I've been kind of interested in some of the posts about Lake Erie conditions
to see references to 12 foot waves. I know the waves are shorter and steeper
there due to the lighter water and shallow depths. Twelve footers would
considered pretty big however, even on the ocean.

I've been pretty involved in past years with marine safety and accident
investigation projects and this gave me a chance to look into wave height
reports. There is a pretty consistent tendency for even experienced seaman
to over estimate wave heights by about 100 percent.

There is a way to estimate wave height with fair accuracy. I've done it and
then looked at what I know to be six foot waves a minute or two later and
still been unable to convince my brain that I was not looking at twelve
footers. There are some physical as well as perceptual reasons for this.

For reasons that are more psychological, there is also a tendency to
overestimate heel angles by about the same proportion. This has influenced
accident investigations when observations have been accepted as fact.

If you'd like a good sea story, and to get some idea where I'm coming from,
read "Pride of the Sea" by Tom Waldron. My name pops up frequently through
this story of the loss of the "Pride of Baltimore."

A drier, but in some ways more technically interesting book is, "Tall Ships
Down" by Daniel S. Parrott. I also have a couple lines of page numbers after
my name in the index of this book and was involved in the post mortum of
three of the five accidents discussed.

If you saw the History Channel "Deep Sea Detectives" show about the sinking
of the ship that took Admiral Byrd's aircraft to Antarctica, you also saw me
at the end discussing her loading and stability.

I just mention these things because I'll be pretty active in this news group
now that I'm getting back into sailing and cruising and people may as well
know who I am.

--

Roger Long

Welcome back, Roger. Glad to have you here. Wait around a bit and hoary will
tell you of the 40 foot waves menancing Annapolis.

I've been kind of interested in some of the posts about Lake Erie conditions
to see references to 12 foot waves. I know the waves are shorter and steeper
there due to the lighter water and shallow depths. Twelve footers would
considered pretty big however, even on the ocean.

I've been pretty involved in past years with marine safety and accident
investigation projects and this gave me a chance to look into wave height
reports. There is a pretty consistent tendency for even experienced seaman
to over estimate wave heights by about 100 percent.

There is a way to estimate wave height with fair accuracy. I've done it and
then looked at what I know to be six foot waves a minute or two later and
still been unable to convince my brain that I was not looking at twelve
footers. There are some physical as well as perceptual reasons for this.

For reasons that are more psychological, there is also a tendency to
overestimate heel angles by about the same proportion. This has influenced
accident investigations when observations have been accepted as fact.

If you'd like a good sea story, and to get some idea where I'm coming from,
read "Pride of the Sea" by Tom Waldron. My name pops up frequently through
this story of the loss of the "Pride of Baltimore."

A drier, but in some ways more technically interesting book is, "Tall Ships
Down" by Daniel S. Parrott. I also have a couple lines of page numbers after
my name in the index of this book and was involved in the post mortum of
three of the five accidents discussed.

If you saw the History Channel "Deep Sea Detectives" show about the sinking
of the ship that took Admiral Byrd's aircraft to Antarctica, you also saw me
at the end discussing her loading and stability.

I just mention these things because I'll be pretty active in this news group
now that I'm getting back into sailing and cruising and people may as well
know who I am.

--

Roger Long

Twelve footers would considered pretty big however, even on the ocean.

ROFL!

Roger Long wrote:
I've been kind of interested in some of the posts about Lake Erie conditions
to see references to 12 foot waves. I know the waves are shorter and steeper
there due to the lighter water and shallow depths. Twelve footers would
considered pretty big however, even on the ocean.

I've been pretty involved in past years with marine safety and accident
investigation projects and this gave me a chance to look into wave height
reports. There is a pretty consistent tendency for even experienced seaman
to over estimate wave heights by about 100 percent.

