Unit 5
Unit 5- Technical Dive Planning
Technical
Dive Planning
Student Performance
By the end of this lesson you will be able to:
Unit 5- Technical Dive Planning
Describe:
– Team Diving
– Surface Consumption Rate Calculations
– NAUI Dive Planner
– Best Mix
– OCEANx Calculator
– Dive Planning
Dive Plan Considerations
Unit 5- Technical Dive Planning
Maximum depth
Bottom time
Back (bottom) gas
mix
– Narcotic depth
– Oxygen exposure
Decompression gas
Decompression
schedule
Gas management
Environmental
Support
What if?
The Participants
Unit 5- Technical Dive Planning
Boat captain
First mate
Team leader
Dive leader
Crew members
Team members
Subordinates
Observers
Buddy system
Rules and Regulations
Unit 5- Technical Dive Planning
Rules and regulations that can affect dive
planning come from many sources:
– Boat
– Local
– State
– National
– Certification agency
Team Members
Unit 5- Technical Dive Planning
Push team
In-water support
Topside support
Topside supervisor
Emergency responders
Push Team
Unit 5- Technical Dive Planning
Most extreme exposure
Dive in team pairs (Buddy)
Similar training
Similar abilities
Same objective
Same configuration (NTEC)
Same gas and plan
In-water Support
Technical Support
Leader
– First responder
Unit 5- Technical Dive Planning
–
–
–
–
–
Shuttle gas
Shuttle gear
No deco obligation
Full tech diver capability
Same gear configuration
First Responders
Most Valuable Part of the Team
Unit 5- Technical Dive Planning
Surface Support
Unit 5- Technical Dive Planning
Another important part of the team!
– Qualified personnel
– Sufficient gear and gas
Equipment technician
– Fully able to care for
all equipment
– Gear check list
– SPARE PARTS!!!!
– On-site repairs
Surface Support continued
Unit 5- Technical Dive Planning
Medical officer
– First aid supplies
– Oxygen
Dive supervisor
– Communications
equipment
– Written
emergency plan
– Diver plans
– Team plans
Surface Support continued
Dive supervisor
(continued)
Unit 5- Technical Dive Planning
Gas selection and
requirements
–
–
–
–
–
–
–
Bottom mix
Bailout mix
Deco gas
Surface supplied gas
Stage gas
Insulation gas
Treatment gas
Preparing for the Worst
Unit 5- Technical Dive Planning
Accident Analysis
Common Crises
Potential Problems
Solution Scenarios
Gas Consumption (Imperial)
SCR Formula (imperial):
Unit 5- Technical Dive Planning
Calculate the SCR for a diver who uses 375 psi
from a standard 80 ft3 cylinder while breathing
normally for 10 minutes at 33 fsw.
 cyl. pres. 
 psig 
 time 
 minutes 
SCR =
OR
= (psi/min)/ata
pres. abs.
ata
 375 psi 
 10 min 
 = 18.75 (psi/min)/ata
SCR (at rest) = 
2 ata
Resting SCR is at static deco
Working SCR is while actively swimming
Gas Consumption (Metric)
SCR Formula (metric):
Unit 5- Technical Dive Planning
Calculate the SCR for a diver who uses 22 bar
from a 12 L / 200 bar cylinder while breathing
normally for 10 minutes at 10 msw.
 cyl. pres. 
 bar 
 time 
 minutes 
SCR =
OR
= (bar/min)/ata
time
ata
 22 bar 
10 min 
SCR (at rest) =
= 1.1 (bar/min)/ata
2 ata
Resting SCR is at static deco
Working SCR is while actively swimming
Cylinder Supply Time
For any SCR we can calculate the
approximate time a cylinder will last at
any depth.
Unit 5- Technical Dive Planning
Cylinder supply time at depth =
(cylinder pressure / SCR) ÷ absolute pressure
SCR in Volume Formula
Converting SCR in pressure to SCR in
volume
Unit 5- Technical Dive Planning
SCR volume =
rated cylinder capacity x SCR pressure
rated cylinder pressure
Cylinder Pressure per Volume
With U.S. cylinders it is sometimes useful
to know the pressure per unit volume of
delivered gas (at 1 ata).
–
Unit 5- Technical Dive Planning
–
U.S. cylinders are rated by service pressure
and gas capacity.
The pressure per volume is equal to the rated
pressure divided by the rated capacity.
–
Example: A cylinder that contains 80 ft3 of gas at
3000 psi has a pressure per volume of 37.5 psi per
ft3.
Note: Metric cylinders are classified by service
pressure and actual cylinder volume (or “wet”
volume).
Example: A 240 bar, 10.5 liter cylinder contains 2520
liters of gas when fully charged.
Gas Management Rules
Rule of Halves
Unit 5- Technical Dive Planning
( starting pressure - residual pressure) 
Turn pressure = starting pressure - 

2


Rule of Thirds
( starting pressure - residual pressure) 
Turn pressure = starting pressure - 

