Australian yacht hit by 12 meter wave - helmsman lost
 

http://www.abc.net.au/news/newsitems...5/s1912132.htm

Australian yacht hit by 12 meter wave - helmsman lost
 

On May 2, 9:22?am, Wayne.B wrote:
http://www.abc.net.au/news/newsitems...5/s1912132.htm

Isn't that about 40 feet? Good grief.

What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?

Too bad for the guy washed overboard. It would be nice if they can
find him, but odds are pretty slim. Wonder if he was wearing a vest,
with a personal EPIRB? Coulda, woulda, shoulda... pretty sad.

Australian yacht hit by 12 meter wave - helmsman lost
 

On 2 May 2007 09:35:01 -0700, Chuck Gould
wrote:

What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?

I'm not an oceanologist but I think I understand the process. On the
open ocean 10 to 12 foot waves are not at all uncommon, especially if
an active weather front has passed through recently. These waves are
fairly benign, i.e., they are not usually steep or breaking in deep
water. They do travel a long way before dissipating however. As a
result it is not uncommon to have 2 or 3 different wave trains passing
through an area at the same time, frequently from different
directions. Peak wave height then becomes a statistical probability
excercise of computing the chances that these multiple wave trains
will all happen to coincide at a given time and place. When that
happens, either a much larger than average wave is created, or just as
probable, a deep hole. Either the wave or hole is an anomaly which
gravity will try to destroy as quickly as possible with
collapsing/breaking water.

Australian yacht hit by 12 meter wave - helmsman lost
 

On Wed, 02 May 2007 13:07:50 -0400, Wayne.B
wrote:

On 2 May 2007 09:35:01 -0700, Chuck Gould
wrote:

What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?

I'm not an oceanologist but I think I understand the process. On the
open ocean 10 to 12 foot waves are not at all uncommon, especially if
an active weather front has passed through recently. These waves are
fairly benign, i.e., they are not usually steep or breaking in deep
water. They do travel a long way before dissipating however. As a
result it is not uncommon to have 2 or 3 different wave trains passing
through an area at the same time, frequently from different
directions. Peak wave height then becomes a statistical probability
excercise of computing the chances that these multiple wave trains
will all happen to coincide at a given time and place. When that
happens, either a much larger than average wave is created, or just as
probable, a deep hole. Either the wave or hole is an anomaly which
gravity will try to destroy as quickly as possible with
collapsing/breaking water.

Discovery Channel had a great episode on these waves - it was quite
interesting and made the case for several causes, but the most common
apparently is phase coupling - where a group of waves combine to
create monster waves.

According the satellite surveillance (I believe it's called the ESKA
satellite), they are very common sometimes doubling or tripling the
height of the surrounding waves, but they are rare to encounter.
Thanks to some computer modeling, waves, in theory, can reach as high
as 120 feet peak-to-peak. There is some speculation that these types
of waves, in particular in storm fronts, may actually exist. The
satellite tracked one which was 90 feet high and lasted for something
like five minutes.

I'm sure our friend from down under didn't watch that one though -
went against everything she postulated. :)

Australian yacht hit by 12 meter wave - helmsman lost
 

I'm not an oceanologist but I think I understand the process. On the
open ocean 10 to 12 foot waves are not at all uncommon, especially if
an active weather front has passed through recently. These waves are
fairly benign, i.e., they are not usually steep or breaking in deep
water. They do travel a long way before dissipating however. As a
result it is not uncommon to have 2 or 3 different wave trains passing
through an area at the same time, frequently from different
directions. Peak wave height then becomes a statistical probability
excercise of computing the chances that these multiple wave trains
will all happen to coincide at a given time and place. When that
happens, either a much larger than average wave is created, or just as
probable, a deep hole. Either the wave or hole is an anomaly which
gravity will try to destroy as quickly as possible with
collapsing/breaking water.

So if this is true then a system, in the future, could be developed to
map the probability of encountering this phenomenon in a given area
based off the prescence of certain criteria. It could work like a
weather map but show basic probablity of encounter in a given area.
This would at least give some way of increasing safety by planning a
route or time change. Of course it would only be a probability and
not a gauranteed incident of encounter.

Australian yacht hit by 12 meter wave - helmsman lost
 

"Chuck Gould" wrote in message
ups.com...


What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?



I used to be able to ... doing cannonballs off of the slip.

Eisboch

Australian yacht hit by 12 meter wave - helmsman lost
 

RCE wrote:
"Chuck Gould" wrote in message
ups.com...

What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?



Had friends on a large cruise ship in a hurricane off Cape Horn. They
got hit by two in a row. Even the crew thought they were goners. Swept
deck furniture off the 11th deck.
Gordon

Australian yacht hit by 12 meter wave - helmsman lost
 

Chuck Gould wrote:
On May 2, 9:22?am, Wayne.B wrote:

http://www.abc.net.au/news/newsitems...5/s1912132.htm


Isn't that about 40 feet? Good grief.

What do oceanologists say about the generation of a rogue wave?
Anybody know? When conditions are fairly benign, say maybe 8-10 foot
swells, what oddball force kicks up a single, 40-foot, steep and
cresting wave?

Too bad for the guy washed overboard. It would be nice if they can
find him, but odds are pretty slim. Wonder if he was wearing a vest,
with a personal EPIRB? Coulda, woulda, shoulda... pretty sad.


I seem to recall something about underwater landslide being a possiable
cause. But it is sort of a faint memory.

Capt Jack R..