Years ago, when I used to fly tests for the US Navy, part of the test
report was the sea state. Even though it's not the same as wave height,
sea state is closely related to wave height, wind speed, etc. It's more
a "roughness" measure and is determined from the air by the density of
whitecaps and goes from 0 to 9, but we usually wouldn't conduct tests in
anything higher than 5. It was usually a coordinated test, me in the
air and some surface and/or subsurface assets. The number I came up
with from 200 to 1000 feet up was almost invariably at least one lower
than what the boat came up with bobbing on the surface.

Steve

The method for getting accurate wave height data from a boat is to know the
height above the waterline of some points at different heights. You then
stand on one and stretch or crouch until you find yourself looking across
the tops of the waves when the boat is in the trough. It usually takes a
few waves to get an average but it's quite striking when you get the right
position. You then measure from eye to feet and add it to the height known.
That's the average wave height.

The first time you do this, you'll probably find yourself lying flat on the
deck trying to get the right angle. Like I said, waves always look a lot
higher than they really are.

It's almost impossible to measure the height if individual waves. However,
if you know the average wave height, you can then proportion by eye and get
a reasonable estimate. I still wouldn't trust my own estimates just looking
quickly without going through the above procedure. There are just too many
illusions and too few reference points.

I've often been amused to have even fairly experienced sailors say that the
waves must be eight feet. I usually don't point out that our eyes are
perhaps six feet above the surface and we can still see all the tops when we
are down in the trough.
--

Roger Long



"Steven Shelikoff" wrote in message
...
Roger Long wrote:
I've been kind of interested in some of the posts about Lake Erie
conditions to see references to 12 foot waves. I know the waves are
shorter and steeper there due to the lighter water and shallow depths.
Twelve footers would considered pretty big however, even on the ocean.

I've been pretty involved in past years with marine safety and accident
investigation projects and this gave me a chance to look into wave height
reports. There is a pretty consistent tendency for even experienced
seaman to over estimate wave heights by about 100 percent.

Years ago, when I used to fly tests for the US Navy, part of the test
report was the sea state. Even though it's not the same as wave height,
sea state is closely related to wave height, wind speed, etc. It's more a
"roughness" measure and is determined from the air by the density of
whitecaps and goes from 0 to 9, but we usually wouldn't conduct tests in
anything higher than 5. It was usually a coordinated test, me in the air
and some surface and/or subsurface assets. The number I came up with from
200 to 1000 feet up was almost invariably at least one lower than what the
boat came up with bobbing on the surface.

Steve

Roger Long wrote:

The method for snip


Your question has certainly sparked a bunch of babble, with a few key
ideas...
If you would like one of last years answers, take a look at the site:
http://www.ndbc.noaa.gov/station_page.php?station=45005
then select the link labeled "significant wave ht" about 7/8 down the page.
This suggests April and October are the most likely for larger waves,
all under 4 meters in west Lake Erie.

Depending on how much you to explore, you will find other sources with
different answers...
All of which are perhaps rhetorical, your new boat will probably be
uncomfortable well under the max. and you will probably have the good
sense to hide from them until you can be comfortable in the seaway.

I've numerous friends confirm the great lakes are often more difficult
for the shorter period than open ocean.
In your 32, and depending on your crews stomachs, you might find about
1.5meter to be your limit on your trip.
No matter if it is 1 or 5, a green crew is about worthless...most
certainly not having fun.

Hope you fully enjoy the delivery, with your history on the water it
should be a good trip...

Skip

I have seen crew on the boat I have been on report waves as 8 feet high, when
the wave did not come above the boat's freeboard, and crew on other boats in
the same water at the same time report waves of 20 feet. All in water that
won't support 8 foot waves without breaking.

The method for getting accurate wave height data from a boat is to know the
height above the waterline of some points at different heights. You then
stand on one and stretch or crouch until you find yourself looking across
the tops of the waves when the boat is in the trough. It usually takes a
few waves to get an average but it's quite striking when you get the right
position. You then measure from eye to feet and add it to the height known.
That's the average wave height.

