan for and route-around, but also the far more disturbing Schrodinger's wave, which can seemingly appear anywhere on earth in extended bad weather. It appears from accurate Radar mapping of the ocean surface that four 30m waves and twentyfour 27m waves appeared in one weeks' data. These waves can appear without warning in a normal heavy sea and appear as twice the wave height of other waves, coming accross the wave train at an angle, with a huge steep front (almost vertical) and rear face and massive troughs preceeding and following. Non-linear waves seem to aborb the energies of the waves ahead and behind them to form a flat wall of water with a huge hole in front, into which the unlucky ship drops.

Now showing on Eden+1 "Horizon: freak wave"