100' Rogue Waves

Experts Baffled by Giant Walls Of Water

Surfersvillage Global Surf News: - - Rogue waves are the stuff of
legend and maritime myth: Giant waves, taller than highrise buildings,
that rise out of calm seas. For years scientists and marine experts
have dismissed such stories as superstition.

Walls of water do not rise out of the blue, they said. But now research
has revealed that 'killer waves' do exist and regularly devastate ships
around the world. They defy all scientific understanding and no craft
is capable of withstanding their impact.

Rogue waves in the past have been ignored and regarded as rare events,
now we are finally getting a handle on them and finding out how common
they are. These mammoth events are not tidal waves or tsunamis,
however. Nor are they caused by earthquakes or landslides. They are
single, massive walls of water that rise up - for no known reason - and
destroy dozens of ships and oil rigs every year.

The story of the super-tanker Munchen is a classic example. She was one
of the biggest ships ever built - the length of two-and-a-half football
pitches - and unsinkable, it was claimed. But on 7 December, 1978, the
pride of the German merchant navy, en route to America, disappeared off
the face of the earth. All that was found of the Munchen and her 26
crew was a lifeboat that had suffered an incredible battering.

Something extraordinary had destroyed the ship, concluded an official
inquiry, which dismissed the Munchen's sinking as a highly unusual
event that had no implications for other forms of shipping. Now
scientists believe this calm assurance may be dangerously misguided.
The destruction of the Munchen was anything but uncommon. Ships are
going down all the time. If you read the maritime press there is a boat
going down at least once a month, with the loss of crew usually
measured in dozens of lives. In the past, bad maintenance or poor
seamanship were blamed. Now scientists suspect the truth may be more
bizarre.

It is known that the Queen Mary was hit by a 75ft wall of water while
carrying 15,000 troops in December 1942. The ship came within an ace of
capsizing. Only a few years ago the British superliner Oriana was
struck by a 70ft wave that smashed windows and sent water cascading
through the ship, swamping six of its 10 decks.

These giant waves cannot be predicted by standard meteorology. Waves -
even in the worst of storms - should not reach much more than 40ft. The
fact that walls of water up to 100ft are being observed regularly
suggests that something is worryingly wrong with meteorology theory.

Waves are normally caused by high winds whipping over the sea surface,
but the origin of the freak waves baffles scientists. One theory
suggests that waves and winds heading straight into powerful ocean
currents may cause these huge walls of water to rise up out of the
deep. Another suggests that, under certain conditions, waves can become
unstable and start to suck in energy from neighbouring waves and so
grow massively and rapidly.

Researchers are still arguing over these ideas, but what is
indisputable is the fact that the design of modern ships is inadequate
for dealing with the freak waves.

"Joe" wrote
100' Rogue Waves


Even worse....
http://www.livescience.com/forcesofn...t_tsunami.html
http://www.livescience.com/php/video...AncientTsunami

Cheers,
Ellen

"Joe" wrote
100' Rogue Waves

http://www.livescience.com/php/multi...gid=319&gid=23

Cheers,
Ellen

OzOne wrote:
On Sun, 10 Dec 2006 18:51:10 -0500, "Ellen MacArthur"
scribbled thusly:


"Joe" wrote
100' Rogue Waves


Even worse....
http://www.livescience.com/forcesofn...t_tsunami.html
http://www.livescience.com/php/video...AncientTsunami

Cheers,
Ellen


Just go to sea.
Tsunami isn't a problem in deep water....the Indonesian one was waves
at sea less that 2 metres high...then it reached land......


Oz1...of the 3 twins.

That will work on a Tsunami but not a rogue.

Could your boat pop out the other side or take a washing machine ride,
a tumble in a 120 footer and still float?

Joe



I welcome you to crackerbox palace,
We've been expecting you.

OzOne wrote:
On 10 Dec 2006 17:02:30 -0800, "Joe"
scribbled thusly:


OzOne wrote:
On Sun, 10 Dec 2006 18:51:10 -0500, "Ellen MacArthur"
scribbled thusly:


"Joe" wrote
100' Rogue Waves


Even worse....
http://www.livescience.com/forcesofn...t_tsunami.html
http://www.livescience.com/php/video...AncientTsunami

Cheers,
Ellen


Just go to sea.
Tsunami isn't a problem in deep water....the Indonesian one was waves
at sea less that 2 metres high...then it reached land......


Oz1...of the 3 twins.

That will work on a Tsunami but not a rogue.

Yeah,,,the reference was to a huge Tsunami.....see above

Thats why I said yeah, that will work, then asked a question about the
original thread.

I'll go first.

I worry about my engine room hatch and cabin doors caving in.. in a
thumble. I would hope to punch thru, and not roll or tumble, or pitch
pole.... I dont think a big cat would have a chance of punching thru.

My big wave tactic would be to motor sail straight into it full
throttle, once the boat went vertical it would be a bad day/night.

