Chapter Four is divided into five sections:
1. Dive Accessories
2. Health for Diving
3. Breathing Air at Depth
4. Dive Tables and Dive Computers (Introduction)
5. Confined Water Dive Preview
Here are Summary Points from Chapter Four on Dive Accessories:
* You use a surface float to support your dive flag, for resting and to carry accessories.
* Use an appropriate dive flag when diving where boats may be present and according to local law.
* Don't attach a full collecting bag to your gear.
* Underwater lights have both day and night uses.
* A spare-parts kit can help you from missing a dive.
* Start and maintain a log of all your dive adventures.
* To communicate with an underwater slate, you have to have one.
Here are Summary Points from Chapter Four on Health for Diving:
* Don't drink, smoke or take drugs before diving.
* Don't dive when you don't feel well.
* Stay in good health.
* Have a physical examination at least every two years.
* Keep tetanus and typhoid immunizations current.
* Pregnant women should NOT dive.
* Review your dive skills and knowledge after a period of inactivity.
Here are Summary Points from Chapter Four on Breathing Air at Depth:
* Air is 79 % nitrogen and 21 % oxygen.
* Contaminated air symptoms include headaches, nausea, dizziness, unconsciousness, and cherry red lips and nail beds.
* Don't have your tank filled with oxygen, and don't use enriched air unless certified in its use.
* To avoid nitrogen narcosis, avoid deep dives.
* Decompression sickness is caused by excess nitrogen forming bubbles in the body after a dive.
*
Stay well within dive table and dive computer limits, especially if secondary factors apply to you.
* Signs & symptoms of DCS include limb & joint pain, tingling, numbness, paralysis, shock, weakness, dizziness, difficulty breathing, unconsciousness and death.
* Decompression Illness (DCI) is a clinical term for BOTH decompression sickness and lung over expansion injuries.
* A diver with DCI should receive emergency oxygen, rescue breathing and CPR if necessary, and will require treatment in a decompression chamber.
Here are Summary Points from Chapter Four on Dive Tables& Dive Computers Introduction:
* Dive tables& dive computers use mathematical models to estimate the theoretical nitrogen in your body before, during and after a dive.
* People vary in their susceptibility to DCS, so no computer or table can guarantee you'll never get DCS, even within its limits. So, dive well within table/computer limits.
* A dive computer has some use advantages and disadvantages compared to tables, but it is neither more nor less valid.
* Recreational divers only make no decompression (no stop) dives.
* The RDP is the most popular recreational dive table, and it is the first one developed and tested exclusively for recreational diving.
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The wheel and dive computers offer you more no decompression dive time when making multilevel dives.
* You must account for nitrogen you absorb on a dive if you make a repetitive dive before your nitrogen levels return to normal.
* Stay within the depth limit of your training and/or experience. Generally: Scuba Divers - 12m/40 ft.;Open Water Divers - 18m/60 ft; General Recreational limit - 30m/100 ft.; Max. limit - 40m/130 ft.
* Be a SAFE Diver: Slowly Ascend From Every Dive.
Confined Water Dive Four Skill Requirements:
Skin Diving Skills
1.Demonstrate the use of proper hyperventilation when skin diving.
2.Dive vertically headfirst from the surface in water too deep to stand up in (without excessive splashing or arm movement).
3.Clear and breathe from a snorkel upon ascent.
Scuba Skills
4. Swim underwater without a mask for a distance of not less than 15 metres/50 feet, and replace and clear the mask underwater.
5.
Using buoyancy control only, hover without kicking or sculling for at least 30 seconds.
6. Buddy breathe sharing a single air source for a distance of at least 15 metres/50 feet underwater both as a donor and a receiver. (optional skill)
