c555
Contributor
Hi, I know this has been discussed before, but I have a question about rock bottom. I understand the whole concept, but in this article http://www.direxplorers.com/new-dir-articles/1376-rock-bottom.html, (sorry about it not being a link, you may need to copy+paste) it says that rock bottom, the amount of gas needed to got 2 divers to the surface safely, should always stay in your tank. In the first example it says that for a 60 ft dive on Al80's, the rock bottom is 400psi and they need to be on the boat with 400psi left. My previous understanding, which may be wrong, is that you could begin your ascent with 400 psi. My thinking is if you have a failure at 60 ft and you still have 400 psi in your tank, that is still enough to get two divers to the surface safely based on the calculations in the article. If nothing goes wrong and the dive goes as planned, then you should only end up using less than 200 psi for the ascent. If you end the dive with rock bottom in your tank, you could have a much shorter dive and reserve air that wouldn't be used, even in an emergency. I just want to know what way is right. Thanks