4_3_3

Report
Repetitive Dive
Surface Interval
Cold, Arduous Dive
Dive Computers
Safety Stop
Dive Tables
Decompression Theory
Residual Nitrogen
Bottom Time
No Decompression Limit
Dedicated to the advancement and practice of scientific diving
Nitrogen Absorption
Outgas
Residual
N2
Final Level
N2
N2
Surface Interval
Dive 2
Dive 1
Additional
Absorbed
Absorbed
N2
Residual
N2
Dedicated to the advancement and practice of scientific diving
N2
Revolving Charge Account
Purchase Table
0
100
200
Outstanding 300
Balance
400
500
600
700
800
900
100 200 300 400 500 600 700 800 900 1000
A B C D E F G H I
J
1
A
B
C
D
E
F
G
H
I
2
1
3
2
1
4
3
2
1
5
4
3
2
1
6
5
4
3
2
1
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
10
9
8
7
6
5
4
3
2
1
Credit Rating
Terms:
Limit - $1,000
$100 Increments
$100 Repay Inc
Repay Weekly
Repayment Table
New Credit Rating
Dedicated to the advancement and practice of scientific diving
History of Decompression Sickness
(DCS)
• 1837 first described after hard hat salvage
operation (symptoms were attributed to cold
water)
• Caisson workers in the late 1800’s
• 1900 Haldane commissioned by British
Admirality to study and solve problem of DCS
Dedicated to the advancement and practice of scientific diving
Development of Dive Tables
• Haldane conducted saturation experiments with
animals
• Established a 2:1 pressure ratio (half times)
• Four factors involved in N2 absorption
–
–
–
–
Pressure gradient
Tissues absorb at different rate
Blood flow is not equal to all parts of the body
Tissue half times
» 5 - 10 - 20 - 40 - 60
Dedicated to the advancement and practice of scientific diving
DCS Risk factors
•
•
•
•
•
•
•
•
•
•
Deep dives
Repetitive dives
Multi-day diving
Fatigue
Dehydration
Age
Temperature
Exertion
Decompression diving
Rapid ascent
Dedicated to the advancement and practice of scientific diving
Dive Tables
Dive Planning and
Scheduling Tool
• Depth
• Time
• Repetition
Types of Dives
No Stop Required
on Ascent
Mandatory
Stop on
Ascent
No Decompression
Repetitive
Decompression
Dedicated to the advancement and practice of scientific diving
DCIEM Dive Tables Terminology
End of Dive
Repet Group
(RG) Letter
Repet Dive SI
10 min - 12 hrs
Surface Interval Time (SI)
( : )
Safety
Stop
15’-25’
Depth
Before Dive
Repet Factor (RF)
( : )
Safety
Stop
15’-25’
Safety
Stop
15’-25’
NDL
BT
Dive 1
Dive 2
ABT
Actual bottom time
ABT
Residual Nitrogen Time (RNT)
= No-D Limit(NDL)
- Residual No-D Limit (RNDL)
Dive 3
ABT
RNT = NDL - RNDL
EBT = ABT + RNT
Effective Bottom Time (EBT) = ABT + RNT
•EBT Must Be Less Than or Equal to RNDL
•The RG for each repetitive dive must be greater than that of the preceding dive
•After 3 days of repetitive diving, a day off is recommended
Dedicated to the advancement and practice of scientific diving
Dedicated to the advancement and practice of scientific diving
Dive 1
87 Feet for 17 Minutes
Repetitive Group (RG) Letter
D
Dedicated to the advancement and practice of scientific diving
Surface Interval (SI)
2:00
D
1.3
Repetitive Factor
(RF)
Dedicated to the advancement and practice of scientific diving
Repetitive Dive
Planning
D
87’/17min
(SI)2:00
1.3
65 ft
Repetitive No-D Limit
RNDL = 21
Residual Nitrogen Time (RNT)
RNT = NDL - RNDL
= 35 - 21
= 14 min
Dedicated to the advancement and practice of scientific diving