Joe




Oz1...of the 3 twins.

I welcome you to crackerbox palace,
We've been expecting you.

"Joe" wrote
I worry about my engine room hatch and cabin doors caving in.. in a
thumble. I would hope to punch thru, and not roll or tumble, or pitch
pole.... I dont think a big cat would have a chance of punching thru.

My big wave tactic would be to motor sail straight into it full
throttle, once the boat went vertical it would be a bad day/night.


Are you crazy, Joe? That'd never work. Did you see the Perfect Storm movie?
Remember what happened when the Andrea Gail tried to do the same thing, It
almost got to the top but when it was almost straight up and down it went over
backwards. No, not a good plan.
This is what you should try. Act like your boat's a big surfboard and do what
surfers do. Check out the wave and look for the side that's getting shorter. Turn
your boat so it's going towards the small side about forty five degrees to the wave.
Then wait till the wave catches up and as you go up it keep steering forty five
degrees or so. Pretty soon you'll be going very fast. You'll be surfing along the
bottom part to middle part of the wave away from the side where it's big and
breaking. The face of the wave will give you the power to surf along. You can
adjust your angle to control your speed. You should try to sheet your sails in
tight because the apparent wind is going to be forward.
If your lucky pretty soon the wave's gonna get smaller and smaller. They're tall
but probably not more than a couple of miles wide. If you can keep control you can
just ride the wave till it gets small enough to handle. You've seen surfers do it on TV.
There's no reason a boat couldn't do it too.

Cheers,
Ellen

Ellen MacArthur wrote:
"Joe" wrote
I worry about my engine room hatch and cabin doors caving in.. in a
thumble. I would hope to punch thru, and not roll or tumble, or pitch
pole.... I dont think a big cat would have a chance of punching thru.

My big wave tactic would be to motor sail straight into it full
throttle, once the boat went vertical it would be a bad day/night.


Are you crazy, Joe? That'd never work. Did you see the Perfect Storm movie?
Remember what happened when the Andrea Gail tried to do the same thing, It
almost got to the top but when it was almost straight up and down it went over
backwards. No, not a good plan.
This is what you should try. Act like your boat's a big surfboard and do what
surfers do. Check out the wave and look for the side that's getting shorter. Turn
your boat so it's going towards the small side about forty five degrees to the wave.
Then wait till the wave catches up and as you go up it keep steering forty five
degrees or so. Pretty soon you'll be going very fast. You'll be surfing along the
bottom part to middle part of the wave away from the side where it's big and
breaking. The face of the wave will give you the power to surf along. You can
adjust your angle to control your speed. You should try to sheet your sails in
tight because the apparent wind is going to be forward.
If your lucky pretty soon the wave's gonna get smaller and smaller. They're tall
but probably not more than a couple of miles wide. If you can keep control you can
just ride the wave till it gets small enough to handle. You've seen surfers do it on TV.
There's no reason a boat couldn't do it too.

good suggestion for a planing hull, bad bad ideal for a non-planning
hull, drag would have you pitch poling right away.

Joe


Cheers,
Ellen

"Joe" wrote
good suggestion for a planing hull, bad bad ideal for a non-planning
hull, drag would have you pitch poling right away.


I don't think so, Joe. What's planing and what's non-planing? It's only so on
a horizontal surface. On tilted water it has no meaning. A sailboat hull can't plane
on flat water. There's not enough power in the engine or sails to make it go fast
enough. But it can when it's going downhill when the hill's steep enough. Gravity gives
you enough power. Your boat would be able to break out of the wave train it makes.
The reason is because the front of the bow wave is almost horizontal on a steep hill
of water instead of being too steep to get up like it is on horizontal water.
What do you think?

Cheers,
Ellen

Ellen MacArthur wrote:
"Joe" wrote
good suggestion for a planing hull, bad bad ideal for a non-planning
hull, drag would have you pitch poling right away.


I don't think so, Joe. What's planing and what's non-planing?


Planing allows the boat to go faster by using its speed and hull shape
to lift the front part of the hull out of the water. The boat travels
on top of the water, greatly reducing the hydrodynamic drag on the
vessel. The increase in aerodynamic drag is small by comparison, and
can be compensated for by the increased power from the sails due to the
faster speed of the craft, and by the crew trimming the sails.

The term 'planing' refers to a craft which is predominantly supported
by hydrodynamic lift, rather than hydrostatic lift (bouyancy). The
extent to which a boat is said to be planing is usually derived from
the dimensionless 'Froude Number'.

The earliest documented planing sailboat was a proa built in 1898 by
Commodore Ralph Munroe; it was capable of speeds of more than twice the
hull speed.

Planing a sailing dinghy was first popularised by Uffa Fox in Britain.
In 1928 Uffa Fox introduced planing to the racing world in his
International 14 dinghy, the Avenger. It had been designed with a hull
shape which permitted planing. He gained 52 first places, two seconds
and three third places out of 57 race starts that year.

