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Through careful and thorough planning, the
divers can be properly prepared for the underwater conditions at the diving site.
The diver will employ the following techniques to adapt to underwater conditions:
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Upon reaching the bottom and before leaving the area of the stage or descent
line, the diver adjusts buoyancy and makes certain that the air supply is
adequate.
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The diver becomes oriented to the bottom and the work site using such clues
as the lead of the umbilical, natural features on the bottom, the direction of
current. However, bottom current may differ from the surface current. The
direction of current flow may change significantly during the period of the
dive. If the diver has any trouble in orientation, the tender can guide the diver
by using the line-pull searching signals.
The diver is now ready to move to the work site and begin the assignment.
The best safety factors are a positive, confident attitude about
diving and careful advance planning for emergencies. A diver in trouble underwater
should relax, avoid panic, communicate the problem to the surface and
carefully think through the possible solutions to the situation. Topside support
personnel should implement emergency job-site procedures as indicated in
Chapter 6. In all situations, the Diving Supervisor should ensure that common
sense and good seamanship prevail to safely resolve each emergency.
Emergency procedures are covered specifically for each equipment in its appropriate
operations and maintenance manual and in general in Chapter 6. However,
there are a number of situations a diver is likely to encounter in the normal range
of activity which, if not promptly solved, can lead to full-scale emergencies. These
situations and the appropriate action to be taken follow.
As soon as a diver discovers that the umbilical has
become fouled, the diver must stop and examine the situation. Pulling or tugging
without a plan may only serve to complicate the problem and could lead to a
severed hose. The Diving Supervisor is notified if possible (the fouling may
prevent transmission of line-pull signals). If the lines are fouled on an obstruction,
retracing steps should free them. If the lines cannot be cleared quickly and easily,
the standby diver is sent down to assist. The standby diver is sent down as normal
procedure, should communications be interrupted and the tender be unable to haul
the diver up. The standby diver, using the first diver’s umbilical (as a descent line),
should be able to trace and release the lines. If it is impossible to free the first
diver, the standby diver should signal for a replacement umbilical.
If the diver becomes fouled with the descent line and
cannot be easily cleared, it is necessary to haul the diver and the line to the surface,
or to cut the weight free of the line and attempt to pull it free from topside. If the
descent line is secured to an object or if the weight is too heavy, the diver may
have to cut the line before being hauled up. For this reason, a diver should not
descend on a line that cannot be cut.
WARNING | : | TIf job conditions call for using a steel cable or a chain as a descent line,
the Diving Officer must approve such use. |
When working at mid-depth in the water column, the diver should keep a
hand on the stage or rigging to avoid falling. The diver avoids putting an arm overhead
in a dry suit; air leakage around the edges of the cuffs may change the suit
buoyancy and increase the possibility of a fall in the water column.
If a leak occurs in the helmet, the diver’s
head is lowered and the air pressure slightly increased to prevent water leakage. A
leak in the diving suit only requires remaining in an upright position; water in the
suit does not directly endanger breathing.
1. Before the dive, the tender carefully checks the diving dress with particular
attention to the nonreturn valve, air control valve, helmet locking device,
intercom system, helmet seal and harness.
2. When the diver is ready, the tenders dress and assist the diver to the stage or
ladder or waters edge, always keeping a hand on the umbilical.
3. The primary tender and a backup tender as required are always on station to
assist the diver. As the diver enters the water, the tenders handle the umbilical,
using care to avoid sharp edges. The umbilical must never be allowed to run
free or be belayed around a cleat or set of bitts. Pay out of the umbilical is at a
steady rate to permit the diver to descend smoothly. If a stage is being used,
the descent rate is coordinated with the winch operator or line handlers.
4. Throughout the dive the tender keeps slack out of the line while not holding it
too tautly. Two or three feet of slack permits the diver freedom of movement
and prevents the diver from being pulled off the bottom by surging of the
support craft or the force of current acting on the line. The tender occasionally
checks the umbilical to ensure that movement by the diver has not resulted in
excessive slack. Excessive slack makes signaling difficult, hinders the tender
from catching the diver if falling and increases the possibility of fouling the
umbilical.
5. The tender monitors the umbilical by feel and the descent line by sight for any
line-pull signals from the diver. If an intercom is not being used, or if the diver
is silent, the tender periodically verifies the diver’s condition by line-pull
signal. If the diver does not answer, the signal is repeated; if still not answered,
the Diving Supervisor is notified. If communications are lost, the situation is
treated as an emergency (see paragraph 6-12.5.3.2 for loss-of-communication
procedures).
The Diving Supervisor and designated members
of the dive team constantly monitor the diver’s progress and keep track of his
relative position.
Supervisor Actions.
1. Follow the bubble trail, while considering current(s). If the diver is
searching the bottom, bubbles move in a regular pattern. If the diver is
working in place, bubbles do not shift position. If the diver has fallen, the
bubbles may move rapidly off in a straight line.
