If you did your PADI Open Water Course before 2013 you learned how to dive with the RDP table, the eRDPml or if it was in the 90’s by the wheel. But after 2013 most of the divers learned, if it was applicable, to dive with a computer. Why is that? Those tables give you a theoretical depth and to be honest if we plan our dive to 18 meters while doing a 50 minute dive, I don’t think anyone out there will stay strictly on 18 meters as there is always something nice to see on 16, 12 or even on 5 meters towards the end of the dive. A computer is just way user friendly as it starts and stops automatically and gives actual decompression times.