What sort of floats are used in Freediving?
Recreational freedivers, spearfishers, underwater photographers etc, usually tow a float for safety purposes. A float supporting a flag is advised. Probably the greatest danger comes from boats. It is very hard to see a diver in the water, especially if you add a bit of chop on the water and the sun in the wrong position. The second safety scenario comes from the risk of diver black out. Freedivers should always dive with a buddy and use the one up and one down method. When diving in water where the visibility is below that of the depth, the diver can drop out of sight to the buddy on the surface. With a line and float, the buddy diver just follows the line down to the diver and he knows where his buddy. The freediver will also be in the right place to assist in the event of a blackout. Blackouts usually occur in the top 10 metres. Floats for this purpose are usually torpedo shaped and easy to tow.
What sort of float system do Freedivers use for depth training?
For depth training an entirely different float system is used. The float is not towed by the diver but is stationary, either drifting with the current or anchored in areas with no current. In this scenario the float is used to support a bottom weight. The purpose of this weight is to keep the rope straight. The freedivers dives to their required depths using this line as their stable point of reference. This system usually requires more than one safety diver, especially as the depth increases.
For general training the float is often a tyre tube type. The rope is fastened so hangs below the centre of the float. Almost any larger float will work so long as it can support the weight of the the bottom plate.
In competitions and very deep training this rope is usually marked off in metres and supported at the surface using a counter-balance system. This allows a weight on one side to be dropped to bring up the bottom weight. This is a safety system designed to retrieve divers who fail to surface in the expected time. There are very exact safety systems worked out for competitions and deep training. This level of training should not be attempted without expert guidance.
What is the line used to attach a freediver to the main depth rope?
This is called a Lanyard. In competition and usually the more deeper training where a counterbalance system is used each freediver must be attached to the main rope with a lanyard. If a freediver fails to surface in the expected time the counterbalance is triggered and the bottom plate and diver are pulled up from the depths. This system is especially used where the freedivers are going deeper than the safety divers can easily reach and in water depth and clarity where the freediver goes out of the sight.
The lanyard has strict requirements to its design and strength. A freediver must be able to release the lanyard easily, in the event of entanglement.