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OPERATIONAL PLANNING
Because the MK 16 UBA maintains a constant partial pressure of oxygen and only
adds oxygen or diluent gas as needed, dives of long duration are possible. Mission
capabilities, dive procedures, and decompression procedures are radically
different from any other methods. This requires a high level of diver training and
awareness and necessitates careful dive planning. Chapter 6 provides general
guidelines for operational planning. The information provided in this section is
supplemental to the MK 16 UBA O&M manual and provides specific guidelines
for MK 16 UBA dive planning. In addition to any other requirements, at least half
of all dive training should be at night or in conditions of restricted visibility.
Units requiring a deep operational capability should allow frequent opportunity for
training, ensuring diver familiarity with equipment and procedures. Workup
dives are strongly recommended prior to diving at depths greater than 130
fsw. MK 16 diver qualifications may be obtained only by completion of the MK
16 Basic Course (A-431-0075) or the Naval Special Warfare Center MK 16 qualifications
course. MK 16 qualifications remain in effect as long as diver
qualifications are maintained in accordance with Military Personnel Manual
article 1410380. However, a diver who has not made a MK 16 dive in the previous
six months must refamiliarize himself with MK 16 EPs and OPs and must
complete a MK 16 training dive prior to making a MK 16 operational dive. Prior
to conducting MK 16 decompression diving, a diver who has not conducted a
MK 16 decompression dive within the previous six months must complete open
water decompression training dives. Refer to Table 17-1 for the personnel requirements
for MK 16 diving operations.
Operating Limitations. Using combat swimmer multilevel dive (CSMD) procedures
provides SPECWAR divers with the option of conducting multiple-depth
diving with the MK 16 UBA if a maximum depth of 70 fsw (NEDU Report 13-83)
is not exceeded at any time during the dive. Refer to Table 17-2 for equipment
depth limitations. Diving Supervisors must also consider the limiting factors
presented in the following paragraphs when planning closed-circuit UBA
operations.
Oxygen Flask Endurance.In calculating the endurance of the MK 16, only the
oxygen flask is considered. The endurance of the oxygen flask is dependent upon
the following:
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Initial predive pressure.
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Required reserve pressure.
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Oxygen consumption by the diver.
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Effect of cold water immersion on flask pressure.
Flask Floodable Volume. The
oxygen flask floodable volume (fv) is 0.1 cubic foot (2.9
liters).
Initial Predive Pressure. The initial pressure is the pressure of the oxygen flask at
ambient temperature when it has cooled following charging. A reserve pressure of
500 psig is required to drive the reducer. Calculation of initial pressure must also
account for gas loss resulting from UBA predive calibration. Oxygen consumption
by the diver is computed as 0.049 scfm (1.4 lpm). This is a conservative value for
a diver swimming at 0.85 knot (Chapter 3, Figure 3-6). Refer to Table 17-3 for
information on the average breathing gas consumption rates and CO2 absorbent
usage.
Effect of Cold Water Immersion on Flask Pressure.
Immersion in cold water will reduce the flask pressure and
actual cubic feet (acf) of gas available for the diver, in
accordance with Charles’/Gay-Lussac’s gas law. Based upon direct
measurement, available data, or experience, the coldest
temperature expected during the dive is used.
Calculating Gas Endurance. Combining these factors
produces the formula for MK 16 gas endurance:
Example. The endurance of a MK 16
MOD 0 UBA charged to 2,500 psig for a dive in 50° F water when
the ambient air temperature is 65° F would be computed as
follows:
 This duration assumes no gas loss from the UBA during the dive and only
considers metabolic consumption of oxygen by the diver. Divers must be trained
to minimize gas loss by avoiding leaks and unnecessary depth changes. Clearing a
flooded face mask is a common cause of gas loss from the UBA. When a full face
mask (FFM) is used, gas can pass from the UBA breathing loop into the FFM and
escape into the surrounding seawater due to a poor face seal. Leaks that continue
unchecked can deplete UBA gas supply rapidly. Additionally, during diver ascent,
the dump valve opens to discharge breathing gas into the surrounding water,
thereby preventing overinflation of the breathing diaphragm. Depth changes
should be avoided as much as possible to minimize this gas loss.
Diluent Flask Endurance. Under normal conditions the anticipated duration of
the MK 16 diluent flask will exceed that of the oxygen flask. The MK 16 diluent
bottle holds approximately 21 standard cubic feet (595 liters) of gas at a stored
pressure of 3,000 psig. Diluent gas is used to maintain the required gas volume in
the breathing loop and is not depleted by metabolic consumption. As the diver
descends, diluent is added to maintain the total pressure within the recirculation
system at ambient water pressure. Loss of UBA gas due to offgassing at depth
requires the addition of diluent gas to the breathing loop either automatically
through the diluent add valve or manually through the diluent bypass valve to
make up lost volume. Excessive gas loss caused by face mask leaks, frequent
depth changes, or improper UBA assembly will deplete the diluent gas supply
rapidly. Canister Duration. Canister duration is estimated by using a working diver
scenario. This allows an adequate safety margin for the diver in any situation.
Table 17-4 shows the canister duration limits and approved absorbents for the MK
16 UBA. 
Thermal Protection. Divers must be equipped with adequate thermal protection
to perform effectively and safely. A cold diver will either begin to shiver or
increase his exercise rate, both of which will increase oxygen consumption and
decrease oxygen supply duration and canister duration. Refer to Chapter 11 for
guidance on thermal protection.
