Sports Diver Lectures Flashcards
Describe the course content for SD.
6 theory lessons 1 sheltered water lesson 5 open water lessons 1 dry practical lesson Experience 5 different conditions
Who can SD dive with and what limitations?
OD - in conditions encountered by OD during training or under supervision from DM
SD - in conditions encountered previously
DL - under supervision of NQI
Can dive to 20m but can be progressively extended under NQI
Describe what a spring and a neap is.
Moon and Sun’s gravity pulls ocean towards them - bulge of high water
When both lined up -Spring
When at 90’ - Neap
How long is a tide cycle and how long is a lunar month?
Cycle = 12 hours Month = 28 days
What is the tidal range?
Difference between high and low water
What reduces visibility?
Waves Plankton blooms Currents Seabed disturbed Depth - reduction in light penetration
What are the potential problems we need to risk assess?
Breathing gas eg loss, depletion
Conditions eg cold, separation
Depth eg DCI, narcosis
Equipment eg faulty, new
How many RB do you give at surface?
10 (for 1 minute)
How to land casualty on shore or boat?
Continue RB for a further 1 minute in water
De-kit and land asap without further RB
How to do BLS?
30 compressions then 2 rescue breaths if 1 rescuer
If 2, change role every 2 minutes
Press down 4-5cm at 100 times/min
How can we use a shot line to aid decompression?
Back up deco cylinder can be attached to line
Lazy shot line can be attached
Decompression trapeze
What are the types of SMBs?
SMB -permanent marker
DSMB - deployed from underwater to indicate ascent location
Describe structure of SMB - how much weight can the surface float support and how long must the line be?
Surface float - supports 10-20kg
Line length = 1.25 times dive depth
What are the types of DSMB?
Self inflating - simply to deploy, expensive
Open ended DSMB - compact, have to manually inflate
Self-sealing DSMB
Colours of DSMB
Orange/ red = normal
Yellow = emergency
What is Dalton’s Law?
In a mix of gases, total pressure = sum of partial pressures
What is FO2?
Fraction of oxygen in mix
= %O2 divided by 100
eg FO2 of Nitrox 36 = 36/100 = 0.36
What is max recommended pO2?
1.4 bar
How do you work out MOD?
Max pO2 / mix
eg 1.4 / 0.32 = 4.38 bar = 33.8m
What can narcosis increase the effect of?
Anxiety Alcohol or medication Increased physical effort Cold water Poor vis Rapid descent
What is hyperoxia and what bar do we get O2 toxicity?
Too much oxygen
Whole body oxygen toxicity when pO2 >0.5bar for long time OR CNS toxicity when pO2 >1.4bar for short periods
Causes of CNS toxicity?
Failure to analyse mix/ mark cylinders
Poor dive planning
S&S of CNS toxicity?
Visual/ auditory disturbances
Dizziness, nausea
Irritability
Twitching, convulsions
Phases of CNS convulsions?
Tonic - do not lift - casualty becomes rigid and holds breath
Clonic - do not lift - casualty has convulsion
Relaxation phase - lift - relaxes and is unconscious
How to prevent CNS toxicity?
Avoid high CO2 levels
Don’t over exercise
Breathe normally
Don’t exceed 1.4bar/ MOD
How do we monitor O2 exposure?
O2 Toxicity Tables
CNS% should not exceed 80%
While at surface CNS% is reduced by half every 2 hours
Add outstanding CNS% to next dive
What is a decompression stop dive?
Where tables indicate need for stop
Surface Code G
What is a decompression stop?
Time spent at stop (9m or 6m)
What is the advisable limit for decompression stops in 24 hours?
20 mins
What is the average SAC?
25L/min
How do you work out how much air you need for a dive?
25l/min x absolute pressure x time
How do you work out cylinder capacity?
Size of cylinder x bar pressure
What is the MOD for Nitrox 32 and 36?
32 = 35m 36 = 30m
What is a SCR?
Semi-closed Circuit Rebreather
Pre-selected gas mix
MOD determined by mix
Excess gas vented off
What is a CCR?
2 cylinders, O2 and air
Electronically controlled
