Techniques for Deeper Diving Deeper diving is usually defined as dives deeper than 60 feet. These dives must take into consideration better use of many diving skills that we might take for granted on shallower dives: Communications Equipment Considerations Buoyancy Control Buddy System Additional Planning Personnel Dive Profile Gas Management (Air or Nitrox) Additional Hazards
Why Make Deep Dives Larger or different reef formations to see Larger soft corals (sea fans) that grow larger because they are not as affected by wave surge Different types marine life larger fish such as grouper Exploration of a deep ship wreck Blue holes Tunnels in the reef to swim through Drift dives above the Abyss along walls that plunge to very deep depths Underwater photography of all this
Reasons NOT to Dive Deeper: You Must Be In Planning Mode During the Entire Dive There is more risk You must be more aware buddy distance Nitrogen Narcosis MOD if using Nitrox (Maximum Operating Depth) Must pay very close attention to max allowable depth Must pay very close attention to max allowable bottom time Must always know location of the anchor/mooring line and have enough remaining air supply to return and make a safe assent up the line to the surface
Biggest Reason NOT to Dive Deeper: To Challenge Your Ego! Your Ego can get you injured or killed, or even worse, It can get someone else injured or killed! NEVER LET ANYONE TALK YOU INTO A DIVE THAT YOU ARE UNSURE ABOUT!
How Deep is Deep? Sport diving is limited to 130 feet. We generally define deep dives as 60 feet to 130 feet for sport divers. Junior SCUBA Divers are restricted to no greater than 60 feet by condition of their junior certification agreement with their parents. Until Junior Divers have completed the Advanced Course, they should not make dives below 40 feet without an adult buddy or Divemaster/Instructor supervision. Junior Advanced Divers can be allowed to dive to 60 feet as buddy pairs with parental consent.
How Deep is Deep? Nitrox (EANx) makes dives between 60 and 130 feet safer due to lower uptake of nitrogen. Divers are encouraged to take the NAUI Nitrox Diver Course. When you breath Nitrox you are breathing a mixture that has less nitrogen. Therefore you will have less nitrogen absorbed into your body. This lowers your chances of decompression sickness (bends) and nitrogen narcosis. It also lowers your fatigue factor. Nitrox is safer for older divers (40+). Geezer Gas
Communications Underwater communication Before you Dive: Review your hand signals Plan your dive, dive your plan Do not deviate from what you have planned Time and depth are critical Written communication Slates Do not loose track of time/position while you are writing. In current you can drift far away in just a few seconds
Equipment Considerations Depending upon the actual depth, a tank of larger than normal capacity maybe desired. For dives on a coral reef to 130 feet, the average diver will need at least a standard 80 cubic foot tank. All divers MUST have an octopus regulator. Each buddy MUST know the equipment configuration of their buddy.
Equipment Considerations Divers using wet suits MUST take into consideration the compression of the suit and the added negative buoyancy that will result. Even a 2mm shorty will compress and the weight added to compensate for this suit will gradually make you more negative as you descend. When you start your ascent, you will have to vent the air that your added to your BC to compensate for the suit compression. You are also going to gain buoyancy from the expansion of the wetsuit cells to their original size. If you do not pay attention to this change in buoyancy, you can end up rocketing to the surface. The deeper you dive, the more you have to THINK!!!
Buoyancy Control The mark of a skilled diver Loss of buoyancy wet suit compression Have only the required amount of weight Never dive over weighted Learn the art of hovering
Buddy System Increases the fun of diving Always know how much air each other has left. The buddy with the lowest amount of air sets the base line for the dive. Agree on a leader for the dive. This can rotate on successive dives. Know your buddy. If you are uncomfortable with a buddy that has been assigned to you, ask for another buddy or skip the dive. ALWAYS TRAVEL WITH A BUDDY. YOUR BEST BET IS TO TRAVEL WITH A GOOD DIVE GROUP!
Deep Diving Emotional Status Diving is not an activity for an emotionally unstable person. Individuals who tend to lose control or panic in times of crisis may well find occasion to do so in diving. Health and Fitness Persons in poor health and/or poor physical condition are generally considered to be more susceptible to the emotional and physical stress associated with diving.
Deep Diving Stress and response to stress can be amplified with increased depth. It has also been documented that such individuals are more susceptible to decompression sickness. Persons in poor health should seek the advice of a qualified physician and consider imposing significant limitations on themselves or foregoing scuba diving all together.
Deep Diving continued Training Experience Self discipline
Deep Diving continued Environment Diving companion Equipment
Planning a Deep Dive Dive Site If possible, select a dive site that is protected from heavy wave activity and offers good anchorage. Many popular dive sites, especially shipwrecks, have permanent moorings placed by diving or governmental organizations. If diving from shore, select a site where the planned dive depth is readily accessible within a short swimming distance.
Planning a Deep Dive Environmental Conditions Environmental conditions to consider include the bottom topography, depth, steepness of walls, and presence of caverns. Underwater visibility should be such that divers can easily move freely around the bottom (or shipwreck) and easily locate the ascent line at the end of the dive. The water temperature must be anticipated so the correct type of exposure suit can be worn.
Planning a Deep Dive Equipment Selection The water temperature may be colder at deep depths, and a neoprene wet suit will compress, which reduces its thermal protection and buoyancy. Compensation for significant buoyancy changes will be necessary. It is mandatory that each diver be equipped with a dive timer and depth gauge, or a dive computer.
