Dive_Man_ChangeA

APPENDIX 1A — Safe Diving Distances from Transmitting Sonar Change A 1A-9 Example 2: You are planning a routine dive for 75 minutes using wet-suited divers without hoods at a dive site which is 1000 yards from an AN/SQS-23 sonar. The SPL was measured at 185 dB. The duty cycle for the AN/SQS-23 sonar is unknown. Is this dive permitted? Provide justification for your decision. SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET 1. Diver dress: Wet Suit - Un-hooded X Wet Suit - Hooded Helmeted ______ 2. Type(s) of sonar: AN/SQS-23 3. PEL Table 1A-3 X ; 1A-4 ; 1A-5 __; 1A-6 4. Range(s) to sonar (yards): 1000 5. Estimated SPL at range(s) in step 3 (from table/column in step 3): SPL = 185 dB Reminder: If range is between two values in the table, use the shorter range. If the SPL is measured at the dive site, use the measured value. 6. Depth Reduction 0 dB Reminder: 0 if not helmeted, see table in instructions if helmeted. 7. Corrected SPL (Step 5 minus Step 6) SPL1 185 – 0 = 185 dB 8. Estimated PEL at SPL (from table/column in step 3 of the appendix): PEL1 = 170 minutes 9. Duty Cycle Known: Yes ______ (do step 9); No X (stop) Adjusted PEL for actual duty cycle Actual DC % = 100 × _____ sec. (pulse length / _____ sec. (pulse repetition period) Actual DC % = ______ Adjusted PEL = PEL (from step 8) ___ min. × 20 / actual duty cycle (%) ___ = ___ min. Reminder: Do not adjust the PEL if duty cycle is unknown. 10. Multiple Sonars: Yes _____ (do step 10); No X (stop) Sonar 1: DT1 = (Desired dive duration) PEL1 = (from Step 8 or 9, as applicable) DT1/PEL1 = . Sonar 2: DT1 = (Desired dive duration) PEL1 = (from Step 8 or 9, as applicable) DT1/PEL1 = . ND = ____ + _____ = ____ (This is less than 1.0, so dive is acceptable and may proceed.) Reminder: The Noise Dose must not exceed a value of 1.0. The dive time of 75 minutes is permitted because the PEL is 170 minutes. Figure 1A-3. Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example).