Repetitive Dive
D
87’/17min
(SI)2:00
1.3 E
65 ft
ABT = 19 min
Repetitive No-D Limit
RNDL = 21
Residual Nitrogen Time (RNT)
RNT = NDL - RNDL
= 35 - 21
= 14 min
Effective Bottom Time (EBT)
EBT = ABT + RNT
= 19 + 14
= 33 min Dedicated to the advancement and practice of scientific diving
Repetitive Factor
D
87’/17min
(SI)2:00
(SI) 3:00
1.3 E
1.3
65 ft
ABT = 19 min
Dedicated to the advancement and practice of scientific diving
Repetitive Dive
Planning
D
87’/17min
(SI)2:00
(SI) 3:00
1.3 E
1.3
45 ft
65 ft
ABT = 19 min
Repetitive No-D Limit
RNDL = 50
Residual Nitrogen Time (RNT)
RNT = NDL - RNDL
= 75 - 50
= 25 min
Dedicated to the advancement and practice of scientific diving
Repetitive Dive
D
87’/17min
(SI)2:00
(SI) 3:00
1.3 E
1.3
G
45 ft
65 ft
ABT = 45 min
ABT = 19 min
Repetitive No-D Limit
RNDL = 50
Residual Nitrogen Time (RNT)
RNT = NDL - RNDL
= 75 - 50
= 25 min
Effective Bottom Time (EBT)
EBT = ABT + RNT
= 45 + 25
= 70 min Dedicated to the advancement and practice of scientific diving
Dive Computers
• The use of electronic dive computers to permit
multi-level diving is permissible, but only if such
instruments are used strictly according to the
manufacturer’s instructions and recommendations
and only for no-decompression diving.
• Computers should be monitored and the dive
controlled in a manner that will permit a direct
ascent to the surface at any time.
Dedicated to the advancement and practice of scientific diving
Safe Dive Practices
Do not push tables/computer
to limits
Surface Intervals
1 hour minimum, longer is
better
Dedicated to the advancement and practice of scientific diving
Safe Dive Practices
Slow Ascent Rates
Ascent rates shall be controlled at 30 fsw/min
from 60’ and not exceed 60 fsw/min from depth.
Reference:
Lang, M.A. and R.W. Hamilton (eds.). 1989. Proc. of the AAUS Dive
Computer Workshop. USC Catalina Marine Science Center. USC
Sea Grant Publ. USCSG-TR-01-89. 231 p.
Lang, M.A. and G.H. Egstrom (eds.). 1990. Proc. of the AAUS
Biomechanics of Safe Ascents Workshop. Woods Hole, MA.
American Academy of Underwater Sciences Publ. AAUSDSP-BSA01-90. 220p.
Dedicated to the advancement and practice of scientific diving
Safe Dive Practices
Safety Stops
A stop in the 10-30 fsw zone for 3-5 minutes is
required on every dive.
Reference:
Lang, M.A. and R.W. Hamilton (eds.). 1989. Proc. of the AAUS Dive
Computer Workshop. USC Catalina Marine Science Center. USC
Sea Grant Publ. USCSG-TR-01-89. 231 p.
Lang, M.A. and G.H. Egstrom (eds.). 1990. Proc. of the AAUS
Biomechanics of Safe Ascents Workshop. Woods Hole, MA.
American Academy of Underwater Sciences Publ. AAUSDSP-BSA01-90. 220p.
Dedicated to the advancement and practice of scientific diving
Flying after diving
Divers should have a minimum surface interval of 12
hours before ascending to altitude.
Dedicated to the advancement and practice of scientific diving
Summary
Safety
•
•
•
•
•
•
•
•
Don’t “Push” Tables
S.A.F.E. Dive
Safety Stops
Deepest Dive First
Multi-Day, Multi-Dives
Cold, Arduous Dive
Flying After Diving
High Altitude Diving
Emergency
Procedures
• NDL Inadvertently
Exceeded
• Cease Diving
• Observe for DCS
•If DCS Symptoms appear
• Administer 100% Oxygen
• Evacuate
Don’t Make The $30,000 Mistake
Dedicated to the advancement and practice of scientific diving

similar documents