Transcript Dive Planning

Dive Planning
Sources
• Barsky, S.M. 1999. Diving in High-Risk Environments.
Hammerhead Press, Santa Barbara, CA. 198 pp.
• Joiner, J.T. 2001. NOAA Diving Manual: Diving for
Science and Technology. Best Publishing Co., Flagstaff,
AZ.
• US Department of the Navy. 1999. US Navy Diving
Manual. Revision 4. NAVSEA 0910-LP-708-8000. Naval
/sea Systems Command, 2531 Jefferson Davis Hwy,
Arlington, VA.
Objectives
• Upon completion of this module, the participant
will be able to:
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State the essential elements of a dive plan
State the advantages and disadvantages of breath-hold diving
State the advantages and disadvantages of open-circuit scuba
State the advantages and disadvantages of umbilical-supplied systems
State the advantages and disadvantages of closed-circuit systems
List the responsibilities of NOAA Divemasters
Discuss surface and underwater environmental conditions as applied to
diving
– List common diving signals
Objectives (cont)
• Upon completion of this module, the
participant will be able to:
– Calculate air consumption rates using RMV
– Describe how to determine individual Surface Air Consumption rates
– Describe how to estimate a scuba cylinder duration at depth
The Dive Plan
• Careful planning is the key to an efficient dive operation. The dive
plan should include at least the following:
– Definition of objectives (clear statement of purpose and goals)
– Analysis of pertinent data (e.g., surface conditions, sea state,
temperature, depth, bottom type, tides, currents, visibility, pollution,
hazards)
– Assistance and emergency information, including location, status,
contact procedures for nearest recompression chamber, air evacuation,
US Coast Guard, and nearest hospital
– Diving team selection, including divemaster, medical personnel,
tenders/timekeeper, boat operator and surface personnel
– Diving mode selection, e.g., skin/snorkeling, open-circuit scuba,
rebreathers, surface-supplied, hookah
The Dive Plan (cont.)
– Equipment and supplies selection, such as breathing gas, backup
supply, dive platform, support equipment, oxygen resuscitator, first aid
kit, backboard, dive flag, tools, communications, water
– Schedule of operational tasks, including transit to site, assembling dive
gear and support equipment, predive briefing, calculating allowable
underwater times, recovery, cleaning, inspection, repair, and storage of
gear, debriefing of divers and support personnel
– Final preparations and safety checks, including review of dive plan,
outline of dive assignments and sequence, complete and post onsite
emergency checklist, review divers qualifications and conditions, secure
permission from command or vessel captain for dive
– Briefing/debriefing diving team, including the objective and scope of
the operation, conditions in the operating area, diving techniques and
equipment to be used, personnel assignments, specific assignments for
each diver, anticipated hazards, normal safety precautions, any special
considerations, group discussion period
Selection of Diving Equipment
• Breath-hold Diving Equipment
– Generally used for observation and specimen collections,
photography, or scouting out dive sites in shallow water
– Advantages include: less physical work, simplified logistics,
fewer medical/physiological complications
– Disadvantages include: limited in depth and underwater time
duration, requires breath-holding techniques, useful only in
relatively calm sea conditions
Selection of Diving Equipment (cont.)
• Open-Circuit Scuba
– Generally used for scientific observations, light underwater
work, sample collections, and shallow-water research
– Major advantages include: minimum support requirements,
mobility, accessibility and economy of equipment and breathing
gas, portability, and reliability
– Major disadvantages include: lack of efficient voice
communications, limited depth and duration
Selection of Diving Equipment (cont.)
• Umbilical-Supplied Systems
– Generally used for scientific work, ship inspection and repair,
salvage, long-duration data gathering, harsh environments (low
visibility, strong currents, polluted water)
– Major advantages include: long duration, voice communications,
protection from environment
– Major disadvantages include: limited mobility, significant
support requirements
Selection of Diving Equipment (cont.)