Obviously this performance had an impact: other designers took on his
ideas and developed them. Over the years, most dinghies have acquired
some ability to plane, and there are now many high-performance dinghies
(usually called skiffs, see these examples, or these in [1]), which
will plane even in light winds, at all points of sail.


How planing works
Normally a non-planing, displacement, hull is restricted in its maximum
speed by a formula related to its overall length , where HSPD (in
knots) is maximum hull speed, and LWL is the hull length in feet at
waterline. This speed is maximised when the boat sits between the bow
and stern waves, with no intervening self-caused waves along its
length.

At low speeds, a hydroplaning hull acts as a displacement hull. But,
when the speed increases the hull begins acting as a planing hull.
However, when the boat begins to plane the formula becomes irrelevant
since the boat is climbing its own bow-wave. The bow rises slightly as
it starts by mounting its own bow wave. When it reaches the speed where
it overtakes the bow wave, the bow resumes its normal attitude. The
boat can often be seen to leave its stern-wave some distance behind it.
The hull is now planing.

Beginning to plane is the aquatic, and less dramatic, equivalent of an
aeroplane breaking the sound barrier. The aeroplane at Mach 1 begins to
pierce and go beyond its own 'bow wave', i.e. the compressed layers of
air on its front surfaces and ahead of it.

A hydroplaning hull travels faster and more efficiently than a
displacement hull of comparable size due to two factors:

less area of the hull is in contact with the water. This reduces the
friction on the hull caused by water. the hull is displacing less water
from its path. Water is relatively heavy and a displacing hull must
displace its own weight of water.

The characteristics of a planing hull are that it is narrow at the
prow, with a broader beam towards the rear. The shape of the underneath
of the rear of a larger, planing, powerboat is often V shaped. To
plane, the power to weight ratio must be high; sailing boats need a
good sail area and powerboats need a highly powered engine.

Note that under some high wind conditions, very light craft (such as
windsurfers and kitesurfers) can actually be pulled up onto the surface
of the water, or into the air, by the upward lift of the sail alone.
Although this certainly reduces water resistance, it is probably better
described as flying, rather than hydroplaning. It is also not a
sustainable state, as sailing (or kite flying) involves the extraction
of energy from the shear force between the wind and the water. If the
entire hull leaves the water, the craft will quickly come to rest
relative to the wind, and lose its lifting/driving force.


How to plane in a sailing boat
Planing can happen in a suitably designed boat in moderate to strong
winds if the crew do some or all of the following:

Sail on a reach or broad reach to begin
Slacken the jib
Raise the centreboard
Increase the speed
Keep the hull level, trapeze if necessary
Observe the wake until it is smooth and fast
Move the crew weight increasingly towards the rear to begin and to
sustain planing
Sheet in as speed increases, and apparent wind correspondingly moves
forward
Keep the boat flat and level
Bear away to maintain speed as necessary
Flick or pump the sails (although there are restrictions on doing this
in a race)
While planing, keep control of the waves and steer through them,
avoiding to increase speed to collide with the wave in front. Also, in
dinghies, keep good control of the sail power. A small change in wind
direction can easily cause a capsize, watch also out for gybes. Boat
control becomes easier as planing begins, but fast reactions are often
needed to get there, to keep the speed up and to keep the boat level.
Crew balance and trim are vital, as are sail trimming and minimal
centreboard



It's only so on
a horizontal surface. On tilted water it has no meaning. A sailboat hull can't plane
on flat water. There's not enough power in the engine or sails to make it go fast
enough. But it can when it's going downhill when the hill's steep enough. Gravity gives
you enough power. Your boat would be able to break out of the wave train it makes.
The reason is because the front of the bow wave is almost horizontal on a steep hill
of water instead of being too steep to get up like it is on horizontal water.
What do you think?

I think before I got 65,000 lbs on plane with a displacement hull I
would be in a vertical position racing to stuff the bow deep into the
wave leaving to a classic pitchpole like this:

http://www.bymnews.com/photos/albums...ormal_Git1.jpg

Joe



Cheers,
Ellen

"Joe" wrote

http://www.bymnews.com/photos/albums...ormal_Git1.jpg

Those trimarans certainly can go fast enough to pitchpole. And you're right it's usually
because they go so fast they stuff the bow into the back of a wave.
Dame Ellen can have them.
But, I don't think a monohull with ballast on the bottom would suffer such a fate. They
just don't go so fast even down the face of a wave. They would stay on the wave and never
get a chance to hit the next wave in the backside. Also, if your going across the wave at 45
degrees like a surfer you stay in place on the face of the wave even if your going very fast.
You'd have to have a boat with good rudder control. But, I think it would be a safer thing
to do than trying to go straight up a huge wave. You'd just have to hang in there till the wave
wore itself out. A wave that big just can't be that wide for more than a mile or two. What
would that be if your surfing along at ten to fifteen knots? About fifteen minutes? Doable.

Cheers,
Ellen