46 C.F.R. § 197 app A to Part 197
The following table gives the depth versus bottom time limits for single, no-decompression, air dives made within any 12-hour period. The limit is the maximum bottom time in minutes that a diver can spend at that depth without requiring decompression beyond that provided by a normal ascent rate of 60 fsw per minute. (Although bottom time is concluded when ascent begins, a slower ascent rate would increase the bottom time thereby requiring decompression.) An amount of nitrogen remains in the tissues of a diver after any air dive, regardless of whether the dive was a decompression or no-decompression dive. Whenever another dive is made within a 12-hour period, the nitrogen remaining in the blood and body tissues of the diver must be considered when calculating his decompression.
Air No-Decompression Limits
| Depth (feet): | No-decompression limits (minutes) |
| 35 | 310 |
| 40 | 200 |
| 50 | 100 |
| 60 | 60 |
| 70 | 50 |
| 80 | 40 |
| 90 | 30 |
| 100 | 25 |
| 110 | 20 |
| 120 | 15 |
| 130 | 10 |
(Source: U.S. Navy Diving Manual, 1 September 1973.)
46 C.F.R. 197 app A to Part 197
Source: U.S. Navy Diving Manual, 1 September 1973.