3


Best Mix Formula
Unit 5- Technical Dive Planning
NAUI recommends limiting the partial
pressure of oxygen to 1.4 ata maximum.
“Best mix” is the maximum oxygen
fraction that will not exceed the PO2 limit.
To calculate best mix, use
PO2
FO2=
P
Where PO2 is 1.4 ata
and
P is the absolute pressure at
depth
Oxygen Dose Formula
The oxygen dose a diver receives at
depth depends on the exposure time
and the partial pressure of oxygen.
Unit 5- Technical Dive Planning
PO2 = FO2 × P
NOAA Oxygen Limits
Maximum
Maximum
PO2 atm Single Limit 24-Hour Limit
1.60
1.50
1.40
1.30
1.20
45
120
150
180
210
150
180
180
210
240
The deeper / longer you dive, good practice is to lower
the PO2 vs. dive time exposures and OTL/OTU limits
Dose, Mix, Depth
(Dose)
PO2
Unit 5- Technical Dive Planning
FO2
(Mix)
Pata
(Depth)
x
÷
Equivalent Narcosis Depth
END = [1 – (FO2+FHe) · (Depth + 33 fsw)] – 33 fsw
0.79
Unit 5- Technical Dive Planning
END = (1 – (FO2+FHe) · (Depth + 10 msw)] – 10 msw
0.79
33 fsw or 10 msw is equivalent of one atmosphere of
pressure expressed in feet of seawater or meters of
seawater
Question: What is the END for a diver using helitrox
(26/17) at a depth of 138 fsw (42 msw)?
Equivalent Narcosis Depth continued
Is oxygen considered to be narcotic?
Unit 5- Technical Dive Planning
OCEANx
Calculator
Unit 5- Technical Dive Planning
OCEANx provides:
–EAD
–PO2
–FO2
–PO2 Time Limits
–OTUs
–O2 Time Limits
OCEANx
Calculator continued
Using the OCEANx to find the EAD
(Partial values are rounded up to the next whole value for safety)
32%
AD
fsw
40
50
60
70
80
90
100
110
120
130
140
150
160
170
EAD
fsw
Exposure Index
Use EAD with an air dive table
51
63
75
86
98
109
121
132
EAD = Equivalent Air Depth (fsw)
Unit 5- Technical Dive Planning
AD = Actual depths
O2 %
NOAA O2 LIMITS
OTL
min.s
300
240
210
180
150
120
45
AD
fsw
70
80
90
101
111
121
132
PO2
ata
1.0
1.1
1.2
1.3
1.4
1.5
1.6
% O2
OTU
per
min.
0.33
0.42
0.48
0.56
0.67
0.83
2.22
per
min.
1.00
1.16
1.32
1.48
1.63
1.78
1.92
NAUI Dive Planner (Imperial)
Unit 5- Technical Dive Planning
NAUI Dive Planner (Metric)
Unit 5- Technical Dive Planning
Calculating O2 Exposures
Unit 5- Technical Dive Planning
Use The OCEANx calculator
The math is easy, too
(Time at Depth / NOAA Limit) X 100%
NOAA Oxygen Limits
Maximum
Maximum
PO2 atm Single Limit 24-Hour Limit
1.60
1.55
1.50
1.45
1.40
1.35
1.30
1.25
1.20
45
83
120
135
150
165
180
195
210
150
165
180
180
180
195
210
225
240
%O2 Exposure & OTU
Unit 5- Technical Dive Planning
Gas Requirements
Unit 5- Technical Dive Planning
Gas Demand = minutes x ata x SCR
Gas Reserve = (Gas Demand) / 2
Total Requirement for Thirds (w/o residual)
= Gas Reserve x 3
Total Gas Requirements
Unit 5- Technical Dive Planning
Residual Oxygen Percent Table
Unit 5- Technical Dive Planning
Repetitive Dive Profile
Unit 5- Technical Dive Planning
Run Time
The cumulated chronological elapsed
time at each phase of the dive.
–
Unit 5- Technical Dive Planning
The time from the start of the dive to
leaving the bottom plus ascent time plus
stop times.
Cumulative run time is listed at each
depth on the dive planner.
Decompressing on Oxygen
Unit 5- Technical Dive Planning
When decompressing on Enriched Air Nitrox,
it is important to monitor oxygen exposures
to stay within established limits.
When decompressing on 100% oxygen, it is
vital to monitor oxygen exposure, depth, and
time.
If decompressing on 100% oxygen, a fiveminute back gas break must be taken at least
every 20 minutes.
– Break does not count toward deco time.
Repetitive Dives
Unit 5- Technical Dive Planning
Minimum 3 hour surface interval is
required with RGBM decompression
tables.
Maximum of one repetitive dive after an
initial decompression dive with RGBM
decompression tables.
Must track OTUs.
With deep RGBM tables, diver switches to
oxygen at 6 msw/20 fsw.
Planning Repetitive Dives
Unit 5- Technical Dive Planning
Plan the following two dives and write your
answers on a NAUI Dive Planner.
– Dive 1 is to 50 msw/165 fsw for 20 minutes
bottom time.
– Dive 2 is to 33 msw/110 fsw for 15 minutes
bottom time.
– Use the RGBM 16/24 for the first dive. Use
a 3 hour surface interval. Compute dive 2
on helitrox (26/17). Compute all oxygen
exposure limits and totals. Calculate gas
requirements and compute totals based on
thirds.
Dive 1 (Imperial)
Unit 5- Technical Dive Planning
Repetitive Dive (Imperial)
Unit 5- Technical Dive Planning
Dive 1 (Metric)
Unit 5- Technical Dive Planning
Repetitive Dive (Metric)
Unit 5- Technical Dive Planning
Contingency Planning
Unit 5- Technical Dive Planning
First is dive schedule
Alternate schedules
– Deeper depth
– Longer time
Bailout schedule
Write it down
Student Performance
By the end of the lesson students will be able to:
Unit 5- Technical Dive Planning
Describe:
– Describe team diving
– Perform SCR Calculations
– Use the NAUI Dive Planner
– Describe and determine best mix
– Use the OCEANx Calculator
– Plan dives