By Wayne Spivak, National Press
Corps United States Coast Guard Auxiliary
Have you ever tried shouting across a
small lake? Easy, isn't it?
How about when you've been water-skiing,
and try to get the attention of the towboat? Found it impossible, didn't
you???
Sound does and does not carry over water
well. On calm lakes, bays, creeks, or in restricted visibility, sound
carries exceptionally well. If you ever went camping around a lake,
knowledgeable campers often would tell you to keep the noise down at
night, since cool air, and a flat-water surface amplified the sound you
were making, so that everyone on the lake heard you.
According to Howard Shaw, Ph. D. and
Cheryl Jackson Hall, Ph. D., "Experience suggests that sound, like
light, travels (more or less) in straight lines. However, to the
contrary, sound actually tends to curve downwards over a lake's
surface."
"Sound traveling along straight lines
would disperse quickly into the space above the lake. Instead, sound
that "should" rise up and be lost typically curves back down to the
lake/ground level. Therefore, it sounds louder than it "should." This is
a well-known and easily demonstrated observation, measurable out there
on real lakes."
But, let us go back to our water-skiing
incident. The water isn't flat; it is a jumble of waves in all
directions. Why? Because the towboat is throwing a wake, your water skis
are throwing its own wake, and with the towboat serving and changing
course to give you - the rider - a great time, the water has become
choppy.
So our wave infested lake, stops your
voice from traveling. If this were a large body of water, the wind would
be causing the waves. In both instances, the sound of your voice would
have difficulty in being heard over the sound of the waves and the
interference that the waves would produce to your voice. Add to your
problems is the pitch of normal adult voice. It would have problems
piercing the noise, and because it's a lower wavelength, it would also
have difficulty moving around the waves themselves.
So how can you be heard? By using a "low
tech solution" - an emergency whistle!
An emergency whistle costs under $7.00,
usually comes with a lanyard, which can attach to your PFD. Every member
of your boat crew and guest should be familiar with their PFD, its
emergency whistle and mirror. A whistle and a mirror, two low cost, low
tech emergency solutions that can just save your life. So the next time
you go to the boat store, why not pick up a signal mirror and a whistle
and attach it to your PFD. Low Tech Safety Items – they might just save
your life!
For more information about boating
safety, contact your local Coast Guard Unit, (https://www.uscg.mil) and ask them when the Coast Guard Auxiliary is
giving their next boating course. Or use the United States Coast Guard
Auxiliary Flotilla finder, (www.cgaux.org/units.php)
and contact your local Flotilla and increase your knowledge about
boating safety.