G Picture a submarine, diving.
Judging wave heights, at sea is not easy. On a ship, judging heights up
to @30-40' can be done with reasonable accuracy (the bigger the ship the
better), but above that it becomes much more difficult.
If you read various books, I believe you'll find that @60' is considered
the maximum that waves can reach at sea. I feel the number is
considerably higher, but no where near 200'.
It's kinda like reporting roll angles with a "clinometer" .... "we were
rolling 40 deg by the clinometer" .... in truth, their roll angle was
closer to 20 deg.

otn

Short Wave Sportfishing wrote:


A 60 ft high ship can easily have a 30 foot wave break over it if the back
of the ship is still on top of the prior wave and the nose is in the trough.


Ok, good points, but I'm confused by this last exanmple.

Later,

Tom
S. Woodstock, CT
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

Short Wave Sportfishing wrote:
On Tue, 16 Mar 2004 23:08:02 +1100, "K. Smith"
wrote:


Calif Bill wrote:

http://tv-antenna.com/heavy-seas/




Hmmm contrary view has to be put & as always only too happy to discuss
it:-)

Thanks for the pics though, they prove yet again that "huge" waves in
open water are the stuff of over active imaginations


Ummmmm....ok, I'll bite.

Why?

Look at the pics, some show a wave seeming to be breaking "onto" the
boat?? whereas in reality the boat is ploughing "through" & in part
creating the wave, waves don't break like that in open water until they
get disturbed by the proximity of the ship's displacement.

In a couple you can see the boat is on the downward plunge so the
"apparent" huge wave doesn't exist at all, in others the wave is getting
on board, however as a rough (little pun the-)) rule of thumb waves
start to stand up when they get close to objects, rocks, beaches reefs
etc & the wave sees the ship as a blockage to the flow of the wave's
energy (it's only the energy that flows in a wave not the water itself,
the water itself mostly just scribes a small circular motion as the
wave's energy passes), so just as with every other time that happens the
first thing is the wave stands up higher, after a point (usually when
the height is the same as the depth of the obstruction) it can no longer
"stand" & breaks, once it has broken then the energy is released & the
water does move.

A good example is a couple of pics from a ways off that show ships &
the horizon behind??? as you can see in one (the tan coloured hull) the
ship is pitching well & truly, the bow is well up exposing almost all
the forward draft (the boat is pitched stern well down in the trough,
but the onboard crew wouldn't know that), the actual waves in the
vicinity are not all that big??? If you quizzed the crew they'd all
swear black & blue tall tales & true.

It's not that they're liars as such, although our own pet Rick is:-),
it's a trick of the eyes input vs the inner ear balance, the reason we
get seasick, the reason untrained (instrument) pilots can't fly in cloud
without unconsciously going into a big slow spin till the ground
intervenes even though they would & do!! swear they're flying straight &
level despite the screaming engine, the spinning instruments so strong
is the belief in our own balance system & it's the reason nasa give
their astronauts an artificial horizon reference to concentrate on.

Your eyes are the primary inputs we get attuned to & in most
circumstances what we see coincides with what our inner ear says, as
regards motion.

Once we loose a standard reference like an horizon then the inputs from
the inner ear can create deception. I boat in heavy weather is a myriad
of constantly changing accelerations, up, down, roll & pitch & when you
have no reference you imagine what your eyes are saying is correct but
not so. Again see the pics with a clear horizon in the backgrounds
suddenly the waves look modest.

At sea in heavy weather you're usually running (got not much choice on
small yachts:-)) & invariably someone comes up from below & looks astern
only to see the mythical huge wave standing up about to break upon the
boat, what this person is actually looking at is down the back of the
wave that just past under the boat, through the trough then up the steep
face of the next approaching wave, however having no reference other
than the confusion of their own balance he/she in all honesty "sees'
that all as all up & the face of an approaching huge wave.

A good "test" to try on a bumpy day is to "estimate" the swell height,
from the lower deck where you can't see the horizon, then climb to
whatever height it takes so you can still see the horizon in the
troughs, your eye height above the waterline is the real wave height,
you'll be astounded because rarely will you not see an horizon in the
troughs just standing on your normal aft deck, what?? eye height 6-7 ft.

Ships are so big it's even worse because you have so many apparently
fixed references around you, the ship "seems" immovable & therefore it's
easy to misconstrue the waves as all being "up" as if the ship is
floating in a harbour. The big wave pics out over the bow with no
horizon visible??? the boat is actually pointing well downhill the stern
still being on the last crest, but with no horizon you wouldn't know
that even if you were aware of the fact & looking for it, because as Mr
Einstein said gravity is just acceleration & our balance system is
designed to sense acceleration only. Ships in heavy weather rise up,
down, roll & pitch the same as & if being powered even slightly "into"
the weather even more so, than smallcraft, the rub is their mass/length
dictates they go through many waves rather than over them.


