Freediving Equipment
Like the sport itself, when it comes to freediving equipment the watchwords are simplicity and efficiency.
Because divers and equipment undergo frequent and often great changes in depth the masks are smaller to reduce the amount of air needed to maintain pressure on descents. Their soft silicone frames mold to the face which allow for more streamlining and thus less effort underwater. Masks made for deep dives have glass lenses which do not bend and distort the view.
Compared to scuba divers apneaists use longer fins for greater propulsion. Various finning styles exist and depend largely on the diver's physique, although the classical style is generally considered to be more efficient than a bicycle pedalling-like action. Instead of using two fins, advanced divers may favour a monofin which requires much greater control and technical skill to be used efficiently. Since a comfortable and precise fit ensures maximum efficiency they are often custom made.
Weights are used to aid descent in order to counter the buoyancy effect of wetsuits and air in the lungs. Unlike scuba gear these weight belts are made of rubber which can stretch to accommodate changes in pressure better than nylon, making for a better fit and safer dive. Snorkels are the simplest item and any model with a comfortable silicone mouthpiece and uncorrugated bend can be used.
Regarding safety, snorkels should not remain in the mouth once the diver descends since the exertion of trying to clear the snorkel upon resurfacing could push a diver already low on oxygen into a blackout. This is also the reason for not choosing a corrugated bend since water can collect in the bends and interfere with breathing at the surface.
Coldness seriously compromises any breath-holding ability and must be guarded against. Wetsuits range from standard double-lining neoprene used in scuba diving to lighter single-lining neoprene popular with more frequent apneaists. Competitive or professional freedivers tend to use the very soft but expensive and equally fragile open cell suits. In addition many divers choose a nosepiece if diving with smaller goggles, or maskless, since it does aid breath holding.
Freediving Disciplines
The different breath-holding disciplines vary considerably but there are some common points. In all cases the swimming technique focuses on relaxed fluid and energy efficient movements. The athlete's head position is important during ascent and descent to maintain streamlining and to ensure optimal blood and oxygen supply to the brain. The head should be kept forward normally as if one were walking and looking ahead. When competing or training in the sea a weighted guide rope serves as a visual focus for the diver.
In Dynamic Apnea the athlete swims horizontally in a pool for as long as possible on a single breath, and an interesting feature is that instead of a weight belt, a type of weighted necklace is worn. With this necklace, and eyes focused on the bottom of the pool, the swimmer moves forward like the weighted tip of a dart. In the other pool discipline called Static Apnea the athlete holds his or her breath for as long as possible, usually at the surface.
The other events are all depth events. In Free Immersion divers descend feet first without fins by pulling themselves along a weighted rope and must then pull themselves back to the surface. Even while dependent on the guide line a good technique means that a diver can seemingly glide through the water, particularly on the ascent. In Constant Weight the divers use two fins or a monofin and swim along the surface very briefly before folding forwards and then descending parallel to the guide line.
Of all the disciplines, Constant Weight Unassisted is the purest expression of human ability in freediving and closest to the traditional method of collecting seafood that our ancestors practised. On Dec. 12, 2010, William Trubridge of New Zealand dove to an incredible 100 metres propelled only by his bare hands and feet making it the deepest unassisted dive ever recorded.
In the even deeper categories where ballast, or weight, devices are used, a No Limits descent is the most publicized, daring and dangerous feat. Here apneaists use a type of sled affixed to the guide line and may carry any amount of weight to achieve maximum depth. Due to the extreme depths reached they return to the surface using some kind of inflatable assistance such as a balloon. By comparison, Variable Weight divers are only permitted to use up to 30 kg and then must swim back to the surface unaided by a balloon or inflatable wetsuit. Lastly, the Exhale Dive is an unusual challenge: Descending on partially emptied lungs, the athlete achieves negative buoyancy very quickly and thus descends more easily than with full lungs. The catch is that the ascent is more difficult and must be done without the benefit of any oxygen reserves. Weights are not worn. This type of dive can also used to bring on the Mammalian Dive Reflex (see The Art of (Not) Breathing: Yoga Under Water) at the start of a session.
Whatever the freediver's equipment or the discipline pursued there is always one constant -- the current dive is only as good as the last breath.
Sources
- Umberto Pelizzari, Manual of Freediving, Idelson Gnocchi, 2004
Grant van der Vijver - I love nature, people and the power of words. My range of interests includes science - particularly the mystery of water, nutrition, ...
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