pt40fathoms:
We follow the guidelines set out by PADI, QUOTE]
PT - what is the minimum depth for the deep dive in PADI guidelines? I thought the deep dive was meant to be to around 30m but I was speaking with someone who only went to 22m. This was something to do with the conditions on the day and maybe understandable in that context but I think there is quite a difference between 22m and 30m, particularly the potential degree of narcosis. Also pyschologically and for confidence building. My AOW deep dive registered 29.9m on my computer!
There would most certainly be a difference, however the object is not to push it to the maximum, merely to arrive at a depth that will meet the needs of the required demonstration. Your dive to 29.9m was at the high end of what is set out in the PADI standards, and the dive to 22m is near the depth we work at. It really matters what the conditions are like, and they include but are not limited to water temperature, air temperature, surface conditions, visibility at depth, time of day, and so on. I just posted that we have a plateau at 77 feet (23.5m) and because of that our depth for this dive tends to be consistent. However that's not always the case, and I would suspect it would be more the exception than the norm. So most instructors have to deal with changing conditions to a higher degree than we would if the training site has less underwater features that can aid them.