Date post: | 18-Dec-2015 |
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Recreational or Deco?
• Recreational limits say stay within no decompression time limit (NDL)
• You can go straight back to the surface unless you’re within 3 pressure groups of the NDL (grey areas of RDP) or below 30m
• The safety stop is just that!
• 24m dive on Air NDL = 29 mins
• 24m dive on EANx32 NDL = 50 mins
What happens if I stay beyond NDL?• You NEED to do COMPULSORY stops• You can no longer go straight to the surface• You have nitrogen bubble build up• You need to monitor OTU’s• You NEED a DECO plan• You need to know what depths to stop at and for
how long• You NEED to know what those flashy computers
actually mean• YOU NEED ENOUGH GAS
RECREATIONAL AIR DIVE with deco
4 mins left for NO DECO
40 mins @ 24m followed by 11 mins @13m, then 3m until clear to surface
15L twinset
DECO
NO DEC TIME changes to ASC TIME
CEILING tells you where you SHOULD be now!!! to allow deco to count DOWN not UP!!
Ascent time means minimumtime before you can surface
Keep an eye on dive time and ASC time!
10 mins extra at 24 m causes 10 MORE mins of DECO
Some computers place an upward pointing arrow here
3m “ceiling”
“floor”
Not a problem if you’re carrying enough gas!!
Current depth
OK so we’ve taken 1 min to go up 11m and lost 1 min deco time
Off-gassing
floor
ceiling
DEEP STOP for 1 minute(optional)
11 mins at this depth but no loss in deco time? Why?
Well, you’re still on-gassing at the same time that you’re off-gassing !!
Usual stops can be 12m, 9m, 6m and 3m
Hourglass symbol appears when you are in the zone Ceiling
Floor
zone
Zone is above the floor and below the ceiling
Means that you are above the ceiling – DESCEND IMMEDIATELY
NOW A NO DECOMPRESSION DIVE AGAIN
Some conservative computers add on a normal safety stop at this point
This will only stay NDL if you do not go below this 3m floor, otherwise you’re in DECO again!!
13 secs of DEEPSTOP left
89 mins ASC TIME
48m ceiling.. a deco stop.In 13 secs next ceiling or decoappears
Current depth slightly deeper than ceiling
In the zone… hourglass
Now do you know yours?
• Remember.. If you’re going into deco, make sure that you have ample gas
• Split your main gas into thirds – One third in– One third out and– One third remains for that emergency
• Deco gas is split in half– Half used, half kept in reserve
Deco Disadvantages
• Its boring
• Its cold
• Need lots of gas in reserve
• Double up on kit in case of failures
• Its cold!!
• Its boring!