Hi there, just doing my homework from dive 5, and I was wondering if anyone can confirm my answer to a question. I'd normally wait for my tutor to point me right, but I'm doing the test tonight, and if this is wrong then I need straightening out.
Q: What is the minimum surface interval required between a dive to 20 metres/70 feet for 29 minutes followed by a dive to 14 metres/50 feet for 39 minutes.
A: zero minutes. (I hope)
edit: ok, a bit of working out:
1/ first dive puts you in pressure group M.
2/ 2nd dive has 59 minutes of residual nitrogen available at 14 metres. (to make a total of 98 mins, NDL@14 meters)
3/ to add 57 mins of residual at 14 meters, I'd need to be in PG:P
4/ Since a SI is never going to take me from PG:M to PG:P, the SI _required_ is 0 minutes.
Many thanks for your thoughts I have a dunce's hat on standby.