| WHAT DOES THE CHART HELP THE USER VISUALIZE? | ||||||||||||||||||||||||
| At a given depth, will I run out of gas or incur a deco obligation first? Air? EANx32? EAN36? | ||||||||||||||||||||||||
| Why doesn't Nitrox extend my bottom time at depths less than 60 or 70 feet when using a single tank (80 cf - 100 cf) | ||||||||||||||||||||||||
| For a given depth, how much more bottom time will EANx32 give me? EANx36? | ||||||||||||||||||||||||
| Can I get bent on air at 50 fsw on a single tank? How about using doubles? | ||||||||||||||||||||||||
| ASSUMPTIONS | ||||||||||||||||||||||||
| 1) | The graphs plot Max NDL for Air, EANx32, and EANx36 (Genesis Algorithm which is similar to PADI Table #1) | |||||||||||||||||||||||
| 2) | Assumes a single square-profile dive (no previous N2 loading) | |||||||||||||||||||||||
| 3) | The graph on the right is just a close-up of the lower right portion of the graph on the left. | |||||||||||||||||||||||
| 4) | The shape of the red line is fixed by Boyle's Law | |||||||||||||||||||||||
| 5) | The vertical position of the red line on the graph depends on an individual's gas consumption rate and/or | |||||||||||||||||||||||
| the volume of breathing gas available | ||||||||||||||||||||||||
| 6) | A better gas consumption rate and/or a greater volume of breathing gas means more bottom time, | |||||||||||||||||||||||
| so the red line could be higher than shown | ||||||||||||||||||||||||
| 7) | A worse gas consumption rate and/or a lesser volume of breathing gas means less bottom time, | |||||||||||||||||||||||
| so the red line could be lower than shown | ||||||||||||||||||||||||
| 8) | Above a particular gas line, you may incur a deco obligation | |||||||||||||||||||||||
| 9) | Above the tank line you are out of breathing gas | |||||||||||||||||||||||
| EXPLANATIONS | ||||||||||||||||||||||||
| The "Bottom Time" at a given depth is calculated based on a diver's Surface Air Consumption (SAC) rate and the capacity of the diver's tank(s). | ||||||||||||||||||||||||
| The User can change his SAC by changing his breathing rate (breaths per minute) and/or his lung volume (volume per breath). | ||||||||||||||||||||||||
| The User can choose the volume of gas available (in cubic feet). For example, a diver using twin 80s would have a nominal 160 cf of gas available. | ||||||||||||||||||||||||
| The red "Tank Limit" line is nothing more than a graphic representation of Boyle's Law (volume is inversely proportional to pressure). If you have a full tank on the surface, you will breathe the tank dry in some number of minutes. All things being equal, at 33 fsw, you will breathe the tank dry in half the time. At 99 fsw you will breath the tank dry in one quarter of the time. | ||||||||||||||||||||||||