The first time you do this, you'll probably find yourself lying flat on the
deck trying to get the right angle. Like I said, waves always look a lot
higher than they really are.

It's almost impossible to measure the height if individual waves. However,
if you know the average wave height, you can then proportion by eye and get
a reasonable estimate. I still wouldn't trust my own estimates just looking
quickly without going through the above procedure. There are just too many
illusions and too few reference points.

I've often been amused to have even fairly experienced sailors say that the
waves must be eight feet. I usually don't point out that our eyes are
perhaps six feet above the surface and we can still see all the tops when we
are down in the trough.
--

Roger Long



"Steven Shelikoff" wrote in message
...
Roger Long wrote:
I've been kind of interested in some of the posts about Lake Erie
conditions to see references to 12 foot waves. I know the waves are
shorter and steeper there due to the lighter water and shallow depths.
Twelve footers would considered pretty big however, even on the ocean.

I've been pretty involved in past years with marine safety and accident
investigation projects and this gave me a chance to look into wave height
reports. There is a pretty consistent tendency for even experienced
seaman to over estimate wave heights by about 100 percent.

Years ago, when I used to fly tests for the US Navy, part of the test
report was the sea state. Even though it's not the same as wave height,
sea state is closely related to wave height, wind speed, etc. It's more a
"roughness" measure and is determined from the air by the density of
whitecaps and goes from 0 to 9, but we usually wouldn't conduct tests in
anything higher than 5. It was usually a coordinated test, me in the air
and some surface and/or subsurface assets. The number I came up with from
200 to 1000 feet up was almost invariably at least one lower than what the
boat came up with bobbing on the surface.

Steve

On Mon, 20 Dec 2004 02:56:36 GMT, "Roger Long"
wrote:

The method for getting accurate wave height data from a boat is to know the
height above the waterline of some points at different heights. You then
stand on one and stretch or crouch until you find yourself looking across
the tops of the waves when the boat is in the trough. It usually takes a
few waves to get an average but it's quite striking when you get the right
position. You then measure from eye to feet and add it to the height known.
That's the average wave height.

I'm reassured. That's the approach I take when trying to make
estimates and I'm usually fairly consistent with what the Coast Guard
is broadcasting. I was wondering if you had some other secret trick.

I've often been amused to have even fairly experienced sailors say that the
waves must be eight feet. I usually don't point out that our eyes are
perhaps six feet above the surface and we can still see all the tops when we
are down in the trough.

Losing all the shoreside lights in the troughs can be quite dramatic,
and they are definitely higher off the water than the rest of the wave
crests.

Ryk

Check out some real waves
http://seriesdrogue.com/stormyseas/

On Mon, 20 Dec 2004 18:57:23 -0500, "Bruce on horizon"
wrote:

Check out some real waves
http://seriesdrogue.com/stormyseas/

There was one tanker shot there I thought she was going straight to
the bottom. My father was in the British Merchant Marine and said the
worst part of a storm was when the wave period was rapid enough to
produce crests shorter than the ship's length. More than once during
the war, large frieghters snapped in half because they spanned two
crests, he's said.

Everything's relative. You wouldn't notice a bad day on Lake Erie at
sea (unless you were on a rapidly shoaling inlet, I suppose).

The thing about Great Lakes waves is their very short period and
irregular presentation, usually called "heavy chop" or "square waves".
If five midgets are rapidly pummeling a heavyweight fighter with
short, sharp blows, he'll feel it and he'll eventually go down. Same
on the Great Lakes, with the caveat that the small-boat crew in a blow
can become physically exhausted by the whipping motion before the boat
fails them in any serious way. You see this at C&C regattas in heavy
air, where people come back from a day's racing with busted arms,
sprains and smacked heads, because the motion can get so violent in
those three-to-five foot "square waves".

The Great Lakes have a pretty good record of taking down big, capable
ships. Learn to sail them in horrible weather on a lightweight boat
and I have heard it said you will be well on the way to mastering
offshore heavy weather.