Question about wave action on inland lake.
 

Hi,

I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?

Question about wave action on inland lake.
 

My guess is air temperature and pressure, and the water temperature.
Course, it could have been an oil slick too, or some other chemicals doing
the same thing.
Greg Luckett

wrote in message
...
Hi,

I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?




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Question about wave action on inland lake.
 

Was the water temperature different then normal? Both viscosity and surface
tension vary with water temp which may explain the differences.

Can't help you on the hole and dirt observation. Suggest you try the
gardening news group :-)


wrote in message
...
Hi,

I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?

Question about wave action on inland lake.
 

As I recall, wave shape, frequency and height is determined by the 3 main
factors of wind speed, fetch (distance of open water) and water depth. If
you have a shallow body of water with only a modest wind speed of 15 mph
over large fetch, such as the Chesapeake Bay, this will result in a constant
chop of waves very close together in frequency. Conversely, the same wind
speed over a smaller fetch, such as a deep inland lake, will produce smaller
waves that are shaped quite differently. The waves you mentioned are
produced by a boat rather than the wind, but I wonder if the same principles
apply here as well. Perhaps the water depth where you witness this wave
action was very deep and had an effect upon the wave shape.


wrote in message
...
Hi,

I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?

Question about wave action on inland lake.
 

On Tue, 13 Apr 2004 22:57:34 GMT, wrote:
I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?
========================================

In general there seem to be two things that affect the shape of a
boats wake.

First is distance. The further you are from the boat that made the
wake, the less steep it wil become. Steep waves represent a lot of
energy, and the energy dissipates as the wave travels over a distance.

The other determinant is the type of boat and the speed it is
traveling. A fast boat traveling on plane will produce a steep
breaking wave directly behind the boat, with the height depending on
the weight of the boat and its hull shape. Large heavy boats that are
not yet on plane tend to produce a long gradual wake more like an
ocean swell.

Question about wave action on inland lake.
 

Boat wakes depend on the speed and weight of the boat, and on whether it
is planing or not. Big boats on the Rideau make smoother wakes. Boats
passing in opposite directions make interesting wave patterns. I've sailed
into a hole in the water that way. As a youth on Lake Muskoka (Ontario) I
rowed a double ender out and surfed along on the wake made by the boat
which delivered heating oil.

Waves made by the wind on sheltered waters tend to be short and sharp. On
shallow lakes like the notorious Lake Nip****ing I've ridden 3 ft waves.
Also read about 6 ft waves on inland waters (Churchill River) during
storms. There's a formula that says when the distance between waves is
less than 7 times their height the waves will curl over and break. So 1 ft
waves will break when they are only 6 ft apart. I've seen that on the
Ottawa River here.

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Question about wave action on inland lake.
 

In article ,
says...
Hi,

I have a boat on Lake Lanier in GA. The other morning I took it out,
and the overall wave action appeared to be different than usual.
It was a flat calm day, except when a passing boat produced some
waves. Most of the time the waves seem to be sort of peaked and
a bit sharp, but on this morning they were more rounded and flatter.
The first boat I noticed it from, I thought it might be simply due to
the shape of the boat itself. But after a while I noticed it was true of
all of them...which was cool with me because it meant I could go
faster without getting tossed in the air too much. It still made me
wonder *why* though. Could it have something to do with what
creates high and low tides, and/or why sometimes when you dig
a hole you seem to have more dirt than you took out and sometimes
you seem to have less? If so, is there a way to predict when waves
will tend to be sharper and when they will tend to be flatter, like
people can predict high and low tides?



I suspect that some of the differences in wave characteristics
you observe might be due to a very strong and shallow
thermocline in the lake. That might act as an artificially
shallow 'bottom' for the waves, changing their character.
At this time of the year, the lake is probably not too
stratified, and the real depth controls the waves.
Later in the summer, it may be very stratified, with
a sharp thermocline at 6 to 15 feet. (I've discovered
those when diving into apparently warm lakes!).

Another phenomenon which probably doesn't have much
to do with your observations is sieching. It is well
described at

http://www.glcclub.com/lifeline/03mar/seiches.htm

Small lakes don't usually have tides---but they can
have seiches, which can show some of the same
characteristics.

Whether it has anything to do with the amount of
dirt in holes, who knows. That phenomenon has
to do with relative compaction---a lesson I learned
as an enginering student trainee with the California
Dept. of Transportation many decades ago.


Mark Borgerson

Question about wave action on inland lake.
 

Could it be...

+ There was something in the water, like more weads or growth, that kept the
waves from building?

+ There was oil on the water. I've heard that even a thin layer of oil will
effect wave action.

+ That normally, but not this day, there is some wind that catches even
little waves and makes them a little more pronounced?

+ That normally, but not this day, there are lots of other waves from either
wind or boats that cause interference with all
the waves and make them all more pronounced?

Just guessing around.

Question about wave action on inland lake.
 

Question about wave action on inland lake.
 

On Wed, 14 Apr 2004 14:39:59 GMT, Mark Borgerson wrote:

[...]
Whether it has anything to do with the amount of
dirt in holes, who knows. That phenomenon has
to do with relative compaction---a lesson I learned
as an enginering student trainee with the California
Dept. of Transportation many decades ago.


Mark Borgerson

Thank you. What influences relative compaction?