Planning a Deep Dive Since emergency ascents are more complicated and risky from deeper depths, the availability of an alternate air source (Octopus regulators) is even more important than for shallower dives. Remember: your buddy s octopus regulator will do you no good if you allow yourself to get too far away from your buddy!
Planning a Deep Dive continued Scuba Cylinder selection Cylinder configurations and valves Know your buddy s equipment! Regulator Other equipment
Personnel Your next step is to select personnel, which consists of your dive buddy and your support personnel. When you are selecting a buddy, look for someone who has equal or greater experience. It is a good idea to have made a few shallow dives with this person to ensure good communication and compatibility. You and your buddy will also need to make a mutual commitment to personal preparedness.
Personnel You should be well rested, well nourished, have consumed no alcohol for 24 hours prior to diving, and pre check equipment and procedures. The divemaster generally stays at the surface and supervises all aspects of the diving activity. The dive guide, sometimes referred to as an underwater tour guide, is generally a person familiar with dive sites.
Planning a Deep Dive Profile Some guidelines for planning your dive profile: Check the dive planning mode of your dive computer. Make sure the profile is realistically tailored to the underwater terrain and depth. Select a profile that is feasible, considering the air supply and air consumption rate for both you and your buddy. Take an underwater slate with you, with your primary and contingency profiles written out. Dive your plan. Do the deepest part of your dive first, and move progressively shallower as the dive progresses. Allow both time and sufficient air to make a slow, controlled ascent with safety stops. A good practice is to plan your turn around and return to your ascent point at one half your starting cylinder pressure plus 300 PSI
Planning a Deep Dive Profile Planning your dive profile should involve a little more thinking than just choosing a time and depth. Here are some guidelines: Plan the dive not to exceed the Maximum No decompression Dive Time limits of the NAUI Dive Tables. These time limits are more conservative than the U.S. Navy no decompression limits. If you are using a dive computer, you may be able to make a multi level dive that is longer than the square wave time limits. Check the dive planning mode of your dive computer.
Planning a Deep Dive Profile Make sure the profile is realistically tailored to the underwater terrain and depth. Select a profile that is feasible, considering the air supply and air consumption rate for both you and your buddy. Take an underwater slate with you, with your primary and contingency profiles written out. Dive your plan. Do the deepest part of your dive first, and move progressively shallower as the dive progresses.
Planning a Deep Dive Profile Allow both time and sufficient air to make a slow, controlled ascent with safety stops. A good practice is to plan your turn around and return to your ascent point at one half your starting cylinder pressure plus 300 psi.
Gas Management Estimating how long the air supply will last is done with the SAC (Surface Air Consumption) Calculator Emergency procedures considerations Plan for safety stops and the rule of halves if possible
Potential Hazards When, for various reasons, things do not go according to plan during a deep dive, you need to be prepared to deal with any problems that occur. Effects of Increased Pressure The obvious effects of increased pressure are that increased exposure to higher ppn2 can cause decompression sickness and/or narcosis (covered in detail in Physiology chapter).
Potential Hazards The risk of decompression sickness will be minimized greatly by staying above 24.2 m (80 ft) and planning your dives conservatively to remain well within the no decompression limits. Bounce dives, which are successive, relatively short up and down dives, are to be discouraged, as they apparently favor bubble formation. Most decompression experts suggest at least a one hour surface interval between dives.
Potential Hazards Insufficient experience is a major factor in diver distress situations for deep diving. Increased Stress: there is an increased amount of stress on divers during deep dives. Increased stress build up can result in both mental and perceptual narrowing.
The Deep Dive Assemble and check equipment Suit up Final briefing
The Deep Dive continued Dive support station Deployment Descent and buoyancy control
The Deep Dive continued On the Bottom: Approach the bottom cautiously and do not stir up the silt. If the boat's anchor line is used for descent, the first team should check and, if necessary, reposition the anchor. If operating from a large vessel, a crew member will often check and secure the anchor.
Ascent: The Deep Dive continued Ascend as a buddy team, facing each other with one hand on the ascent line. Discharge air from the BCD (and/or dry suit) as needed and remain neutrally buoyant throughout ascent. Some divers use slight positive buoyancy and do not even kick as they ascend the line.
The Deep Dive continued Safety or Decompression Stop: Non technical recreational divers are to avoid exceeding the no decompression limits for the maximum depth of any dive. During ascent from any dive, divers are encouraged to make a safety stop at 5 m (15 ft) for 3 to 5 minutes. This is essential when ascending from a nodecompression deep dive. Allow for the Rule of Halves if possible.
Rule of Halves When ending any no decompression dive in excess of 40 feet, halve the distance from the dive s deepest depth to the surface. Ascend to that depth and make a one minute safety stop. Then continue your ascent to the 15 foot safety stop and complete the last two minutes of your three minute safety stop at 15 feet.
The Deep Dive continued Exit and Post Dive Activity Upon completion of the safety stop, divers should ascend slowly to the surface. Remember that it should take at least 30 seconds to ascend from the stop (a depth only 1 m [3 ft] deeper that the average pool). Persons returning from a deep dive should not be required to manually retrieve the anchor or descent ascent line bottom weight.