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