surface supplied air tender’s course & u.s. navy tables
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DESCRIPTIONSurface Supplied Air Tender’s Course & U.S. Navy Tables. Presented By: The Riverside County Sheriff’s Underwater Search and Recovery Team. Surface Supplied Air (SSA) Diving-Tender. Responsibilities: Help Divers Suiting Up Maintaining SSA Equipment Gas Management Field Neuro Exams - PowerPoint PPT Presentation
Surface Supplied Air Tenders Course & U.S. Navy TablesPresented By:The Riverside County Sheriffs Underwater Search and Recovery Team
Surface Supplied Air (SSA) Diving-TenderResponsibilities:Help Divers Suiting UpMaintaining SSA EquipmentGas ManagementField Neuro ExamsCommunicationsTimekeeping and TablesAssisting with Rescues Have more responsibilities than divers because they are responsible for divers.
Predive Environmental ChecklistKnow the dive depthsDive AltitudeWater temperatureUnderwater visibilityBottom typeHazards
Personnel to Run SSA Dive OperationsDiverTenderDive Supervisor*Standby DiverStandby TenderTimekeeper/Board OperatorBoat Operator*
Tender-Prior to WaterChecks the divers EquipmentDrysuitHarnessBailout systemManifold blockWeightingAir checkAGACommunication
Tender-Prior to WaterChecks air supply (bank)NuerosMaintains contact with the diver once he is dressedHelps diver to entry point
Tender-In the WaterCommunication CheckTakes care of divers umbilical CommunicationsAssists board operator with times and depth informationCan rotate between jobs, but only after his/her diver is out of the water
EmergenciesFoulingBlow upLoss of primary air supplyLoss of communications or contact
Postdive ProceduresHelp diver out of equipmentStow umbilicalsField NeurosPost dive maintenance on equipment
Timekeeper/Board operatorKeeps accurate records of dive timesDepthsNotes all important details of diveMonitors rates of flowCannot change job until ALL divers are out of water.
Supply Pressure Requirements-Demand SystemHelps eliminate low levels of CO2 Basic Formula for determining require air pressures:(depth in fsw X .445) + Manufacturers 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.
U.S. Navy TablesWhat 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.
Dive PlanningSingle Vs. Repetitive DiveSingle 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 DepthKnow Dive Schedule
Dive PlanningABT 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 diveeven if the diver is there momentarily.Dive Schedule refers to the combination of ABT and Depth as they appear on the table.
Dive PlanningStart of DescentActual Bottom TimeDive ProfileMaximum DepthStart of Ascent
NDLNo Decompression LimitsLeft side of the tableWhat is the NDL for 60 feet?What is the NDL for 100 feetWhat is the NDL for 140
Question?Can a team make a dive to 80 feet for 45 minutes?No. The NDL is 39 minutes
Repetitive DivesMore 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
Recording Repetitive DivesStart of DescentABTStart of Ascent/Schedule UsedEnd of ascent/start of surface intervalStart of descent/end of surface intervalSurface Interval Time (SIT)Repetitive letter groupRNT+ABTESDTDepthTime
Accounting For Residual NitrogenTable 9-7 Repetitive Group DesignationTable 9-8 Combination of two tables.Upper table depicts how the surface interval reduces excess nitrogenLower table shows how divers must account for this excess nitrogen on subsequent dives.
Dive PlanningAfter a single dive of 47 feet with an actual bottom time of 39 minutes answer the following questions:What is the Schedule used?50 / :41What is the repetitive group designation at the end of the dive?F
Repetitive Group After Surface IntervalThe longer the diver remains on the surface after a dive, the less residual nitrogen (RNT) will be present in the divers 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.
Repetitive Group After Surface IntervalDetermine 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 DesignatorThis 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.
Dive PlanningStarting with the last dive, our ending Repetitive Group Designator was F. What is the new designator after a 4:04 SIT?B
Determining Adjusted NDLAccounting for Nitrogen in the divers 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.
Dive PlanningContinuing with the previous dive, find the following with a dive to 46 for :22:What is the RNTWhat is the Adjusted NDLWhat is the ESDTWhat is the dive scheduleWhat is the new repetitive group designator?
Dive PlanningWhat is the RNT17What is the Adjusted NDL75What is the ESDT39What is the dive schedule50/41What is the new repetitive group?F
Determining the minimum surface intervalMust know the ESDT for the second dive. The ESDT will be the same as the NDL for the second dives max depthDeduct the teams 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 dives Group Designation to where the Repetitive Group intersects is the minimum surface interval
Dealing with AltitudeAny dive over 1000 feet in altitude is considered an altitude dive.All altitude dives need special tablesTraveling after an altitude diveChanges in gauges.
Ready for the Test?Need:Scratch paperCalculatorPencil
1. May have to dress differently because a lot of time on the surface in environmental conditions. The Tender should be able to operate with maximum efficiency throughout the dive. Reductions in the performance of the topside personnel could endanger the divers.Depths: How do you know?Temp: How do you know and why do you need to knowHazards: What type are there?All these things need to be in the dive briefing. If the supervisor doesnt state, then a tender better be asking before putting their divers in the water.Can Handle multiple jobs, but only after others are completed. Cannot handle jobs simutainously.During Surface supplied operations boat should be anchored by two points, so umbilical do not get tied up in boat. Perferably at the bow and sternThis is the minimum number of people to handle an operation.Is the suit on correctly. Is it completely zipped? Are the seals lying flat?Does the diver have one? Does he have a locking d-ring and shackle? Does the Shackle have a pull on it?Is it connected to the blockIs the block set on SSA or is it on the bailout system?Does the diver have weightsIs the divers air on?Is the seal on the AGA good? Does the purge work and the straps are adjusted?If you can, perform a communication check using the hard wire. Also review line pull signals.
Double check the board and bank to ensure your diver will have airField nueros prior to getting dressedWill always hold on to the diver, while the diver is dressed and on his feet. Helps diver to entry pointmay have to help with placing on fins.
May have to do this in the water first thing because of communication equipment. Also should practice line pulls.No excess slack or tensionBetween diver and supervisormay have to act as a go between.Back up for board operator. If they forget to write down timeIf you are not tendering your diver, you could switch between jobs. The new tender develops the relationship.Bring in NOAA manual