• Closed-Circuit systems
– Generally used for observations of long duration
– Major advantages include: mixed-gas capability, less noise or
bubbles, conservation of breathing medium, long duration
– Major disadvantages include: complicated maintenance,
extensive training requirements, cost of equipment
Dive Team Organization
• NOAA Divemasters have complete responsibility for the safe and
efficient conduct of all NOAA diving operations. Responsibilities
include:
– Preparation of a basic plan of operation, including evacuation and accident
management plans
– Liaison with other organizations
– Inspection of equipment
– Proper maintenance, repair, and stowage of equipment
– Selection, evaluation, and briefing of divers and other personnel
– Monitoring progress of the operation, and updating requirements as necessary
– Maintaining the diving log
– Monitoring of decompression (when required)
– Coordination of boat operations when divers are in the water
Dive Team Organization
• The individual diver is responsible for:
– Being in proper physical condition
– Checking out personal equipment before the dive
– Thoroughly understanding the purposes and
procedures to be used during the dive
– Refusing to dive when conditions are unsafe, when
not in good mental or physical condition, or when
diving would violate their training or applicable
standards
Diving Medical Officer/Diving Medical
Technician
• A Diving Medical Officer or Diving Medical Technician
shall be assigned to all diving operations
• If not available, then these authorities shall be contacted
if required:
– Divers Alert Network (DAN) (919) 684-8111 (ask for the Diving
Physician)
– Navy Experimental Diving Unit (850) 234-4351
– Brooks Air Force Base (210) 536-3278 or (210) 536-3281
Environmental Conditions
• Must be considered when planning a diving operation
• Surface conditions include weather, sea state, and boat
traffic
– Continuous marine weather broadcasts are provided by NOAA
on the following frequencies depending on the local area:
• 162.40 MHz, 162.475 MHz, or 162.55 MHz
• Available from VHF radio or weather radio
Environmental Conditions
• Sea state is generally described on a scale of 0-9, as
depicted in the figure below
• Sea states above 4 (moderate seas) should be avoided
whenever possible
Environmental Conditions
• Diving operations conducted in harbors, rivers, or
shipping channels may pose serious problems
• Display the proper signal flag, shape and lights
Underwater Environmental Conditions
• Diving depth should be determined as accurately as possible
• Dive duration, gas requirements, and decompression schedules should be
planned accordingly
• Mud bottoms often have suspended sediment in the water
• Coral reefs have sharp protuberances - divers need hand and body
protection
• If a current exists, a buoyed safety float line at least 100 ft in length should
be deployed from the stern of the vessel
• Free-swimming descents should be avoided in a current - use a down line
• Begin the dive into the current so it is easier to return to the entry point at
the end of the dive
• Tidal currents should be identified, and if significant, diving should be
done at slack tide
Underwater Environmental Conditions
(cont)
• Water temperature determines the type of exposure suit
to be worn
• A thermocline, which is an abrupt change in
temperature with depth, can occur at any depth, and
should be considered in the dive plan
• If underwater visibility is limited, a buddy line or float is
recommended
• Contaminated or polluted water may have health
hazards
– Detailed procedures are described in another module
Diving Signals
• Hand signals are used to convey basic information
• Some common signals are shown below
– For a complete list see the NOAA Diving Manual
OK! OK?
Distress (need help)
OK! OK?
Diving Signals (cont)
Going
down
Stop
Going
up
OK
Something
Is wrong
OK?
OK!
Help!
Low on air
Out of air
Diving Signals (cont)
Come
here
Go that
way
Me, or
Watch me
I am
cold
Which
Direction?
Slow
down
yes
no
Ear not
clearing
Look
down
Hold
hands
You lead,
I’ll follow
Get with
buddy
What time,
What depth?
I don’t
understand
Diving Signals (cont)
• Other types of signals include:
– Surface-to-diver, recalling diver from the water:
• Hammer-rapping four times on the boat hull or suspended
steel plate
• Bell held underwater and struck four times
• Hydrophone, underwater speaker or sound beacon
• Strobe flashed four times
Diving Signals (cont)
• Line signals may be used for surface-supplied diving
and for scuba in limited visibility
– A list of line pull signals can be found in the NOAA Diving
Manual
• Surface signals may be used to attract attention
– Whistle
– Flare
– Flashing strobe
– Flags
– Hand/arm signals
Air Consumption Rates
• Respiratory Minute Volume (RMV) is the total volume
of air moved in and out of the lungs in one minute
• Actual cubic feet (acf) is the unit of measure that
expresses actual gas volume in accordance with the
General Gas Law. Actual cubic feet per minute (ACFM)
is a consumption rate
• Standard cubic feet (scf) is the unit of measure
expressing surface equivalent volume, under standard
conditions, for any given actual gas volume. Standard
cubic feet per minute (SCFM) is a consumption rate
Calculating Air Consumption Rates
Consumption rate at depth can be estimated by
determining the appropriate RMV for the anticipated
exertion level and the absolute pressure of the dive
depth, using:
Cd = RMV (Pa)
Where
Cd = consumption rate at depth in scfm
RMV = respiratory minute volume in acfm
Pa = absolute pressure (ata) at dive depth
Calculating Air Consumption Rates
Problem: Compute the air consumption rate for a 50 ft (15 m) dive
requiring moderate work, maximum walking speed on a hard
bottom (see table 8.5 in NOAA Diving Manual)
Solution:
Cd = RMV (Pa)
RMV = 1.1 acfm (from Table 8.5)
Pa = 50/33 +1 = 2.51 ata
Cd = (1.1 acfm)(2.51 ata) = 2.76 scfm
Determining Individual Air
Consumption Rates
• Surface Air Consumption Rate (SAC) can be used to
calculate estimated air consumption rate at any depth
– Conduct a dive to a constant depth, and record
beginning and ending pressure gauge readings and
elapsed time
– Subtract ending psi from beginning psi
– Determine SAC from:
SAC = change in psi/time
(depth in ft + 33)/33
SAC Problem
• A diver swims at 30 ft (9 m) for ten minutes. The
submersible pressure gauge reads 2,350 psi at the start
and 2,050 at the end. What is the diver’s SAC?