2. Monitor the pneumofathometer pressure gauge to keep track of operating
depth. If the diver remains at a constant depth or rises, the gauge provides
a direct reading, without the need to add air. If the diver descends, the hose
must be cleared and a new reading made.
Tender Actions. Feel the pull of the umbilical.
Additional Personnel Actions. Monitor the gauges on the supply systems for
any powered equipment. For example, the ammeter on an electric welding unit
indicates a power drain when the arc is in use; the gas pressure gauges for a
gas torch registers the flow of fuel. Additionally, the pop made by a gas torch
being lighted will probably be audible over the intercom and bubbles from the
torch will break on the surface, giving off small quantities of smo
Divers should follow these guidelines for movement
on the bottom areas:
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Before leaving the descent line or stage, ensure that the umbilical is not fouled.
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Loop one turn of the lifeline and air hose over an arm; this acts as a buffer
against a sudden surge or pull on the lines.
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Proceed slowly and cautiously to increase safety and to conserve energy.
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If obstructions are encountered, adjust buoyancy to pass over the obstruction
(not under or around). If you pass around an obstruction, you must return by
the same side to avoid fouling lines.
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When using buoyancy adjustments to aid in movement, avoid bouncing along
the bottom; all diver movements are controlled.
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If the current is strong, stoop or crawl to reduce body area exposed to the current.
Adjust the inflation of the dress to compensate for any change in depth,
even if the change is only a few feet.
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When moving on a rocky or coral bottom, make sure lines do not become
fouled on outcroppings, guarding against tripping and getting feet caught in
crevices. Watch for sharp projections that can cut hoses, diving dress or unprotected
hands. The tender is particularly careful to take up any slack in the
diver’s umbilical to avoid fouling.
Guard against slipping and falling on gravel bottoms, especially on slopes.
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Avoid unnecessary movements that stir up the bottom and impair visibility.
CAUTION | : | Avoid overinflation and be aware of the possibility of blowup when
breaking loose from mud. It is better to call for aid from the standby
diver than to risk blowup. |
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Mud and silt may not be solid enough to support your weight. Many hours
may be spent working under mud without unreasonable risk. The primary hazard
with mud bottoms comes from the concealment of obstacles and
dangerous debris.
If appropriate electronic searching equipment is not
available, it may be necessary to use unaided divers to conduct the search. Procedures
for searching on the bottom with unaided divers are:
1. A diver search of the bottom can be accomplished with a circling line, using
the descent line as the base point of the search. The first sweep is made with
the circling line held taut at a point determined by the range of visibility. If
possible, the descent line should be in sight or, if visibility is limited, within
reach. The starting point is established by a marker, a line orientation with the
current or the light, signals from topside, or a wrist compass. After a full 360-
degree sweep has been made, the diver moves out along the circling line
another increment (roughly double the first) and makes a second sweep in the
opposite direction to avoid twisting or fouling the lifeline and air hose.
2. If the object is not found when the end of the circling line has been reached,
the base point (the descent line) is shifted. Each base point in succession
should be marked by a buoy to avoid unnecessary duplication in the search. If
the search becomes widespread, many of the marker buoys can be removed,
leaving only those marking the outer limits of the area.
3. If the diver is unable to make a full circle around the descent line because of
excessive current or obstructions, the search patterns are adjusted accordingly.
4. A linear search pattern (Jack-Stay) can be established by laying two large
buoys and setting a line between them. A diving launch, with a diver on the
bottom, can follow along the line from buoy to buoy, coordinating progress
with the diver who is searching to each side of the established base line. These
buoys may be readjusted to enlarge search areas.
5. Once the object of a search is located, it is marked. The diver can secure the
circling line to the object as an interim measure, while waiting for a float line
to be sent down.
Divers are often required to work in enclosed or
confined spaces. Enclosed space diving shall be supported by a surface-supplied
air system (MK 20 MOD 0 and MK 21 MOD 1).
The interior of sunken ships, barges, submarine ballast
tanks, mud tanks, sonar domes, and cofferdams is hazardous due to limited access,
poor visibility, and slippery surfaces. Enclosed spaces may be dry or flooded, and
dry spaces may contain a contaminated atmosphere.
NOTE. | | When a diver is working in an enclosed or confined space, the Diving
Supervisor shall have the diver tended by another diver at the access
opening. Ultimately, the number of tending divers deployed depends on
the situation and the good judgement of the Diving Officer, Master Diver,
or Diving Supervisor on the site. |
Because of the hazards involved in enclosed
space operations, divers must rigorously adhere to the following warnings.
