Re: Rogue waves
I'm trying to get that link to work - I turned off "Wrap message
text" this time.
Here's an article that adds support for the lifeline idea. Add
boarding features to that short list of disaster prevention measures
and this man's day would not have turned out quite so bad.
-Jerry
SF Pelican 12
<http://www.baycrossings.com/Archives/2003/10_November/harbor_bay_ferr
y_rescue_drama.htm>
text" this time.
Here's an article that adds support for the lifeline idea. Add
boarding features to that short list of disaster prevention measures
and this man's day would not have turned out quite so bad.
-Jerry
SF Pelican 12
<http://www.baycrossings.com/Archives/2003/10_November/harbor_bay_ferr
y_rescue_drama.htm>
Here's an article that adds support for the lifeline idea. Add
boarding features to that short list of disaster prevention measures
and this man's day would not have turned out quite so bad.
-Jerry
SF Pelican 12
<http://www.baycrossings.com/Archives/2003/10_November/harbor_bay_ferr
y_rescue_drama.htm>
boarding features to that short list of disaster prevention measures
and this man's day would not have turned out quite so bad.
-Jerry
SF Pelican 12
<http://www.baycrossings.com/Archives/2003/10_November/harbor_bay_ferr
y_rescue_drama.htm>
Honestly I've never gotten much mileage from the Fourier Transform. Too
much work before computers, but the concept is enlightening. If "random
superposition" won't do it, might there be some unidentified driving force?
As to "Seaworthy Offshore Sailboats," John Vigor wrote a very interesting
book by that title. As part of each topic/chapter, he instructs us to
"Think upside down." After we address the question of self-righting and
pumping dry, we then need spare spars for jury rigging, etc. and we need to
insure that the tools and spares have remained with the boat.
The Chebacco I'm building will not be a seaworthy offshore boat. I'm
looking for a trailer sailer with which to explore the rivers and lakes here
in the Midwest. The "cabin" is devolving into a hard dodger to keep off the
sun and provide some privacy for the head. More of a campsite or scruffy
motel room than a home away from home. Birdwatcher certainly has a lot to
recommend it, but one sits on the bottom and Chebacco is prettier.
A life line is a good thing. The Sunfish sailed off without me one time and
since then I've lashed the painter to my belt for most sails. I figure I'll
make a fine sea anchor to keep it within swimming distance.
Roger
derbyrm@...
http://derbyrm.mystarband.net/default.htm
much work before computers, but the concept is enlightening. If "random
superposition" won't do it, might there be some unidentified driving force?
As to "Seaworthy Offshore Sailboats," John Vigor wrote a very interesting
book by that title. As part of each topic/chapter, he instructs us to
"Think upside down." After we address the question of self-righting and
pumping dry, we then need spare spars for jury rigging, etc. and we need to
insure that the tools and spares have remained with the boat.
The Chebacco I'm building will not be a seaworthy offshore boat. I'm
looking for a trailer sailer with which to explore the rivers and lakes here
in the Midwest. The "cabin" is devolving into a hard dodger to keep off the
sun and provide some privacy for the head. More of a campsite or scruffy
motel room than a home away from home. Birdwatcher certainly has a lot to
recommend it, but one sits on the bottom and Chebacco is prettier.
A life line is a good thing. The Sunfish sailed off without me one time and
since then I've lashed the painter to my belt for most sails. I figure I'll
make a fine sea anchor to keep it within swimming distance.
Roger
derbyrm@...
http://derbyrm.mystarband.net/default.htm
----- Original Message -----
From: "boblq" <boblq@...>
> On Tuesday 31 August 2004 03:26 am, Roger Derby wrote:
> > Actually, a Fourier transform will give insight into how many
> > regular waves can combine to create a "pulse."
>
> Not really. The problem as now established
> by observation is that large waves occur
> much more frequently then can be accounted
> for by the random linear supposition of small
> waves.
>
> Once a large nonlinear wave is formed one can
> certainly decompose it with a Fourier transform
> but this does not much real insight into the processes
> that formed it.
>
> The problem for boat design is different. What
> do we do about a rare but catastrophic event?
> Designing a boat to survive a rogue wave (or
> even a wave of rouge, chuckle) may make it perform
> much worse almost all of the rest of the time ...
On Tuesday 31 August 2004 03:26 am, Roger Derby wrote:
by observation is that large waves occur
much more frequently then can be accounted
for by the random linear supposition of small
waves.