SAC = 300 psi/10 min = 15.7 psi/min
(30 + 33)/33
• Multiply the SAC by ata to get consumption rate for any
depth
Converting SAC from psi/min to ft3/min
• SAC can be converted to RMV using cylinder
constants (see Table 8.7 NOAA Diving Manual)
• For example, converting the previous example
SAC of 15.7 psi/min, using an aluminum 80
cubic foot cylinder (constant of 0.0266):
RMV = 15.7 psi/min X 0.0266 ft3/psi = 0.42 ft3/min (ACFM)
Scuba Cylinder Duration
• Knowing the estimated duration of the scuba air supply is vital to
proper dive planning
• For a given scuba cylinder, the ratio of rated volume to rated
pressure is a constant (k):
Scuba Cylinder Duration (cont)
• Air supply duration can be estimated using this equation:
Da = Va/Cd
Where
Da = duration in min
Va = available volume in scf
Cd = consumption at depth in scfm
• The available volume depends on the type (rated volume and
pressure) and number of cylinders used, the gauge pressure
measured, and the recommended minimum cylinder pressure
• Consumption rate depends on the depth and exertion level
Scuba Cylinder Duration (cont)
• For planning purposes, the available volume of air is the difference
between the deliverable volume at a given cylinder pressure and the
recommended minimum cylinder pressure (430 psi for steel 72 ft3
and 600 psi for aluminum 80 ft3)
• The available volume can be calculated using:
Va = N(Pg-Pm)k
Where
Va = available volume in scf
N = number of cylinders
Pg = gauge pressure in psig
Pm = recommended minimum pressure in psig
k = cylinder constant
Scuba Cylinder Duration (cont)
•
Estimate the duration of a twin 80 ft3 (2,318 L) aluminum
cylinders filled to 2,4000 psig for a 70 ft (21 m) dive for a diver
with a RMV of 0.6 acfm
Da = Va/Cd
Step 1: Determine Va:
Va = N (Pg-Pm)k
= 2(2,400 psig - 600 psig) (0.0266 scf/psig)
= 95.8 scf
Step 2: Determine Cd:
Cd = RMV (Pa)
= 0.6 acfm (70/33 +1)
= 1.87 acfm
Step 3: Solve for Da:
Da = Va/Cd = 95.8 scf/1.87 scfm = 51.2 min
Surface-Supplied Air
Requirements
• Generally the same as for scuba, except where
free-flow or free-flow/demand systems are used
– Use actual cubic feet per minute instead of RMV
• Demand/Free-flow system has a minimum flow rate of 1.5
acfm
• Free-flow system has a minimum flow rate of 6.0 acfm
Study Questions
• Use the following study questions to
review some of the information presented
in this self study module. When you are
finished you can print out your study
questions results.
Self-study Questions
• Which of these underwater
conditions should be considered in
dive planning?
–a.
–b.
–c.
–d.
Tides
Currents
Visibility
All of the above
Self-study Questions
• Which of these underwater
conditions should be considered in
dive planning?
–a.
–b.
–c.
–d.
Tides
Currents
Visibility
All of the above
Self-study Questions
• According to the NOAA Diving
Manual, most diving is performed at
depths less than how many feet?
–a.
–b.
–c.
–d.
100 feet
110 feet
120 feet
130 feet
Self-study Questions
• According to the NOAA Diving
Manual, most diving is performed at
depths less than how many feet?
–a.
–b.
–c.
