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

On Sun, 19 Dec 2004 18:29:14 GMT, WaIIy
wrote:

I lived on Lake Erie (near Cleveland) for 6 years and near the lake for
50 years and have never see or reliably heard of 12 footers.

The highest I have been in are 7- 8 footers and wouldn't like to do that
again.

Lake Erie is notorious due to the closeness of the waves. Everything
is a chop 1ft-2ft-6ft chop.

Of course, when it is rolling or fairly flat, it's wonderful (if quite
brown).

Lake Ontario is not dissimilar. Wave heights given on the Canadian
marine weather channels are for mid-lake...the place where the longest
fetch will produce the highest waves.

I have been out in sustained south to west to north 40 knot winds off
Toronto. After a very short time this produced six-seven foot waves
(with a 30 mile fetch up lake) or four-five from the south (23 miles).
By contrast, the strongest winds were from the north (40-45 knots
sustained in an October gale), but the waves were two feet or so due
to the short (1-2 mile) fetch.

Probably the worst (and the rarest) is a north-east to east gale due
to the 200 mile fetch. I went west to east right into the teeth of a
sustained 30 knot September gale and got very choppy six-footers. We
have an aft-cockpit sloop and with a No. 3 and a double reefed main we
were making hull speed close hauled. Lots of falling down waves and
green water on deck, but as it was sunny, it was fun. Took all day
(seven hours, maybe) to get eight NM back to our club due to the long
boards we had to make inshore and then off again. Terrific sailing,
however.

To sum up: it depends where you are in the Great Lakes and where the
wind (obviously mainly westerlies) is coming from. A huge wind with
little fetch can give you a great run down the lakes on beam reaches.

R.

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

On Sun, 19 Dec 2004 17:56:54 GMT, "Roger Long"
wrote:
Twelve footers would
considered pretty big however, even on the ocean.

==============================================

Roger, if you can believe the NOAA weather buoys, 12 footers on the
open ocean are almost routine anytime the wing is blowing 25+, and
that happens with a great deal of frequency.

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.

12 average or 12 max? What I'm talking about here is 12 foot, wind driven
waves, average height so that wave after wave is in the twelve foot range.
This means that the occasional big sea will be 18 to 20 feet. These will be
intimidating conditions to the average coastal sailor. They are not
uncommon overall but not frequently encountered by people who listen to
weather forecasts and have a choice about going out.

The distinction between swell and waves is significant. A 12 foot, long
period swell would hardly hamper a 30 foot boat at all whereas wind driven 8
footers could give it a real beating.

There is much more to it than the measurement from trough to crest which is
what got me asking about Lake Erie in the first place.

--

Roger Long



"Wayne.B" wrote in message
...
On Sun, 19 Dec 2004 17:56:54 GMT, "Roger Long"
wrote:
Twelve footers would
considered pretty big however, even on the ocean.

==============================================

Roger, if you can believe the NOAA weather buoys, 12 footers on the
open ocean are almost routine anytime the wing is blowing 25+, and
that happens with a great deal of frequency.