Once a large nonlinear wave is formed one can
certainly decompose it with a Fourier transform
but this does not much real insight into the processes
that formed it.
The problem for boat design is different. What
do we do about a rare but catastrophic event?
Designing a boat to survive a rogue wave (or
even a wave of rouge, chuckle) may make it perform
much worse almost all of the rest of the time ...
boblq
> Actually, a Fourier transform will give insight into how many regular wavesNot really. The problem as now established
> can combine to create a "pulse."
>
> Roger
>derbyrm@...
>http://derbyrm.mystarband.net/default.htm
by observation is that large waves occur
much more frequently then can be accounted
for by the random linear supposition of small
waves.
Once a large nonlinear wave is formed one can
certainly decompose it with a Fourier transform
but this does not much real insight into the processes
that formed it.
The problem for boat design is different. What
do we do about a rare but catastrophic event?
Designing a boat to survive a rogue wave (or
even a wave of rouge, chuckle) may make it perform
much worse almost all of the rest of the time ...
boblq
That sounds like you were at a spot called Jaws.
I think sailboarders were the first to take it on because they were the
only guys who had the speed to get into such big waves (beyond a
certain size they're just too fast to paddle into.) The one day someone
had the bright idea to use a jetski as a tow-in vehicle. I am somewhat
ambivalent about aesthetics mechanized surfing, but there's no denying
what they're doing it spectacular. Somewhere on the MavSurfer.com
website there's a link to a video of a guy riding a 70 foot wave at
Jaws.
Fortunately these monsters are quite predictable, both in timing and
location, so they're no real threat to mariners. But here's an
interesting surfing phenomenon. On any given day with a given average
sized set wave you will also have sets come through that are 50%-100%
larger, and break further out. These "clean up sets" come infrequently
enough that most people are caught closer to the beach waiting for the
day's average sized waves. (They are named clean up sets because the
effect is that they clean everyone out of the line up.) When the
average surf is 3 feet it's no big deal, because when you see them
coming you can paddle out to meet them. When it's 10 feet it can be
quite hair-raising, because the relative distances are increase, and
sometime you're not fast enough to paddle out and over them before they
break. Of course the bigger waves break much hard too, so getting
"caught inside" is much more unpleasant. Can't imagine what it would be
like to be out on a 35 foot day and then see a set of 50 footers coming
over the horizon.
-David
I think sailboarders were the first to take it on because they were the
only guys who had the speed to get into such big waves (beyond a
certain size they're just too fast to paddle into.) The one day someone
had the bright idea to use a jetski as a tow-in vehicle. I am somewhat
ambivalent about aesthetics mechanized surfing, but there's no denying
what they're doing it spectacular. Somewhere on the MavSurfer.com
website there's a link to a video of a guy riding a 70 foot wave at
Jaws.
Fortunately these monsters are quite predictable, both in timing and
location, so they're no real threat to mariners. But here's an
interesting surfing phenomenon. On any given day with a given average
sized set wave you will also have sets come through that are 50%-100%
larger, and break further out. These "clean up sets" come infrequently
enough that most people are caught closer to the beach waiting for the
day's average sized waves. (They are named clean up sets because the
effect is that they clean everyone out of the line up.) When the
average surf is 3 feet it's no big deal, because when you see them
coming you can paddle out to meet them. When it's 10 feet it can be
quite hair-raising, because the relative distances are increase, and
sometime you're not fast enough to paddle out and over them before they
break. Of course the bigger waves break much hard too, so getting
"caught inside" is much more unpleasant. Can't imagine what it would be
like to be out on a 35 foot day and then see a set of 50 footers coming
over the horizon.
-David
On Tuesday, August 31, 2004, at 11:22 AM, Nels wrote:
> I was at the Maui location once when the surf was up to about 50
> footers. You watch from the cliffs above where there is a funneling
> affect when the winds are from the north - and there is this tiny
> beach below and huge cliffs all around. Because of the height, you
> don't appreciate the sheer size of the waves until you look through
> binocs. These guys are totally insane! Not far from there and
> offshore they are tearing around on wind surfers doing 360's in the
> air, and reaching speeds beyond belief. Rather other-worldly to say
> the least!
>
> Cheers, Nels
>
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930,
> Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> Yahoo! Groups Links
>
>
>
>
>
Cortez Bank is 105 miles west of San Diego. Lots of pictures, do a
Google search...
