What is Freediving - Constant Weight No Fins Discipline Explained
Description Freediving CNF
Often described as the purest form of freediving, constant weight no-fins (CNF) requires the freediver to descend and ascend along the dive-line without using fins, without changing their weighting, without using the rope (except once at the bottom to turn) and without assistance of any kind. It's the most physically and technically demanding of the depth disciplines because it requires a high rate of work and a long dive-time. For many, however, it's also the most fun because it allows for complete freedom in the water.
Constant Weight no fin: Technical Considerations
Good technique is probably more important for CNF than any of the other disciplines in freediving. Most divers use a modified breaststroke action where the arms move all the way from above the head to below the hips in a keyhole-shaped action, and the legs do a kind of frog-kick:
The CNF Freediver typically swims down to between 20 and 25 meters before entering a freefall where the negative bouyancy created by the effect of pressure on the lungs allows the diver to continue their descent without swimming. On the way up, though, this negative bouyancy must be overcome by physical effort. Good technique ensures that the freediver wastes no energy on the first part of the descent and the entire ascent and, where necessary, is able to carry out effective equalisation of the ears as part of the stroke action.
For competition and for deep dives in training, freedivers use a lanyard to ensure that they don't become separated from the dive-line. For CNF this lanyard is usually worn around the waist to avoid tangling during the large movements made by the arms and legs during the dive.
A mask is often an encumbrance in CNF because of the need to interrupt the normal stroke to equalise the ears. Most CNF divers, therefore, use a noseclip and fluid goggles, or even just a noseclip, to make the job of equalisation more easy.
CNF World Records
Women - Natalia Molchanova (RUS) 70m
Men - William Trubridge (NZL) 101m