Dive Planning

1. Dive Planning

2. 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.

3. Objectives • Upon completion of this module, the participant will be able to: • 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. Environmental Conditions • Diving operations conducted in harbors, rivers, or shipping channels may pose serious problems • Display the proper signal flag, shape and lights

17. 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

18. 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

19. 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?

20. Diving Signals (cont) Going down Going up Stop OK Something Is wrong OK? OK! Help! Low on air Out of air

21. Diving Signals (cont) Come here Go that way I am cold Me, or Watch me Which Direction? Slow down yes no Ear not clearing Look down Hold hands Get with buddy You lead, I’ll follow What time, What depth? I don’t understand

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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)

30. 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):

31. 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

32. 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

33. 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

34. 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

35. 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.

36. Self-study Questions • Which of these underwater conditions should be considered in dive planning? • a. Tides • b. Currents • c. Visibility • d. All of the above

37. Self-study Questions • Which of these underwater conditions should be considered in dive planning? • a. Tides • b. Currents • c. Visibility • d. All of the above

38. Self-study Questions • According to the NOAA Diving Manual, most diving is performed at depths less than how many feet? • a. 100 feet • b. 110 feet • c. 120 feet • d. 130 feet

39. Self-study Questions • According to the NOAA Diving Manual, most diving is performed at depths less than how many feet? • a. 100 feet • b. 110 feet • c. 120 feet • d. 130 feet

40. Self-study Questions • Which of these are some of the divemaster’s responsibilities? • a. Maintaining the diving log • b. Inspection of equipment • c. Safe execution of all diving • d. All of the above

41. Self-study Questions • Which of these are some of the divemaster’s responsibilities? • a. Maintaining the diving log • b. Inspection of equipment • c. Safe execution of all diving • d. All of the above

42. Self-study Questions • The diver is responsible for their own proper physical condition. • a. True • b. False

43. Self-study Questions • The diver is responsible for their own proper physical condition. • a. True • b. False

44. Self-study Questions • Divers should avoid or limit diving in moderate seas. • a. True • b. False

45. Self-study Questions • Divers should avoid or limit diving in moderate seas. • a. True • b. False

46. Self-study Questions • Is a mud bottom more or less limiting to divers? • a. More limiting • b. Less limiting

47. Self-study Questions • Is a mud bottom more or less limiting to divers? • a. More limiting • b. Less limiting

48. Self-study Questions • Hand signals are used to convey advanced information. • a. True • b. False

49. Self-study Questions • Hand signals are used to convey advanced information. • a. True • b. False

50. Self-study Questions • Which of these can be used as alternative signaling methods? • a. Flares • b. Flags • c. Whistles • d. Hand signals • e. All of the above