1A-4 Change A U.S. Navy Diving Manual—Volume 1 SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET 1.    Diver dress: Wet Suit - Un-hooded Wet Suit - Hooded Helmeted 2.    Type(s) of sonar: 3.    PEL Table 1A-3 ; 1A-4 ; 1A-5 ; 1A-6 4.    Range(s) to sonar (yards): 5.    Estimated SPL at range(s) in step 3 (from table/column in step 3): 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 dB Reminder:  0 if not helmeted, see table in instructions if helmeted. 7.    Corrected SPL (Step 5 minus Step 6) 8.    Estimated PEL at SPL (from table/column in step 3 of the appendix): 9.    Duty Cycle Known: Yes (do step 9); No (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. PEL1 = minutes; PEL2 = minutes Reminder: Do not adjust the PEL if duty cycle is unknown. 10. Multiple Sonars: Yes (do step 10); No (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. Figure 1A-1.  Sonar Safe Diving Distance/Exposure Time Worksheet.