1) Never Free Dive alone and select your partner
- Depth - Never dive at the same time as your partner
- Line - The safety diver watches the float line for the Freediver who must follow it at all times.
- Partner - should be easily capable of rescuing a diver from the required depth (at least 15m) and should be fully trained in rescue techniques, CPR and administration of O2 etc.
- Meeting - The objective is for the safety diver to meet the freediver and escort him - Face to Face through the area of greatest danger - which is between 15m and the surface. The depth at which they meet should be relative to the depth that the freediver has dived but not deeper than 15m. In all dives the safety diver is responsible for timing the dive and he should begin his descent at half the expected dive time.
Any dives greater than 30m require either a stand-by SCUBA
set with organised lift tackle or a safety lanyard and retrieval system. Different sea/lake conditions may require safety divers at more frequent intervals.
2) Never Free Dive after a Scuba Dive
The Nitrogen remaining in the tissues after Scuba Diving
can lead to decompression sickness when micro-bubbles are recompressed and their consequent expansion upon the rapid ascent during an ensuing freedive. Those with PFO are in a much higher risk category. Wait at least 12 hours after a Scuba Dive
before you do a Free Dive
3) Never 'ride' the flexibility of your eardrum
Equalise on descent only (about every 3m). Never force an equalisation. Never continue after a failed equalisation - abort the dive! Never equalise on ascent.
A nose clip, where used should be removed at the beginning of the ascent. "'Ramboism' The 'I must get to 40m 'syndrome. I successfully dive to 35m and equalise, cannot equalise at 38m but try for 40m nevertheless as the bottom seems close and pressure differentials are less. This is a seductive process and is nothing but a gamble on the flexibility of an eardrum. If you guess wrong the result can be a burst eardrum with its associated consequences; extreme vertigo and nausea".
4) Always be correctly weighted
It is dangerous to be over weighted. This can cause equalisation problems on descent and on ascent can cause an unnecessary expenditure of effort. Particularly dangerous with thicker suits for winter diving. A good rule of thumb is to achieve neutral buoyancy at 15m.
5) Before diving make a complete dive plan together and estimate sea conditions
It is essential that every diver working on a given dive line, knows exactly what every other diver will be doing during the course of the outing. This includes warm-ups, deep dives etc.
- Who is doing safety for whom and when.
- What to do in the event of an emergency.
- How sea conditions will affect the dive and safety i.e. current, visibility, water temperature, swell, distance from the shore and surface traffic. Current is one of the most important factors to be considered. In Fixed Weights it involves much more effort on the part of the diver to stay close to the dive line. Poor visibility as in lake diving indicates a need for more safety procedures. Water temperature effects the choice of suit and hence weights.
Surface Conditions cannot be entirely ignored and can affect the behaviour of surface traffic/ low angle sun and a choppy sea can make a Free Diver on the surface nearly invisible and care must be taken.
6) Remove the snorkel from your mouth
On returning to the surface blast clearing of the snorkel
nearly invariably leads to SWB if a diver has been close to his maximum. Retention of the snorkel at depth complicates equalisation and when diaphragm contractions begin can lead to the inhalation of water.
7) Never exhale under water or forcefully exhale on surfacing
Exhalation on descent can cause early problems with equalisation. On ascent it causes loss of buoyancy and hence more effort on the ascent which can lead to SWB. With any dramatic fall in the pressure in the lungs the remaining reserve of oxygen in the blood will go to the lung and not the brain hence causing SWB. Any diaphragmatic movement will also act as an instigator of the breathing mechanism.
by Aharon & MT Solomons
Courtesy of www.freedivers.net