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Beach Diving Basics Part I — Wave Mechanics

Article originally published in our 11/2005 Newsletter by Phil Mangiaracina
Disclaimer: the guidelines described here do not replace proper training.

Beach diving is my favorite kind of diving. It’s free, it’s easy to fit into a hectic schedule, it takes less time than boat diving, I can dive at my own pace, and it’s usually less crowded than most dive boats. Despite these advantages many local divers avoid beach diving, having gotten “tumbled” once and concluding that “beach diving isn’t for them” or because surf entries and exits scare them. That’s a shame, because the hazards and frustrations of beach diving can be avoided with a little training.

Preparing to beach dive begins days before the dive. You should have some sense of what conditions will be like before you drive down to the beach. I check a handful of websites & phone numbers daily to get a “feel” for the conditions well in advance of the day I do a beach dive.

For Laguna Beach diving I recommend:

Our website! Check out Shaw's conditions from Beach City Scuba on the left side of this page.

Pacific Wilderness has a great link that gives a pictorial map of the wave pattern in the area.

Lifeguard Daily Update: The Laguna Beach lifeguards record diving & boating conditions each morning. Call (949) 494-6573 to check their report.

Check the time & height of tide changes, which can greatly impact the quality of beach diving. Large tide changes are typically accompanied by poor visibility. Also waves tend to be smaller when the tide is going out.

Ok, so you’ve been monitoring conditions for a few days. It looks like conditions are good for diving and you head to the beach. Before you gear up walk down to the beach and observe conditions for 15 to 20 minutes before entering. If you & your buddy wait until you’re all geared up you’ll it makes it really hard … and a bit embarrassing…to “call the dive.”

Everyone hears this in their Open Water course, but few experienced divers (me included) do it religiously. You need much more than the 30 seconds most divers dedicate to watching the waves before entering. This will give you a sense of whether waves are building or not, which is the only way to get a sense of what it'll be like an hour later when you exit; there’s nothing worse than entering when the size of the waves are the upper edge of your comfort zone, only to find them 50% larger when you want to exit.

There are some fundamentals to understand when doing a beach dive:

All the energy is at the top of the wave. Your goal, if you have to deal with a wave, is to “slip the punch” of the wave. This means placing yourself near the bottom of the wave. You also have to learn to “time” the waves, so you don’t find yourself standing where the wave breaks, with the wave’s energy crashing down on you. “Timing the wave” means understanding that there are really three phases of a wave:

1. When it’s forming . As a wave propagates across the ocean the energy (not the water) travels in a circle underneath a small “bump” in the water. The energy at the bottom of this circle is what creates the surge you feel as a diver, pushing you backward and forward in equal measure. The energy is distributed evenly at this point. These “round” waves present no problem for a diver on the surface; simply bob up over the wave and let it sweep past.

2. When it’s standing up . As the wave encounters the bottom the circle of energy begins to drag across the resistance, turning it into an upright oval. From the surface you’ll see a flat vertical surface, with white foam on the top... the classic “Hawaii 5-0” wave shot. The energy of the wave is transferred to the top of the wave, which is why you see that wall of water being swept upward. Where you, as a diver, want to be is at the bottom of the wave, away from all that energy. If the “flat” part of the wave is a few feet from you then simply kneel and let the energy sweep past. If the flat part of the wave is 5 to 10 feet seaward from you then you need to move quickly toward the wave before kneeling down or ducking below it. You have to fight the primal instinct to run away from danger towards the beach; the undertow of the previous wave will almost certainly hold you back or trip you, leaving you to deal with...

3. When it’s breaking . Eventually the “oval of energy” will become unstable and tip over, sending all that energy crashing down, tumbling over and over. If you are standing where the wave breaks, you will be sent tumbling as well. Everything will be a blur of white foam and brown sand for a few seconds. Most likely you can kiss goodbye to some of your gear. At this point your options are very limited; tuck in your arms and legs and roll with it, remembering that it will only last 5 or 10 seconds at most and that anyone can hold their breath for five to ten times that long! A quick request for help from the Almighty, if you are so inclined, might not hurt. As things begin to slow down find the bottom with your hands and knees and then stand… or crawl out on your hands and knees; safety takes priority over ego. Gladly accept the help of other divers, a lifeguard, or nearby swimmers in getting to your feet; we’ve all been there.

Your goal is to minimize your time in the surf zone . Making your way through the surf zone is usually the most difficult part of beach diving. Given this, my whole strategy is simple: Don’t spend much time there. The surf zone is typically no more than 15 feet wide and should take more than 10 or 20 seconds to cross. Some people believe you should enter and exit the surf with their fins on, shuffling backward as you go. Rodale’s Scuba Diving magazine & website periodically run articles showing this approach. A club member recently took a local class on “Rips, Rocks, and Reefs” that also taught this method. Using this method is appropriate in only a few scenarios, most of which do not present themselves off our beaches. It makes you much slower and less steady in the surf zone, where you need to be fast and solid. It is common, in Laguna Beach, to see entire groups of people (including instructors) getting knocked down by a 2' wave using this technique. We call them “turtles” because they all end up like turtles, lying on their backs with arms and legs flailing in the air. Don’t be a turtle; enter & exit without your fins on.

Waves don’t come in nice, timeable, consistent, and predictable sets. When I first started diving I expected the maxim “waves come in sets of seven” to be a great help. After hundreds of beach dives, I have yet to see a ‘typical’ set of waves. Waves can come in sets of any number. Sometimes a large wave begins the set, with succeeding waves each a bit smaller, followed by a lull. This isn’t always the case; I’ve seen waves arrive in sets of 12, with each wave being six feet tall. I’ve seen waves which had no discernable sets, just a continuous roar of 4 foot waves about ten feet apart. Simply put, the ocean doesn’t behave according to a set rule (at least one that I can articulate!).

“Timing a wave” for me means knowing what’ll come my way in the next half minute. Pay attention as a wave encounters an obstruction farther out to sea, watching it all the way to the beach. You might notice, for example, that any wave that “sprays” mist over an obstruction becomes pretty big when it hits the beach 30 seconds later. With experience, you can get a 20 second (or more) “early warning” of a big wave approaching, which is all you should need to get through the surf zone.

You can rarely overpower or outrun the ocean. All the articles I see about “bracing yourself against a wave,” sometimes with two people holding on to each other are (in my opinion) wrong and dangerous when the waves get much beyond waist height. You can “take” smaller waves by turning sideways to minimize the surface area the wave hits, crouching, and leaning into the wave a bit. This doesn’t work well with larger waves, however; your tank & BC, when turned sideways, have about the same surface area as your chest. No matter which way you turn, you’ll have more surface area above the waist than below, which will make you unstable when the wave hits.

For larger waves don’t “fight” them, work with them. Learn to time the waves so you don’t have to fight them. Instead, use the energy of the ocean to your advantage. When exiting use a smaller wave to push you towards the beach to begin your exit. When diving use the surge to move you along, then “duck and hold” to avoid being pulled backwards. Come to our Beach Clinics and learn with our members to not be the next "turtle"!

Next Lesson: Beach Diving Basics Part II – Entries and Exits