OK, first contact - lots to see here - I'm a novice, 3rd week of PADI OWD course, with aims of warm water diving rather than diving in UK .... I've a query on the RDP from the quiz - 'What is the minimum surface interval required betwen a dive to 20metres/ 70 feet for 29 minutes followed by a dive to 14 metres/ 50 feet for 39 minutes?' - This doesn't compute on the RDP so I am guessing that the safe option is at least 3hours - but is there a way to compute this? I'll tell you more about me on next visit .... Ross567