Surface Supplied Air Tender’s Course & U.S. Navy Tables

1. Surface Supplied Air Tender’s Course & U.S. Navy Tables Presented By: The Riverside County Sheriff’s Underwater Search and Recovery Team

2. Surface Supplied Air (SSA) Diving-Tender • Responsibilities: • Help Divers Suiting Up • Maintaining SSA Equipment • Gas Management • Field Neuro Exams • Communications • Timekeeping and Tables • Assisting with Rescues • Have more responsibilities than divers because they are responsible for divers.

3. Predive Environmental Checklist • Know the dive depths • Dive Altitude • Water temperature • Underwater visibility • Bottom type • Hazards

4. Personnel to Run SSA Dive Operations • Diver • Tender • Dive Supervisor* • Standby Diver • Standby Tender • Timekeeper/Board Operator • Boat Operator*

5. Tender-Prior to Water • Checks the diver’s Equipment • Drysuit • Harness • Bailout system • Manifold block • Weighting • Air check • AGA • Communication

6. Tender-Prior to Water • Checks air supply (bank) • Nueros • Maintains contact with the diver once he is dressed • Helps diver to entry point

7. Tender-In the Water • Communication Check • Takes care of diver’s umbilical • Communications • Assists board operator with times and depth information • Can rotate between jobs, but only after his/her diver is out of the water

8. Emergencies • Fouling • Blow up • Loss of primary air supply • Loss of communications or contact

9. Postdive Procedures • Help diver out of equipment • Stow umbilicals • Field Neuros • Post dive maintenanceon equipment

10. Timekeeper/Board operator • Keeps accurate records of dive times • Depths • Notes all important details of dive • Monitors rates of flow • Cannot change job until ALL divers are out of water.

11. Supply Pressure Requirements-Demand System • Helps eliminate low levels of CO2 • Basic Formula for determining require air pressures: • (depth in fsw X .445) + Manufacturer’s recommendation over ambient pressure setting= minimum supply pressure. • Example: [(130 fsw X .445) + 135 psig] (57 psi + 135 psig) = 192. 2 psig This is the amount needed for the diver to breathe easily at depth.

12. U.S. Navy Tables • What Are Dive Tables? • They are a are printed cards or booklets that allow divers to determine for a particular dive profile and breathing gas, the decompression stops required for that dive in order to avoid decompression sickness. • In actuality, they are a “theoretical” model or limit of a decompression procedure that does not establish a hard line between developing or not developing decompression sickness. • Basically, using these tables establishes an “acceptable risk” and you can still get bent using them.

13. Dive Planning • Single Vs. Repetitive Dive • Single dive: A dive made within more than 12 hours following a previous dive. • Repetitive dive: A dive made less than 12 hours after surfacing from a prior dive. • Planning a single dive-Definitions: • Know Actual Bottom time (ABT) • Know No Decompression Limits (NDL) • Know Depth • Know Dive Schedule

14. Dive Planning • ABT starts when the diver leaves the surface and ends when the diver begins a direct, uninterrupted ascent to the surface. • No Decompression limit is the maximum time a diver can stay at a given depth. • Depth is defined as the maximum depth reached during any point of the dive—even if the diver is there momentarily. • “Dive Schedule” refers to the combination of ABT and Depth as they appear on the table.

15. Dive Planning Start of Descent Actual Bottom Time Start of Ascent Maximum Depth Dive Profile

16. NDL • No Decompression Limits • Left side of the table • What is the NDL for 60 feet? • What is the NDL for 100 feet • What is the NDL for 140

17. Question? • Can a team make a dive to 80 feet for 45 minutes? • No. The NDL is 39 minutes

18. Repetitive Dives • More complex than single dive planning. • Need to remember two things: • A simple written means of recording all information pertaining to the dives that were made. • Need dive table information that accounts for the residual nitrogen (RNT) present from previous dives

19. Recording Repetitive Dives End of ascent/start of surface interval Start of descent/end of surface interval Start of Descent Surface Interval Time (SIT) Schedule Used / Repetitive letter group Depth RNT +ABT ESDT Time ABT Start of Ascent

20. Accounting For Residual Nitrogen • Table 9-7 Repetitive Group Designation • Table 9-8 Combination of two tables. • Upper table depicts how the surface interval reduces excess nitrogen • Lower table shows how divers must account for this excess nitrogen on subsequent dives.

21. Dive Planning • After a single dive of 47 feet with an actual bottom time of 39 minutes answer the following questions: • What is the Schedule used? • 50’ / :41 • What is the repetitive group designation at the end of the dive? • F

22. Repetitive Group After Surface Interval • The longer the diver remains on the surface after a dive, the less residual nitrogen (RNT) will be present in the diver’s tissues. • The surface interval must be accounted for and a “new” Repetitive Group Designator must be assigned • This “new” designator affects how long a diver can remain underwater on repetitive dives, without exceeding the NDLs.

23. Repetitive Group After Surface Interval • Determine the surface interval time (SIT). • The surface interval is the time from the diver surfaces, spends sitting on the surface, and to their next descent. • After the SIT, find the “new” Group Designator • This is found on table 9-8. Start with the last designator, find the time from surface to descent (or planned descent) and follow down to new designator.

24. Dive Planning • Starting with the last dive, our ending Repetitive Group Designator was F. What is the “new” designator after a 4:04 SIT? • B

25. Determining Adjusted NDL • Accounting for Nitrogen in the diver’s tissues from previous dives. • The RNT must be added into all subsequent repetitive dives. • To determine the Adjusted NDL, subtract the RNT from the NDL of the next dive able depth. • The RNT + ABT = Equivalent Single Dive Time (ESDT) • The ESDT is the factor used to determine dive schedules for all subsequent repetitive dives.

26. Dive Planning • Continuing with the previous dive, find the following with a dive to 46’ for :22: • What is the RNT • What is the Adjusted NDL • What is the ESDT • What is the dive schedule • What is the “new” repetitive group designator?

27. Dive Planning • What is the RNT • 17 • What is the Adjusted NDL • 75 • What is the ESDT • 39 • What is the dive schedule • 50/41 • What is the “new” repetitive group? • F

28. Sample Problems

29. Determining the minimum surface interval • Must know the ESDT for the second dive. The ESDT will be the same as the NDL for the second dives max depth • Deduct the team’s max planned ABT from the max ESDT. This will reveal the RNT. • Consult the bottom of table 9-8 for your depth. Go across that depth until you find your RNT or that close to it. • Follow it up until you find the Repetitive Group. From the first dive’s Group Designation to where the Repetitive Group intersects is the minimum surface interval

30. Sample Problems

31. Dealing with Altitude • Any dive over 1000 feet in altitude is considered an altitude dive. • All altitude dives need special tables • Traveling after an altitude dive • Changes in gauges.

32. Ready for the Test? Need: Scratch paper Calculator Pencil