Subject: Wave heights
From: "Roger Long"

There is a way to estimate wave height with fair accuracy.

Do you mean knowing your height of eye and using that to measure the wave
height?

Capt. Bill

A National Weather Service table shows probable wave heights of 12 feet
being produced by 27 to 28 knot winds. These heights are for fully
developed seas and it takes several hours for them to build up.

Another common over estimation is wind speed. I was quite surprised when I
started carrying a pocket wind gauge with me while sailing. We tend to
perceive wind force rather than speed; especially when observing the
response of a sailboat. Adding a bit less than half to the wind speed
doubles its pressure. If a breeze feels twice as strong as one we know to
be 15 knots, most people would call it 30 knots whereas it would actually
only be 21.

The formula is Velocity squared x .0041.

--

Roger Long

"Roger Long" wrote in message
news ( snip )
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
Hi Roger.
In my more than 40 years of boating on the Great Lakes there is one thing
that I have learned about boating on Lake Erie. I do not take my 9 meter
power boat out into the waves of Lake Erie if the forecast is for waves of
over one meter. My boat is a Doral and I know that it can take the
pounding, but, I can not!

Jim Carter, Port Captain
"The Boat"
Bayfield

On Tue, 21 Dec 2004 11:31:58 GMT, "Roger Long"
wrote:
If a breeze feels twice as strong as one we know to
be 15 knots, most people would call it 30 knots whereas it would actually
only be 21.
=============================

Somewhere between 30 and 35 knots the wind begins to rip off the wave
tops and send them through the air like the stream from a fire hose.
I've found it to be an infallible guide to near gale force conditions.
Also, the rigging begins to howl like a banshee in that wind range and
above.

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.

Like my new pal Wally, I've been on, in and over Lake Erie for 50 years.
I worked as a lifeguard at Pt. Pelee National Park for 5 years in the
mid- 70's and we used to see lots of 6ft-8ft days. It was great for
body-surfing but not so hot for sailors. One day we watched a guy in
what looked like a Sirius 15 or 17 trying a beam reach to outrun a
westerly squall. Lee shores can be a bitch. When he finally got pushed
into the breakers, his small boat got pitched over and he got tossed
out. You can imagine the scene when a boat with a 20ft mast is being
turned turtle in 5 ft of water. The next breaker lifted the boat up and
onto the tip of the mast, which snapped under the pressure. As the boat
dropped, the broken section of the mast punched a hole through the hull.
Most impressive! He was wearing a PFD and got pushed safely in the
last 200ft or so to shore, but the boat was beaten to pieces over the
next few hours.
I can only recall one event where the waves may have reached the 12 foot
level and maybe even higher. In the 80's there was a ENE storm that ran
up the length of the lake. When it hit the eastern shore of Pt. Pelee,
it washed away approximately 1 mile of the tip. It also knocked flat a
construction block building situated behind cedars approximately 100
feet back from, and about 6ft higher than the water's edge. It also
ripped out about 1500 ft of asphalt roadway also located well back from
the water's edge. I think 12 footers are once in a lifetime events on
Erie, but I could be wrong.

the wind starts blowing the tops off waves in streaks of foam about 24 knots.

Somewhere between 30 and 35 knots the wind begins to rip off the wave
tops and send them through the air like the stream from a fire hose.
I've found it to be an infallible guide to near gale force conditions.
Also, the rigging begins to howl like a banshee in that wind range and
above.

Those are streaks on the water surface. He's talking about the tops blowing
off and keeping right on going. It really gets your attention the first
time you see it.

--

Roger Long



"JAXAshby" wrote in message
...
the wind starts blowing the tops off waves in streaks of foam about 24
knots.

Somewhere between 30 and 35 knots the wind begins to rip off the wave
tops and send them through the air like the stream from a fire hose.
I've found it to be an infallible guide to near gale force conditions.
Also, the rigging begins to howl like a banshee in that wind range and
above.

what ever would you expect from bunch of canucks. the tops of waves are blown
off in streaks of foam starting about 24 knots. That that 35 knots or 85
knots, or whatever makes you think that little chickie is going to be so
impressed when you tell her about your seagoing adventure that she is going to
strip off her clothes and drop back to the floor, her legs in the air and open.

From: Jack Dale
Date: 12/21/2004 7:28 PM Eastern Standard Time
Message-id:

On 22 Dec 2004 00:15:39 GMT, (JAXAshby) wrote:

the wind starts blowing the tops off waves in streaks of foam about 24
knots.

Somewhere between 30 and 35 knots the wind begins to rip off the wave
tops and send them through the air like the stream from a fire hose.
I've found it to be an infallible guide to near gale force conditions.
Also, the rigging begins to howl like a banshee in that wind range and
above.


Here is a site with wind speeds and wave heights:

http://lavoieverte.qc.ec.gc.ca/meteo...eaufort_e.html

On a delivery from Honolulu to Vancouver Island, after we picked up
the westerlies, we were broad reaching in 25 - 30 knots with gusts to
35. Our estimate of wave height (trough to crest) was 12-15 feet.

Jack

_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
_________________________________________________ _

Roger, you said it yourself right from the start. most people (and even more
so on this ng) over report wave height by a factor of 2x to 3x and wind
strength by almost as much.

I have seen people reefed when no whites are anywhere, and tell tales later of
25 knots gusting to 35.

Those are streaks on the water surface. He's talking about the tops blowing
off and keeping right on going. It really gets your attention the first
time you see it.

--

Roger Long



"JAXAshby" wrote in message
...
the wind starts blowing the tops off waves in streaks of foam about 24
knots.

Somewhere between 30 and 35 knots the wind begins to rip off the wave
tops and send them through the air like the stream from a fire hose.
I've found it to be an infallible guide to near gale force conditions.
Also, the rigging begins to howl like a banshee in that wind range and
above.

On Wed, 22 Dec 2004 01:30:40 GMT, "Roger Long"
wrote:

Those are streaks on the water surface. He's talking about the tops blowing
off and keeping right on going. It really gets your attention the first
time you see it.

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

Oh yes. It also gets your attention when it hits you or flys
horizontally through your companionway.