Your first dive is to 60 ft for 50 minutes. After spending one hour and 40 minutes on the surface, what is your adjusted maximum dive time at 60 ft?

When planning dives, it’s important to consider the repetitive dive limits and surface intervals that impact your allowable bottom time for subsequent dives. After your first dive to 60 feet for 50 minutes, a surface interval of 1 hour and 40 minutes allows for some decompression to take place.

From the tables used in diving (like the RDP - Recreational Dive Planner or dive computers), we can estimate that the longer your surface interval, the more "time" it gives you before your next dive regarding nitrogen off-gassing from your body.

In this specific case, after your first dive, there is a "no surface interval" time for a repeat dive at this depth. The precise adjusted maximum dive time for a follow-up dive is calculated based on your previous dive profile and the amount of time you have spent at the surface. Therefore, after a surface interval of 100 minutes, you would be able to extend the bottom time on the next dive to around 19 minutes at 60 feet, which is in line with the guidelines that help prevent decompression sickness.

This understanding is crucial for safe diving practices, ensuring that divers do not exceed their limits and maintain a safe nitrogen loading level in their bodies.