WARNING | : | During enclosed space diving, all divers shall be outfitted with MK 21
MOD 1 with EGS or MK 20 MOD 0 that includes a diver-to-diver and diverto-
topside communications system and an EGS for the diver inside the
space. |
WARNING | : | The divers shall not remove their diving equipment until the atmosphere
has been flushed twice with air from a compressed air source meeting
the requirements of Chapter 4, or the submarine L.P. blower, and tests
confirm that the atmosphere is safe for breathing. Tests of the air in the enclosed space shall be conducted hourly. Testing shall be done in
accordance with NSTM 074, Volume 3, Gas Free Engineering (S9086-CHSTM-
030/CH-074) for forces afloat, and NAVSEA S-6470-AA-SAF-010 for
shore-based facilities. If the divers smell any unusual odors they shall
immediately don their masks. |
WARNING | : | If the diving equipment should fail, the diver shall immediately switch to
the EGS and abort the dive. |
When working around corners where the umbilical is
likely to become fouled or line-pull signals may be dissipated, a second diver
(tending diver) may be sent down to tend the lines of the first diver at the obstruction
and to pass along any line-pull signals. Line-pull signals are used when audio
communications are lost, and are passed on the first diver’s lines; the tending diver
uses his own lines only for signals directly pertaining to his own situation.
When working inside a wreck, the same procedure of
deploying tending divers is followed. This technique applies to the tending divers
as well: every diver who penetrates a deck level has another tending diver at that
level, or levels, above. Ultimately, the number of tending divers deployed depends
on the situation and the good judgment of the Diving Officer, Master Diver, or
Diving Supervisor on the site. Obviously, an operation requiring penetration
through multiple deck levels requires detailed advanced planning in order to
provide for the proper support of the number of divers required. MK 21 MOD 1
and MK 20 MOD 0 are the only equipment approved for working inside a wreck.
The diver enters a wreck feet first and never uses force to gain entry through an
opening.
When working with or near lines or
moorings, observe the following rules:
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Stay away from lines under strain.
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Avoid passing under lines or moorings if at all possible; avoid brushing
against lines or moorings that have become encrusted with barnacles.
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If a line or mooring is to be shifted, the diver is brought to the surface and, if
not removed from the water, moved to a position well clear of any hazard.
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If a diver must work with several lines (messengers, float lines, lifting lines,
etc.) each should be distinct in character (size or material) or marking (color
codes, tags, wrapping).
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Never cut a line unless the line is positively identified.
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When preparing to lift heavy weights from the bottom, the lines selected must
be strong enough and the surface platform must be positioned directly over the
object to be raised. Prior to the lift, make sure the diver is clear of the lift area
or leaves the water.
Bottom checks are conducted after returning to the stage or
descent line and prior to ascent. The checks are basically the same for each rig.
1. Ensure all tools are ready for ascent.
2. Check that all umbilicals and lines are clear for ascent.
3. Assess and report your condition (level of fatigue, remaining strength,
physical aches or pains, etc.) and mental acuity.
The range of diving jobs is wide and varied. Many jobs
follow detailed work procedures and require specific predive training to ensure
familiarity with the work. The U.S. Navy Underwater Work Techniques Manual,
Volumes 1 and 2, NAVSEA 0994-LP-007-8010 and NAVSEA 0994-LP-007-
8020, presents guidance for most commonly encountered jobs, such as clearing
fouled propellers, patching collision damage, replacing underwater valves or
fittings, preparing for salvage of sunken vessels, and recovering heavy objects
from the bottom.
With the advent of more highly technical
underwater work procedures, the Underwater Ship Husbandry Manual,
S0600-AA-PRO-010, was published. Like the Naval Ships Technical Manual
(NSTM), the manual is published in separately bound chapters, each dealing with
a separate area of underwater work. Chapter 1 of the manual (S0600-AA-PRO-
010) is the Index and User Guide, which provides information on the subsequent
chapters of the manual.
Underwater work requires appropriate tools and materials,
such as cement, foam plastic, and patching compounds. Many of these are standard
hand tools (preferably corrosion-resistant) and materials; others are specially
designed for underwater work. A qualified diver will become familiar with the
particular considerations involved in working with these various tools and materials
in an underwater environment. Hands-on training experience is the only way
to get the necessary skills. Consult the appropriate operations and maintenance
manuals for the use techniques of specific underwater tools. In working with tools
the following basic rules always apply:
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Never use a tool that is not in good repair. If a cutting tool becomes dulled,
return it to the surface for sharpening.
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Do not overburden the worksite with unnecessary tools, but have all tools that
may be needed readily available.
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Tools are secured to the diving stage by lanyard, carried in a tool bag looped
over the diver’s arm, or lowered on the descent line using a riding shackle and
a light line for lowering. Prior to ascent or descent, secure power to all tools.
Attach lanyards to all tools, connectors, shackles and shackle pins.
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Using the diving stage as a worksite permits organization of tools while providing
for security against loss. The stage also gives the diver leverage and
stability when applying force (as to a wrench), or when working with a power
tool that transmits a force back through the diver.
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Tying a hogging line to the work also gives the diver leverage while keeping
him close to his task without continually having to fight a current.
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