Equipment Requirements. Equipment requirements for closed-circuit mixed-gas
UBA training dives are provided in Table 17-5. Two equipment items merit
special comment:
Safety Boat. A minimum of one motorized safety boat must be present for all
open-water dives. A safety boat is also recommended for tended pier dives or
diving from shore. Safe diving practice in many situations, however, will
require the presence of more than one safety boat. The Diving Supervisor must
determine the number of boats required based on the diving area, medical
evacuation plan, night operations, and the number of personnel participating in
the dive operation. Buddy Lines. Buddy lines are considered important safety equipment for
closed-circuit UBA dives. In special diving situations, such as certain combat
swimmer operations or tended diving, the use of buddy lines may not be feasible.
The Diving Supervisor shall conduct dives without buddy lines only in
situations where their use is not feasible or where their use will pose a greater
hazard to the divers than by diving without them.
 Distance Line.
Any buddy line over 10 feet (3 meters) in length is referred to as a
distance line. The length of the distance line shall not exceed 81 feet (25 meters).
Distance lines shall be securely attached to both divers. Standby Diver. When appropriate during training and non-influence diving operations,
open circuit scuba may be used to a maximum depth of 130 fsw.
Lines. Diver marker lines shall be manufactured from any light line that is
buoyant and easily marked as directed in paragraph 17-4.2.4 (one-quarter inch
polypropylene is quite suitable). Marking of Lines. Lines used for controlling the depth of the diver(s) for decompression
diving shall be marked. This includes tending lines, marker lines, and lazy-shot lines. Lines shall be marked with red and yellow or black bands starting
at the diver(s) or clump end. Red bands will indicate 50 feet and yellow or black
bands will mark every 10 feet. Diver Marker Buoy. Diver marker buoys will be constructed to provide adequate
visual reference to monitor the divers location. Additionally, the amount of line
will be of sufficient length for the planned dive profile. Depth Gauge/Wrist Watch.
A single depth gauge and wrist watch may be used
when diving with a partner and using a distance line.
Recompression Chamber Considerations. A recompression chamber and a
Diving Medical Officer are not required on station (on station is defined as at the
dive location) as prerequisites for closed-circuit UBA diving operations, unless the
dive(s) will exceed the normal working limit. However, the following items
should be determined prior to beginning diving operations:
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Location of the nearest functional recompression chamber. Positive confirmation
of the chamber’s availability in case of emergency should be obtained.
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Location of the nearest available Diving Medical Officer if not at the nearest
recompression chamber.
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Location of the nearest medical facility for treatment of injuries and medical
problems not requiring recompression therapy.
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The optimal method of transportation to the treatment chamber or medical
facility. If coordination with other units for aircraft/boat/vehicle support is
necessary, the Diving Supervisor shall know the telephone numbers and points
of contact necessary to make these facilities available as quickly as possible in
case of emergency. A medical evacuation plan should be included in the Diving
Supervisor brief. Preparing an emergency assistance checklist similar to
that in Chapter 6 is recommended.
Diving Procedures for MK 16..
Employing a Single, Untended EOD Diver. Generally, it is safer for divers to
work in pairs rather than singly. However, to do so when diving on underwater
influence ordnance doubles the diver bottom time expended, increases the risk to
life from live ordnance detonation, and increases the risk of detonation caused by
the additional influence signature of the second diver. The EOD Diving Officer
may authorize the employment of a single, untended diver when it is deemed that
the ordnance hazard is greater than the hazard presented by diving alone. All
single, untended divers must use a full face mask (FFM). The EOD Diving Officer
or Diving Supervisor shall consider the following factors when deciding whether
to operate singly or in pairs:
Simulated Training Scenarios. Simulated ordnance training scenarios do not
constitute a real threat, therefore single untended divers shall not be used in
training operations. The diver shall be surface tended or marked by attaching a
buoy to him.
EOD Standard Safety Procedures. The following standard safety procedures
shall be observed during EOD diving operations:
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An EOD Diving Officer shall be on scene during all phases of an explosive
ordnance disposal diving operation involving a Render Safe Procedure (RSP).
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When diving on unknown or influence ordnance, the standby diver’s equipment
shall be the same type as the diver neutralizing the ordnance.
Diving Methods. Diving methods include:
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Single Marked Diving. Consists of a single diver with FFM marked with a
lightweight buoyant line attached to a surface float. Upon completion of a dive
requiring decompression, the diver will signal the diving supervisor that he is
ready to surface. The diving boat will then approach the surface float and
recover the diver.
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Paired Marked Diving. Procedures for paired marked diving are identical to
the procedures for a single marked diver, but with the addition of the second
diver connected by a buddy/distance line.
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Tended Diving. Tended diving
consists of a single surface tended
diver or a pair of divers
using a buddy/distance line, with
one diver wearing a depth marked
line that is continuously
tended at the surface (Figure
17-5). A dive pair working off a
master reference buoy is closely
and continuously monitored at the
surface. Divers shall each be positively
attached to the system or
one diver positively attached to
the system and the other positively
attached to the first.
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Ship Safety. When operations are to
be conducted in the vicinity of ships,
the guidelines provided in the Ship
Repair Safety Checklist (see Chapter
6) must be followed.
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Operational Area Clearance. Notification
of intent to conduct diving operations
should be coordinated in accordance
with local directives.
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