18-5 OPERATIONS PLANNING

OPERATIONS PLANNING

Certain factors must be taken into consideration in the planning of the oxygen dive operation. The following gives detailed information on specific areas of planning.

Operating Limitations

Diving Officers and Diving Supervisors must consider the following potential limiting factors when planning closed-circuit oxygen combat swimmer operations:

• UBA oxygen supply (paragraph 18-3.2)
• UBA canister duration (NAVSEA 10560 ltr ser 00C35/3215, 22 Apr 96)
• Oxygen exposure limits (paragraphs 18-4.7 and 18-4.8)
• Thermal factors (Chapter 11 and Chapter 19)

Maximizing Operational Range

The operational range of the UBA may be maximized by adhering to these guidelines:

• Whenever possible, plan the operation using the turtleback technique, in which the diver swims on the surface part of the time, breathing air where feasible.
• Use tides and currents to maximum advantage. Avoid swimming against a current when possible.
• Ensure that oxygen bottles are charged to a full 3,000 psig (200 bar) before the dive.
• Minimize gas loss from the UBA by avoiding leaks and unnecessary depth changes.
• Maintain a comfortable, relaxed swim pace during the operation. For most divers, this is a swim speed of approximately 0.8 knot. At high exercise rates, the faster swim speed is offset by a disproportionately higher oxygen consumption, resulting in a net decrease in operating range. High exercise rates may reduce the oxygen supply duration below the canister carbon dioxide scrubbing duration and become the limiting factor for the operation (paragraph 18-3.2)
• Ensure divers wear adequate thermal protection. A cold diver will begin shivering or increase his exercise rate, either of which will increase oxygen consumption and decrease the operating duration of the oxygen supply.

WARNING   The MK 25 does not have a carbon dioxide-monitoring capability. Failure to adhere to canister duration operations planning could lead to unconsciousness and/or death.

Training

Training and requalification dives shall be performed with the following considerations in mind:

• Training dives shall be conducted with equipment that reflects what the diver will be required to use on operations. This should include limpets, demolitions, and weapons as deemed appropriate.
• Periodic classroom refresher training shall be conducted in oxygen diving procedures, CNS oxygen toxicity and management of diving accidents.
• Develop a simple set of hand signals, including the following signals:

— Surface				— Okay
— Emergency Surface				— Feel Strange
— Descend				— Ear Squeeze
— Ascend				— Stop
— Speed Up				— Caution
— Slow Down				— Excursion

• Match swim pairs according to swim speed.
• If long duration oxygen swims are to be performed, work-up dives of gradually increasing length are recommended.

Personnel Requirements

The following topside personnel must be present on all training and exercise closed-circuit oxygen dives:

• Diving Supervisor/Boat Coxswain
• Standby diver/surface swimmer with air (not oxygen) scuba
• Diving Medical Technician/Special Operations Technician (standby diver tender)

Equipment Requirements

The operational characteristics of the MK 25 UBA are shown in Table 18-7. Equipment requirements for training and exercise closedcircuit oxygen dives are shown in Table 18-8. Several equipment items merit special consideration as noted below:

• Motorized Chase Boat. A minimum of one motorized chase boat must be present for the dive. Safe diving practice in many situations, however, would require the presence of more than one chase boat (e.g., night operations). The Diving Supervisor must determine the number of boats required based on the diving area, medical evacuation plan and number of personnel participating in the dive. When more than one safety craft is used, communications between support craft should be available.
• Buddy Lines. Because the risk is greater that a diver will become unconscious or disabled during a closed-circuit oxygen dive than during other types of dives, buddy lines are required equipment for oxygen dives. In a few special diving scenarios, when their use may hinder or endanger the divers, buddy lines may not be feasible. The Diving Supervisor must carefully consider each situation and allow buddy lines to be disconnected only when their use will impede the performance of the mission.
• Depth Gauge. The importance of maintaining accurate depth control on oxygen swims mandates that a depth gauge be worn by each diver.

table 18-7 Equipment Operational Characteristics.

table 18-8 Closed-Circuit Oxygen Diving Equipment.

Transport and Storage of Prepared UBA

Once the UBA has been set up, the mouthpiece valve must be placed in the SURFACE position and the oxygensupply valve turned off. In this configuration, the rig is airtight and the carbon dioxide absorbent in the canister is protected from moisture which can impair carbon dioxide absorption. Two weeks is the maximum allowable time a rig may be stored from preparation to the time the rig is used.

High temperatures during transport and storage will not adversely affect approved CO2 absorbent; however, storage temperatures below freezing may decrease performance and should be avoided. Should additional carbon dioxide absorbents other than those provided in Table 18-3 be approved for use in closed-circuit UBAs, the manufacturer’s recommendations regarding storage temperatures shall be followed.

In the event an operation calls for an oxygen dive followed by a surface interval and a second oxygen dive, the UBA shall be sealed during the surface interval as described above. It is not necessary to change carbon dioxide absorbent in the UBA before the second dive as long as the combined oxygen time of both dives does not exceed the canister duration limits.

Predive Precautions

The following items shall be determined prior to the diving operation:

• Means of communicating with the nearest available Diving Medical Officer.
• Location of the nearest functional recompression chamber. Positive confirmation of the chamber’s availability must be obtained prior to diving.
• Nearest medical facility for treatment of injuries or medical problems not requiring recompression therapy.
• Optimal method of transportation to recompression chamber or medical facility. If coordination with other units for aircraft/boat/vehicle support is necessary, the Diving Supervisor must know the frequencies, call signs and contact personnel needed to make transportation available in case of emergency. A medical evacuation plan must be included in the Diving Supervisor brief.
• The preparation of a checklist similar to that found in Chapter 6 is recommended.
• When operations are to be conducted in the vicinity of ships, the guidelines provided in the Ship Repair Safety Checklist (Chapter 6) and appropriate Naval Special Warfare Group instructions shall be followed.
• Notification of intent to conduct diving operations must be sent to the appropriate authority in accordance with local directives.