Divers FAQ's
eRDPml & Nitrox eRDPml
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eRDPml & Nitrox RDP
eRDPml
eRDPml (Recreational Dive Planner Multi Level) – The Recreational Dive Planner (RDP) is a decompression model and dive planning tool developed by PADI (and commonly used in many recreational diving programs) to help divers plan bottom time, depth, and required safety stops to stay within no-decompress or limited-decompression limits. It provides a structured way to estimate nitrogen loading and to determine safe ascent profiles.
Key components typically found in the RDP concept:
- Depth and bottom time grids: A set of tables or a calculator that maps maximum allowable bottom time at various depths to avoid decompression obligations.
- No-decompression limits (NDLs): The maximum time you can stay at a given depth without needing mandatory decompression stops during ascent.
- Decompression planning: If a dive exceeds NDL, the planner suggests decompression stops at specified depths and durations to safely off-gas inert gases.
- Surface interval planning: Guidelines for how long you should wait before the next dive to off-gas nitrogen and reduce residual Nitrogen Time (RNT) on subsequent dives.
- Residual Nitrogen Time (RNT) or repetitive dive planning: Adjustments to NDLs based on previous dives within the same day or consecutive days.
- Gas loading considerations: Rules of thumb for how much gas to reserve for ascent, safety stops, and contingencies.
- Safety stops: Recommendation to pause at about 3–5 meters (10–15 feet) for a few minutes to off-gas nitrogen, even on no-decompression dives.
- Dive profile recording: A place to note depth, time, surface interval, and planned vs. actual dive data for post-dive review.
How it’s used in practice:
- Determine your planned depth and bottom time for a dive.
- Look up or compute the NDL for that depth.
- If your planned bottom time is within the NDL, plan a safe ascent with a safety stop.
- If your bottom time exceeds the NDL, plan a decompression dive with required stops at specified depths and durations.
- After surfacing, calculate the surface interval before the next dive to reduce residual nitrogen time.
Common formats:
- Table-based RDP (the classic five-column or four-column no-decompression tables), sometimes color-coded for quick reference.
- Electronic or mobile-app versions that implement the same logic but with input fields for depth and bottom time and automatic calculation of NDLs, decompression stop requirements, and surface intervals.
Important note:
- The RDP is designed for recreational diving up to about 40 meters (130 feet) and assumes standard breathing gas (air). Technical dives or gas mixtures require different models (e.g., Bühlmann, VPM, RGBM) and training.
- Always use current, regionally appropriate tables or approved digital tools, and follow your training agency’s procedures.
Designed for recreational dives up to ~40 meters (130 feet) on air; not for technical or mixed-gas dives.
eRDPml
Recreational Dive Planner
RDP emphasizes staying within (NDLs) or planning required decompression stops if limits are exceeded, plus surface interval planning. RNT adjustments account for repetitive dives, and optional safety stops help off-gas nitrogen.
Nitrox eRDPml
Nitrox is a breathing gas used in scuba diving that contains a higher proportion of oxygen than atmospheric air. The most common mixes are EANx (enriched air nitrox) with oxygen fractions of 32% or 36%, though blends from about 21% to 40% oxygen are used in some dives.
By increasing the oxygen content and reducing the nitrogen portion, Nitrox can reduce nitrogen absorption in the tissues, which can extend no-decompression limits and shorten surface intervals on recreational dives. However, higher oxygen levels increase the risk of oxygen toxicity, especially at deeper depths, soNitrox is typically recommended for shallower recreational dives (often up to 30–40 meters, depending on the mix and training). Key concepts:
- EANx percentages: common are 32% and 36%.
- MOD (Maximum Operating Depth): deepest depth at which a given mix can be breathed safely to avoid oxygen toxicity.
- Benefits: longer bottom times, shorter surface intervals (in some scenarios), reduced nitrogen loading.
- Trade-offs: reduced bottom gas supply due to lower nitrogen, need for careful dive planning and training, and enhanced O2 toxicity awareness.
Nitrox eRDPml
Recreational Dive Planner
You typically need an appropriate Nitrox certification (often called Enriched Air Nitrox {EANx}) to dive with these mixtures, learning about depth limits, analyzing gas, and how to plan dives with Nitrox.