elgatoloco - 11-16-2003 at 09:35 AM
I am currently studying for an Open Water Diving certification and here is some stuff that may be of interest to some. (You know who you are)
Waves & Surf
Waves break in shallow water because the wave bottom drags on the sea floor; this slows it compared to the wave top, causing the top of the wave to
peak up and become unstable. Eventually the wave "stumbles" and breaks as surf, spilling its energy onto the beach.
The area where waves break is called the surf zone. Moderate to large surf can complicate entries and exits unless you use special techniques. You
won't find it difficult entering and exiting on a gently sloping beach through mild waves no higher than, say, your waist.
Waves break in water only slightly deeper than their height, so watching the surf tells you something about the depth. An offshore reef, wreck or
sand bar can create a shallow area that causes waves to break. Sometimes you'll see waves break, reform and break again. This indicates that the
bottom rises, drops and then rises again as you move seaward.
Sometimes waves approach shore from different directions. Depending on the angles and timing, the waves can combine into very large waves, or cancel
each other out and diminish the surf. This is why you often have a series of smaller waves - or none - followed by a series of larger waves. When
entering and exiting through surf, you watch the water and learn the wave pattern, so that you can time your entries and exits to pass through the
surf zone during the small waves.
Undertow
After a wave breaks, it flows back into the ocean under oncoming waves, causing undertow or backrush. It's not a current that pulls things far out to
sea, but you do need to be aware of it. On steep beaches backrush can be quite strong; since the waves push your upper body shoreward and the backrush
pulls your legs seaward, you have to pay attention to keep your balance during entries and exits. Avoid swimming at beaches with extremely steep
shorelines when there's anything more than very mild surf.
Currents
Waves cause many of the currents that affect swimmers. They typically approach shore at a slight angle, which pushes water down the shoreline,
creating a longshore current. A longshore current tends to push you down the beach - away from your intended exit area if you didn't know to account
for it. Another wave-generated current is the rip current. A rip current occurs when waves push water over a long obstruction such as a sand bar or
reef. The water can't flow out on the bottom, so it funnels back to sea through a narrow opening. Because they tend to be strong, rip currents can
carry you away from shore very quickly, which can be alarming if you don't know what's happening and what to do about it. You can usually recognize a
rip current as a line of turbid, foamy water moving away from shore; it also disrupts the waves where it rushes seaward.
Obviously, you want to avoid rip currents. If you get caught in one swim parallel to shore to clear the rip area. They're usually relatively narrow
and disperse quickly in deeper water. Once you're out you can swim back to shore. Never try to swim directly against a rip current.
Bajabus - 11-16-2003 at 09:40 AM
Thanks Matt!!! Happy diving
Safety in Baja waters
Ski Baja - 11-16-2003 at 06:50 PM
Speaking of safety in Baja waters, for you future snorkelers out there I thought I would point out some things to be on the lookout for. I will post
as they come to mind.
Bob and Susan - 11-16-2003 at 08:00 PM
JR
That's one of our favorite shows.....
Great picture