-Jerry
Google search...
-Jerry
--- Inbolger@yahoogroups.com, David Ryan <david@c...> wrote:
footers. You watch from the cliffs above where there is a funneling
affect when the winds are from the north - and there is this tiny
beach below and huge cliffs all around. Because of the height, you
don't appreciate the sheer size of the waves until you look through
binocs. These guys are totally insane! Not far from there and
offshore they are tearing around on wind surfers doing 360's in the
air, and reaching speeds beyond belief. Rather other-worldly to say
the least!
Cheers, Nels
> Bruce,Lots of startling
>
> photos and videos at:ever
>
>http://www.mavsurfer.com
>
> These guys are way, way out of my league. The biggest thing I've
> ridden was a 15-20 foot face, and I was scare to death.I was at the Maui location once when the surf was up to about 50
>
> YIBB,
>
> David
>
footers. You watch from the cliffs above where there is a funneling
affect when the winds are from the north - and there is this tiny
beach below and huge cliffs all around. Because of the height, you
don't appreciate the sheer size of the waves until you look through
binocs. These guys are totally insane! Not far from there and
offshore they are tearing around on wind surfers doing 360's in the
air, and reaching speeds beyond belief. Rather other-worldly to say
the least!
Cheers, Nels
Bruce,
If you want to see some HUGE breakers (but not actual rogue waves) take
a drive down the coast next Winter to a spot called Maverick's.
Jeff Clark's pioneering efforts at this spot nearly singlehandedly
revived interest big wave surfing, which has proven to be the single
most commercially promotable aspect of the sport. Lots of startling
photos and videos at:
http://www.mavsurfer.com
These guys are way, way out of my league. The biggest thing I've ever
ridden was a 15-20 foot face, and I was scare to death.
YIBB,
David
If you want to see some HUGE breakers (but not actual rogue waves) take
a drive down the coast next Winter to a spot called Maverick's.
Jeff Clark's pioneering efforts at this spot nearly singlehandedly
revived interest big wave surfing, which has proven to be the single
most commercially promotable aspect of the sport. Lots of startling
photos and videos at:
http://www.mavsurfer.com
These guys are way, way out of my league. The biggest thing I've ever
ridden was a 15-20 foot face, and I was scare to death.
YIBB,
David
On Tuesday, August 31, 2004, at 10:36 AM, Bruce Hallman wrote:
>> the world. But they are not really "rogue" waves. They are rather
>> examples of the bottom topography acting to focus wave energy
>> and as such are actually fairly predictable.
>>
>> boblq
>
> I guess that is what happened in this case, quoting from the
> article:
>
> "[Mr.] Wolf said swells pick up at Bodega Rock near where
> the accident happened "
>
> Made worse, I think because of the dense fog.
>
> Still, snapping in with a lifeline, (sort of like wearing a seatbelt
> in a car) would probably be tolerable and worthwhile. 99% of
> the time in a boat you are stationary anyway.
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930,
> Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> Yahoo! Groups Links
>
>
>
>
>
> the world. But they are not really "rogue" waves. They are ratherI guess that is what happened in this case, quoting from the
> examples of the bottom topography acting to focus wave energy
> and as such are actually fairly predictable.
>
> boblq
article:
"[Mr.] Wolf said swells pick up at Bodega Rock near where
the accident happened "
Made worse, I think because of the dense fog.
Still, snapping in with a lifeline, (sort of like wearing a seatbelt
in a car) would probably be tolerable and worthwhile. 99% of
the time in a boat you are stationary anyway.
Actually, a Fourier transform will give insight into how many regular waves
can combine to create a "pulse."
Roger
derbyrm@...
http://derbyrm.mystarband.net/default.htm
can combine to create a "pulse."
Roger
derbyrm@...
http://derbyrm.mystarband.net/default.htm
----- Original Message -----
From: "boblq" <boblq@...>
<snip>
> No real theory exists for any of this yet and the observations
> (satellite data) are in their infancy. But this much is certain.
> Rogue waves are real and not just a product of some ancient
> mariners feverish dreams.
On Monday 30 August 2004 02:58 pm, Phil wrote:
Currents contain huge amounts of energy (just think of the
volume of water moving at a few knots) and if an instability
extracts energy from the directed flow into a wave then
that wave can be huge. I note that these are something
actually quite different from the effect of a large swell
being focused by the shape of the ocean bottom. These
beasts which derive energy from a current can be far larger
than any ordinary focussing effect will achieve.
