• If a no-decompression limit is exceeded by 5 minutes or less: make an 8 minute stop at 15 feet and remain out of the water for 6 hours before diving again.
• If a no-decompression limit is exceed by more than 5 minutes: make at least a 15 minute stop at 15 feet and remain out of the water for a minimum of 24 hours before diving again.
When reviewing emergency decompression, here is some more food for thought:
• These rules are easy to memorize, but in an emergency situation, it is quite likely that a diver's memory may not be functioning at full capacity. It is a good idea to write this information down on a slate or even on the back of your computer so that you have access to it in the unlikely event of an emergency decompression situation.
• Consider the series of events that leads a diver to find himself in this sort of problem. While a diver may simply forget to check his computer or watch, another likely situation is that he needs to perform emergency decompression because of a computer or watch failure. Without a timing device, he may have no way to monitor the length of his emergency decompression stop. Unless his buddy is nearby, the only option left is to count out the minutes. Divers should be prepared for this possibility.
• Most regulators have an analog depth gauge, but in an absolutely worst-case scenario, a diver relying only on a computer could find himself with no idea of his dive time or depth. In this situation, an observant diver may be able to visually estimate his depth, but most divers would be hard pressed to hold themselves at exactly 15 feet with no depth gauge. At this point, the diver should make his best guess and estimate. Emergency decompression imperfectly done is still better than no emergency decompression at all.
• Emergency decompression can only be performed as long as the diver has air left in his tank. This is yet another reason to always dive conservatively, and to plan to surface from a dive with plenty of gas in reserve.
Of course, divers would do best to avoid an emergency decompression situation altogether. Plan for an equipment failure by carrying a back-up timing device and an analog depth gauge, and by making a dive plan based on the recreational dive tables in case of a computer failure. However, even the best divers can make mistakes, and sometimes events simply conspire against you. By understanding the rules of emergency decompression, a diver is prepared for this possibility and can remain safe and confident in even the worst of situations.