–d.
100 feet
110 feet
120 feet
130 feet
Self-study Questions
• Which of these are some of the
divemaster’s responsibilities?
–a.
–b.
–c.
–d.
Maintaining the diving log
Inspection of equipment
Safe execution of all diving
All of the above
Self-study Questions
• Which of these are some of the
divemaster’s responsibilities?
–a.
–b.
–c.
–d.
Maintaining the diving log
Inspection of equipment
Safe execution of all diving
All of the above
Self-study Questions
• The diver is responsible for their own
proper physical condition.
–a.
–b.
True
False
Self-study Questions
• The diver is responsible for their own
proper physical condition.
–a.
–b.
True
False
Self-study Questions
• Divers should avoid or limit diving in
moderate seas.
–a.
–b.
True
False
Self-study Questions
• Divers should avoid or limit diving in
moderate seas.
–a.
–b.
True
False
Self-study Questions
• Is a mud bottom more or less limiting
to divers?
–a.
–b.
More limiting
Less limiting
Self-study Questions
• Is a mud bottom more or less limiting
to divers?
–a.
–b.
More limiting
Less limiting
Self-study Questions
• Hand signals are used to convey
advanced information.
–a.
–b.
True
False
Self-study Questions
• Hand signals are used to convey
advanced information
.
–a.
–b.
True
False
Self-study Questions
• Which of these can be used as
alternative signaling methods?
–a.
–b.
–c.
–d.
–e.
Flares
Flags
Whistles
Hand signals
All of the above
Self-study Questions
• Which of these can be used as
alternative signaling methods?
–a.
–b.
–c.
–d.
–e.
Flares
Flags
Whistles
Hand signals
All of the above
Self-study Questions
• The consumption rate at depth can be
estimated by determining the
appropriate RMV for anticipated
exertion level only.
–a.
–b.
True
False
Self-study Questions
• The consumption rate at depth can be
estimated by determining the
appropriate RMV for anticipated
exertion level only.
–a.
–b.
True
False
Self-study Questions
• Which of these factors influence
scuba air requirements?
–a.
–b.
–c.
–d.
–e.
Depth
Bottom time
Normal ascent time
All of the above
None of the above
Self-study Questions
• Which of these factors influence
scuba air requirements?
–a.
–b.
–c.
–d.
–e.
Depth
Bottom time
Normal ascent time
All of the above
None of the above
Self-study Questions
• Are estimations of air-supply
requirements for surface-supplied
divers the same as scuba divers?
– a.
Yes
– B. No
– c. Yes, except when free-flow systems are used
– D. Yes, except when free-flow systems or freeflow/demand breathing systems are used
Self-study Questions
• Are estimations of air-supply
requirements for surface-supplied
divers the same as scuba divers?
– a.
Yes
– B. No
– c. Yes, except when free-flow systems are used
– D. Yes, except when free-flow systems or freeflow/demand breathing systems are used
Self-study Questions
• Breath-hold diving equipment is
generally used for shallow-water
photography.
–a.
–b.
True
False
Self-study Questions
• Breath-hold diving equipment is
generally used for shallow-water
photography.
–a.
–b.
True
False
Self-study Questions
• Closed-circuit systems are generally
used for observations of short
duration.
–a.
–b.
True
False
Self-study Questions
• Closed-circuit systems are generally
used for observations of short
duration.
–a.
–b.
True
False
Self-study Questions
• Divers should be extremely cautious
around underwater wrecks or other
structures in low visibility to avoid
swimming inadvertently into an
area with overhangs.
a.True
b.False
Self-study Questions
• Divers should be extremely cautious
around underwater wrecks or other
structures in low visibility to avoid
swimming inadvertently into an
area with overhangs.
a.True
b.False
Self-study Questions
• Should divemasters review hand
signals with all divers?
a.Yes
b.No
Self-study Questions
• Should divemasters review hand
signals with all divers?
a.Yes
b.No
Self-study Questions
• Line signals are used as backups to
voice communications only.
a.True
b.False
Self-study Questions
• Line signals are used as backups to
voice communications only.
a.True
b.False
Self-study Questions
• Surface-supplied personnel working
with a diver should be qualified
divers as well.
a. True
b. False
Self-study Questions
• Surface-supplied personnel working
with a diver should be qualified
divers as well.
a. True
b. False
Self-study Questions
• Does physiological research yield
useful estimates of RMV?
a. Yes
b. No
Self-study Questions
• Does physiological research yield
useful estimates of RMV?
a. Yes
b. No