To get a handle on this think of what causes an ordinary
wave, i.e. wind blowing across a water surface. The boundary
is unstable and energy is derived from the wind. A wave grows.
Now think of the Japan Current or Gulf Stream (each far larger
than the Mississippi River) flowing along an interface and
imagine how much more energy can be transfered. A wind
driven wave triggers this process but the current provides
the raw energy need to drive the wave to huge size.
But there may be another nonlinear phenomena which
enables one wave to extract energy from many other waves
growing to huge size in the process. Some such process
seems needed to explain waves in the open ocean far from
large currents.
No real theory exists for any of this yet and the observations
(satellite data) are in their infancy. But this much is certain.
Rogue waves are real and not just a product of some ancient
mariners feverish dreams.
where waves are often in the 50 ft range and probably go to 70 ft on
occasion. There are probably several dozen such spots (at least) around
the world. But they are not really "rogue" waves. They are rather
examples of the bottom topography acting to focus wave energy
and as such are actually fairly predictable.
boblq
> There are several causes of what some people would term rouge waves. AApparently one important cause is interactions with currents.
> wave pattern that is in the process of having another wave pattern
> superimposed on it by a shift in the wind can create rogue waves.
> Another cause is shallow patches of sea bottom. As the wave energy
> comes from deep water and the energy stacks up on the shallow bottom it can
> create some spectacular waves. And there are many places hundreds of miles
> offshore where the bottom gets very shallow.
Currents contain huge amounts of energy (just think of the
volume of water moving at a few knots) and if an instability
extracts energy from the directed flow into a wave then
that wave can be huge. I note that these are something
actually quite different from the effect of a large swell
being focused by the shape of the ocean bottom. These
beasts which derive energy from a current can be far larger
than any ordinary focussing effect will achieve.
To get a handle on this think of what causes an ordinary
wave, i.e. wind blowing across a water surface. The boundary
is unstable and energy is derived from the wind. A wave grows.
Now think of the Japan Current or Gulf Stream (each far larger
than the Mississippi River) flowing along an interface and
imagine how much more energy can be transfered. A wind
driven wave triggers this process but the current provides
the raw energy need to drive the wave to huge size.
But there may be another nonlinear phenomena which
enables one wave to extract energy from many other waves
growing to huge size in the process. Some such process
seems needed to explain waves in the open ocean far from
large currents.
No real theory exists for any of this yet and the observations
(satellite data) are in their infancy. But this much is certain.
Rogue waves are real and not just a product of some ancient
mariners feverish dreams.
> One place where there can be some real killer waves is Cortez Bank. ItThere is a place of the coast of Baja near Ensenada called Todos Santos
> is off the Calif coast. Waves can reach more than 70 feet in height and
> break.
where waves are often in the 50 ft range and probably go to 70 ft on
occasion. There are probably several dozen such spots (at least) around
the world. But they are not really "rogue" waves. They are rather
examples of the bottom topography acting to focus wave energy
and as such are actually fairly predictable.
boblq
On Aug 30, 2004, at 3:58 PM, Phil wrote:
Ventura, Monterey)
hal
>Where is that in relation to coastal cities I can find on a map? (IE
> One place where there can be some real killer waves is Cortez
> Bank. It
> is off the Calif coast. Waves can reach more than 70 feet in height and
> break.
> Phil
Ventura, Monterey)
hal
There are several causes of what some people would term rouge waves. A
wave pattern that is in the process of having another wave pattern
superimposed on it by a shift in the wind can create rogue waves.
Another cause is shallow patches of sea bottom. As the wave energy
comes from deep water and the energy stacks up on the shallow bottom it can
create some spectacular waves. And there are many places hundreds of miles
offshore where the bottom gets very shallow.
One place where there can be some real killer waves is Cortez Bank. It
is off the Calif coast. Waves can reach more than 70 feet in height and
break.
Phil
wave pattern that is in the process of having another wave pattern
superimposed on it by a shift in the wind can create rogue waves.
Another cause is shallow patches of sea bottom. As the wave energy
comes from deep water and the energy stacks up on the shallow bottom it can
create some spectacular waves. And there are many places hundreds of miles
offshore where the bottom gets very shallow.
One place where there can be some real killer waves is Cortez Bank. It
is off the Calif coast. Waves can reach more than 70 feet in height and
break.
Phil