Nitrogen Man Scuba Calculator

Nitrogen Man Dive Calculator – Description & User Guide

What It Does

The Nitrogen Man calculator is both a training simulator and a practical dive planner. It helps divers visualize and track nitrogen loading, no-decompression limits (NDL), oxygen exposure, and overall safety margins in real time.

It adapts U.S. Navy–style NDLs with a 5% conservative buffer, creating Maximum Dive Limits (MDL), while also supporting Bühlmann ZH-L16C + Gradient Factors for true decompression profiles. This dual approach makes it useful for:

• Single dive planning – See your MDL or full decompression schedule for a chosen depth.
• Repetitive dives – Track residual nitrogen, surface intervals, and automatic carry-over between dives.
• Risk awareness – Monitor nitrogen index (NI%), oxygen partial pressure (ppO₂), and safety stop or deco requirements.
• Visual training – A “Nitrogen Man” graphic fills and clears to show loading/unloading of nitrogen during the dive sequence.

How to Use It

1. Set Dive Depth  Enter your planned depth (in meters) in the “Depth” column for each dive row.
2. Enter Dive Time  Type your Planned Bottom Time (PBT) in minutes, or use “Use Plan” to import from a previous line.
3. Surface Interval (SI)  For repetitive dives, input your SI in minutes. Residual nitrogen time (RNT) adjusts automatically.
4. Review Key Outputs  - RNT: Residual Nitrogen Time carried forward.  - TBT: Total Bottom Time (RNT + PBT).  - NDL / MDL: Remaining no-decompression or maximum limit at depth.  - ppO₂: Oxygen exposure based on FO₂ entered.  - NI%: Nitrogen Index – percent of modeled capacity used.  - Stop: Minimum safety or deco stop time.
5. Watch the Nitrogen Man  The diver graphic fills with nitrogen during dives and empties during SI, a quick visual cue of loading.
6. Risk Assessment Panel  Displays “Low,” “Moderate,” or “High” risk ratings using nitrogen load, oxygen exposure, and optional environment data.

Tips for Best Use

• Always round up depth and time to the next higher value.
• Include a minimum 3-minute safety stop at 5 m (15 ft), or follow the stop schedule shown.
• Remember: this is for planning and training—dive within your certification and conditions.
• Cross-check results with your dive computer and follow whichever is more conservative.