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.