K


Later,

Tom
S. Woodstock, CT
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

On Wed, 17 Mar 2004 18:58:11 +1100, "K. Smith"
wrote:

Short Wave Sportfishing wrote:
On Tue, 16 Mar 2004 23:08:02 +1100, "K. Smith"
wrote:


Calif Bill wrote:

http://tv-antenna.com/heavy-seas/




Hmmm contrary view has to be put & as always only too happy to discuss
it:-)

Thanks for the pics though, they prove yet again that "huge" waves in
open water are the stuff of over active imaginations


Ummmmm....ok, I'll bite.

Why?

Look at the pics, some show a wave seeming to be breaking "onto" the
boat?? whereas in reality the boat is ploughing "through" & in part
creating the wave, waves don't break like that in open water until they
get disturbed by the proximity of the ship's displacement.

~ snippity snip ~

Interesting.

Later,

Tom
S. Woodstock, CT
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

"K. Smith" wrote in message ...
Short Wave Sportfishing wrote:
On Tue, 16 Mar 2004 23:08:02 +1100, "K. Smith"
wrote:


Calif Bill wrote:

http://tv-antenna.com/heavy-seas/




Hmmm contrary view has to be put & as always only too happy to discuss
it:-)

Thanks for the pics though, they prove yet again that "huge" waves in
open water are the stuff of over active imaginations


Ummmmm....ok, I'll bite.

Why?

Look at the pics, some show a wave seeming to be breaking "onto" the
boat?? whereas in reality the boat is ploughing "through" & in part
creating the wave, waves don't break like that in open water until they
get disturbed by the proximity of the ship's displacement.

what??? IF the boat IS plowing through the wave, and the ship's
freeboard is 30', then the wave is higher than that. If it weren't the
ship wouldn't plow through it.


At sea in heavy weather you're usually running (got not much choice on
small yachts:-)) & invariably someone comes up from below & looks astern
only to see the mythical huge wave standing up about to break upon the
boat, what this person is actually looking at is down the back of the
wave that just past under the boat, through the trough then up the steep
face of the next approaching wave, however having no reference other
than the confusion of their own balance he/she in all honesty "sees'
that all as all up & the face of an approaching huge wave.

Jeez, it can't be any more simple, if you are standing on a ship's
deck, and there is 30' between you and the water, and the wave breaks
over you, then the wave has to be greater than 30', or it could not
possibly break over you.

basskisser wrote:
"K. Smith" wrote in message ...

Short Wave Sportfishing wrote:

On Tue, 16 Mar 2004 23:08:02 +1100, "K. Smith"
wrote:



Calif Bill wrote:


http://tv-antenna.com/heavy-seas/




Hmmm contrary view has to be put & as always only too happy to discuss
it:-)

Thanks for the pics though, they prove yet again that "huge" waves in
open water are the stuff of over active imaginations


Ummmmm....ok, I'll bite.

Why?

Look at the pics, some show a wave seeming to be breaking "onto" the
boat?? whereas in reality the boat is ploughing "through" & in part
creating the wave, waves don't break like that in open water until they
get disturbed by the proximity of the ship's displacement.


what??? IF the boat IS plowing through the wave, and the ship's
freeboard is 30', then the wave is higher than that. If it weren't the
ship wouldn't plow through it.

No the boat has huge momentum via it's mass & speed, even at slow
speeds, it's pitching up & down regardless. The bow is being pushed down
via the ship's own motion. Once the boat has some pitch motion
established even a small wave will "look" like it's breaking over the
deck, but the boat is actually diving downwards, bow first.

At sea in heavy weather you're usually running (got not much choice on
small yachts:-)) & invariably someone comes up from below & looks astern
only to see the mythical huge wave standing up about to break upon the
boat, what this person is actually looking at is down the back of the
wave that just past under the boat, through the trough then up the steep
face of the next approaching wave, however having no reference other
than the confusion of their own balance he/she in all honesty "sees'
that all as all up & the face of an approaching huge wave.


Jeez, it can't be any more simple, if you are standing on a ship's
deck, and there is 30' between you and the water, and the wave breaks
over you, then the wave has to be greater than 30', or it could not
possibly break over you.

On a very calm day even a modest patrol boat can throw green water over
the deck if driven hard into a slight swell.

The boat acts like a sea wall & as you might know waves bounce up over
sea walls much higher than the surrounding wave height.

The pictures are not a testament to big waves but to how easy it is to
be deceived when our normal established references (what's up & what's
down) are taken away.

K

Great pix! Thanx...
--
Capt. Frank

__c
\ _ | \_
__\_| oooo \_____
~~~~|______________/ ~~~~~
www.home.earthlink.net/~aartworks
"Calif Bill" wrote in message
hlink.net...
http://tv-antenna.com/heavy-seas/