No-Decompression Limit (NDL)
Definition
The no-decompression limit is the maximum time a diver can spend at a given depth without requiring staged decompression stops.
More on No-Decompression Limit (NDL)
NDL is a critical concept in dive planning. Staying within this limit allows a diver to ascend directly to the surface at a safe rate. If exceeded, the diver must make mandatory decompression stops to avoid decompression sickness. NDLs depend on depth, gas mix, and prior dive profiles. Dive computers calculate NDLs dynamically, while dive tables offer conservative estimates based on square profiles.
Frequently Asked Questions
Dive computers use real-time tracking of nitrogen absorption. Tables use depth/time combinations and assume conservative conditions.
You must perform mandatory decompression stops during ascent. Skipping them increases the risk of DCS.
Yes. Surface intervals allow nitrogen off-gassing, extending NDLs for repetitive dives.
Yes, at certain depths. The reduced nitrogen content allows longer no-decompression times, but oxygen exposure must be monitored.
It's best to maintain a safety margin. Avoid pushing limits, especially on repetitive or deep dives.