At 07:33 AM 12/24/2001 +1100, Glenn Williams wrote:
Mike.
I still say that you can't get a 10 ft wave in 10 feet of water....
REPLY
Let's make sure we are comparing apples with apples and not oranges.
There are all sorts of waves. Waveshape is also influenced greatly by
shoal bottoms, not necessarily well documented.
And then there are solitons. Although the concept was first theorized
about 150 years ago the subject has been relatively unknown in maritime
circles until recently. Then the advent of fast cat ferries brought the
subject into the public limelight due to several incidents involving
fatalities.
Recently, an advisory has been published for commercial shipping about
wave heights in the open oceans becoming much greater than previously
seen. The "experts" theorized that global warming and the resultant
weather changes was responsible.
Naturally, some experts jumped in refuting this claim as pure nonsense
citing traditional wave formation theory as justification.
The truth is, the classic model used for estimating significant wave
height under steady state wind and fetch conditons is based on
observation by seasoned skippers. The data was tested in tank testing
and apparently held up to scrutiny. However, open sea observations are
not uniform nor consistent, depending as it does on chance encounters of
ships and waves.
Only recently has oceanographic studies included daily long term
measurements of waves in deep ocean as well as shoal water conditions.
Before the advent of satellite remote sensing and GPS floating sensors
we did not have the means to accurately measure wave heights in all
places, under all conditions.
The Great Lakes is a microcosm of nautical environmental situations.
Ther are several instances of waves breaking up huge ships when the
experts figured this couldn't possibly happen in "sheltered lakes" not out
on the open ocean.
So much for experts and classic models of wave behaviour. Never
generalize and say "never"! < big grin>
Cheers
Arild Jensen
The Electronic Navigator
At 07:33 AM 12/24/2001 +1100, Glenn Williams wrote:
>Mike.
>I still say that you can't get a 10 ft wave in 10 feet of water....
REPLY
Let's make sure we are comparing apples with apples and not oranges.
There are all sorts of waves. Waveshape is also influenced greatly by
shoal bottoms, not necessarily well documented.
And then there are solitons. Although the concept was first theorized
about 150 years ago the subject has been relatively unknown in maritime
circles until recently. Then the advent of fast cat ferries brought the
subject into the public limelight due to several incidents involving
fatalities.
Recently, an advisory has been published for commercial shipping about
wave heights in the open oceans becoming much greater than previously
seen. The "experts" theorized that global warming and the resultant
weather changes was responsible.
Naturally, some experts jumped in refuting this claim as pure nonsense
citing traditional wave formation theory as justification.
The truth is, the classic model used for estimating significant wave
height under steady state wind and fetch conditons is based on
observation by seasoned skippers. The data was tested in tank testing
and apparently held up to scrutiny. However, open sea observations are
not uniform nor consistent, depending as it does on chance encounters of
ships and waves.
Only recently has oceanographic studies included daily long term
measurements of waves in deep ocean as well as shoal water conditions.
Before the advent of satellite remote sensing and GPS floating sensors
we did not have the means to accurately measure wave heights in all
places, under all conditions.
The Great Lakes is a microcosm of nautical environmental situations.
Ther are several instances of waves breaking up huge ships when the
experts figured this couldn't possibly happen in "sheltered lakes" not out
on the open ocean.
So much for experts and classic models of wave behaviour. Never
generalize and say "never"! < big grin>
Cheers
Arild Jensen
The Electronic Navigator
