Freediving 101Freediving 101A Crash course to Breath hold divingA Crash course to Breath hold diving

Objectives:-Students will be able to demonstrate a working knowledge of Mammalian Dive Reflex as it pertains to breath hold diving.-Students will be able to perform the basic dive techniques: The diver’s breathe up, initial dive, and a proper dive kick.-Students will review and adhere to common sense dive safety rules and practices.

Course Goals: To learn the basic techniques, theory, and safety measures associated with breath hold diving.

Enjoy!

What is free diving?What is free diving?Also known as “apnea diving” or “breath hold diving,” free diving is simply underwater swimming without the aid of SCUBA equipment.

Free diving has existed for millennia as a way for people to collect food from the world’s oceans and other bodies of water. Today however, free divers are mostly of the recreational and sport variety.

Free divers can reach impressive depths that would be difficult even with SCUBA gear. The world record depth for a breath hold dive currently stands at over 895 feet.

What do I need?What do I need?To start freediving, you do not need any gear at all. You simply need yourself, and water deep enough to dive in. However, most free divers dive with at least a mask, snorkel, and fins. Additional equipment can include a wetsuit, weight belt, dive knife, diver’s buoy, and other gear. How much gear you use is up to you.

For a beginner, I would recommend a simple mask/fin/snorkel setup like you would buy for a snorkeling trip. A wetsuit and weight belt may also be needed depending on your local water conditions.

Mammalian Dive ReflexMammalian Dive ReflexAs humans, we are not born with fins, but we are born with the ability to dive. This is because of Mammalian Dive Reflex.

All mammals are born with this reflex, which allows us to hold our breath underwater longer than we would be able to out of water, as well as adapt to depth pressure. In humans, the reflex can be achieved by immersing the face in cool water. The effects of this are:-Decreased heart rate-Decreased blood flow to extremities-Release of extra oxygen rich red blood cells-At depths of over 30 meters, we experience blood shift, in which plasma cells fill the extra space in our lungs, keeping them from collapsing under pressure.

Review & discussionReview & discussionWhat are the effects of mammalian dive reflex on the human physiology? How are these effects initiated?

What is blood shift? Do you think this commonly experienced by recreational divers?

Why do you think humans have mammalian dive reflex?

Basic dive techniquesBasic dive techniquesBasic dive techniques include the breathe up, initial dive, kick, and for divers who use common equipment, the mask clear.

To begin, we will start with the “breathe up.” The purpose of the breathe up is simple: To free the lungs and blood of excess CO2, and fill them with as much oxygen as is possible without experiencing an oxygen related blackout during the dive.

To maintain a safe dive, take no more than three to five deep breaths. If you feel hyperventilated or dizzy AT ALL from your breathe up, you should not commence the dive. Although hyperventilation can let you stay underwater longer, it can also kill you as you may trick your body into thinking it can stay underwater longer than it can. DO NOT put this to the test, it is no joke- Even seasoned professional divers have lost their lives trying to push the limits of a breathe up.

Try It!Try It!

Go ahead!

Take a deep breath, then hold your breath with a timer running. How long did you last?

Catch your breath and try again, taking a diver’s breathe up with 3 to 5 deep breaths. Did your breath hold last longer?

Do you have a pool or water available? Try a third time with the breath up, and with activating your dive reflex by submerging your face in cool water. Is your time even better?

In the WaterIn the WaterOnce you’re able to complete a safe and effective breathe up, it is time to hit the water. The first technique we’ll cover is the initial dive. The purpose of the initial dive is to stack your bodyweight over your head in a vertical pose, which will drive you downwards, greatly reducing the effort required to dive.

To perform an initial dive, start in a normal snorkeler’s position (floating horizontally). Then, after getting a good breath, kick one leg over your head while simultaneously bending downward at the waist. Next, begin to kick your other leg over your head (following the other) and straigten out your body so you are facing directly down. If properly executed, you should now be horizontal in the water, and the shift of your body weight should drive you downwards to depths of ten to twenty feet or so.

As you dive downwards, you will need to pressurize your nasal cavity to avoid discomfort. This can be accomplished easily by pinching your nose and gently “blowing” to pressurize your ears (the same trick you would use in a descending aircraft).

Divers KickDivers KickOnce you have managed the initial dive, you’ll need to finish your descent, and then move about if you choose. To do this, you’ll need to learn a diver’s kick. “Kick” is perhaps not the best word, because contrary to what the word implies, the diver’s kick is a very subtle motion. Rather than thrashing your feet or fins wildly, your kick should start as a gentle motion at the shoulders that travels down your entire body and ends with your feet gently alternating. The purpose here is to move efficiently without using up oxygen with unnecessary effort or forced motion.

QuickTime™ and a decompressor

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Safety!Safety!When diving, safety is absolutely necessary. By not observing common sense safety rules, you can end up seriously hurt, or dead. Here are some basic rules to start with:-Always, always, always, dive with a partner- And stick with your partner. “One up, one down” is the rule, meaning that both divers should never be underwater at the same time.-Never dive in an area heavily trafficked by boats. If you do dive in an area where boat traffic is possible, use a dive buoy (with a flag) to alert boaters of your presence.-Do not dive in bad weather, you will not be able to see, it will be dangerous, and it will not be fun.-Know the local wildlife- Remember, you are intruding into another world when you free dive in the open sea. Some things bite, some sting, some have poison, and some even want to eat you, so do not dive without knowing what is in the water.-Again, DO NOT HYPERVENTILATE during your breathe up.-Lastly, there are many rules we could imagine, but the main rule to follow is: Don’t die. A common sense approach to dive safety can ensure your dives are as safe as they are enjoyable, so take care!

Dive Buoy

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Don’t Touch!

Watch out for propellers!

No Petting.

Happy Diving!Happy Diving!