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35 Cards in this Set
- Front
- Back
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What are the best prerequisites for a person who wishes to engage in snorkelling?
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* good health
* be a good swimmer *necessary equipment * dive with a partner *good general knowledge |
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Why is ‘safety’ glass or ‘tempered ‘glass preferred in dive masks?
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to guard against breakage or scratching
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What is the ‘Sniff’ Test?
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put mask on your face without straps, and inhale gently through your knows. If the mask is a good fit it will cling to the face
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What is the difference between a SINGLE LENS dive mask and a SPLIT LENS dive mask?
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* single lens mask has only one plate and may suit some faces better.
* split lens have to lenses and have a lower volume. |
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What are the advantages of a SPLIT LENS dive mask over a SINGLE LENS dive mask?
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* easier to clean and easier to see
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Explain how a dive mask is cleared of water while the snorkeller is underwater.
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tilt your head back and blow air though your nose.
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On what side of the dive mask should the snorkel be attached?
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left side
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List the different types of fins available in snorkelling
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*open healed fins
*full booted fins |
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Describe the advantages and disadvantages of each type of fin available in snorkelling.
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Open heeled fins – require wet suit booties, good for snorkelling in rocky areas
Full booted fins – good for entries made from vessels |
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Why is the size of the bore of a snorkel important to divers?
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Because snorkels with a large bore size require more air so are used by people with larger lung capacities.
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What features are best when choosing a snorkel?
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Length of 30-40cm, diameter of 2cm, top 5-7cm brightly coloured
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List the advantages of using a Wetsuit while snorkelling
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Protects body from cuts, abrasions, stings bruises and sunburn. Keeps you warm, act to help buoyancy, reduce hypothermia.
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List the 3 ways a snorkeller can enter the water
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Giant stride
Roll entry Push off |
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name the parts of the ear
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name the parts of the eye
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Why do snorkellers equalise while descending during a dive?
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to prevent pressure build up on the inside of the ear causing great pain
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What happens to the human eardrum during a diving descent?
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pressure increases on the eardrum
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List at least 3 ways a snorkeller can equalise during a dive.
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Pinching your nose and blowing gently
Turn your head Air can be blown from the mouth |
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How do objects appear to divers underwater?
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things will appear blurred range of visibility and intensity of colour decrease
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What type of flag is used to mark a dive site for snorkellers?
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what is shallow water blackout
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snorkeller becomes conciousness, usually whilst returning to the surface. it is caused by low oxygen levels as a result of hyperventilating before a breath hold dive
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From what part of the Ear does the sensation of Seasickness originate?
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Semicircular canals that are responsible for balance and if disturbed can induce sea sickness
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what are the rescue techniques from low to high risk
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Reach, Throw, Wade, Row, Swim, Tow
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Why is it difficult to determine the direction a sound is coming from underwater?
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Time delay, sound reaches one ear before the other
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What is the percentage concentration of Oxygen and Nitrogen in the air?
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21% oxygen 78% Nitrogen
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Describe the correct method to ascend from a dive when snorkelling.
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Spiral three sixty
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how is hypothermia caused
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when the body's temperature drops to the point it cannot be recovered
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what is a snorkelling vest
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allows you to relax on the surface while being positively buoyant
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how does a face mask help while snorkelling
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the rays of light enter the eye normally and the image is clear, but mask has magnifying effect and objects appear closer and bigger.
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what colours penetrate different depths
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what is salt-water aspiration syndrome
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rare disorder suffered by snorkellers who inhale a mist of sea water. it can affect asthma suffers causing shortness of breath aches and pains or a mild fever
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problems that can develop in the outer ear in snorkelling
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top of the pinna can get sun burnt
wax can build up with age and impair hearing bacteria can cause an outer ear infection the eardrum can be damaged by pressure |
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how many times faster does sound travel in water than in air
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4 times
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what is Archimedes principle
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when an object is immersed in water it would displace a volume of water whose mass is equal to the upthrust
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what are 3 ways of clearing a snorkel
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blast method - once snorkel is filled with water take head out of the water and blow air out
displacement method - surface at an angle and blow a small amount of air masks with purge valves - breath out through nose and force water out of mask via the valve |
