How is time-to-surface (TTS) calculated?

The time-to-surface (TTS) is a crucial calculation in diving that helps divers manage their ascent times and overall dive safety. It represents the total time it will take for a diver to return to the surface from their current depth, accounting for the necessary ascent and any safety stops.

The correct calculation involves determining how much time is spent underwater, primarily focusing on two essential components: the bottom time and the ascent time. Bottom time refers to the duration spent at the maximum depth of the dive. Ascent time is then determined by considering the safe rate of ascent, including any mandatory stops for decompression if required.

In choosing the correct answer, it’s vital to know that the total runtime consists of the complete duration of the dive, including both the bottom time (time spent at depth) and the ascent time (time taken to return to the surface). To find the time-to-surface, TTS is effectively calculated by subtracting the bottom time from the total runtime, as this shows the diver how much time remains to reach the surface after accounting for the descent.

Understanding this calculation is critical for maintaining safe diving practices and preventing decompression sickness by ensuring that the diver ascends within safe time limits.