Lamby... did you have a computer before the xDeep that had an NDL planner?
I'm trying to figure out when, as a recreational EANx diver, you would use this and how?
I learned it the tables and planning when I took the PADI Nitrox course, but I'm not sure I've ever seen a situation where I'm going to use it.
I observe my NDL.. if I go upside down a few minutes I'll burn it off during my ascent. It's not the end of the world. I supposed that's technically deco diving, but then again so is any rec dive if you're forced to make a "safety stop" (which is really recreational speak for "deco stop").
If it's a matter of not understanding what going into deco really means, I get that. I used to think going into deco was some horrible thing. Now I realize it just means I'll have to wait a few minutes longer before surfacing, and more often than not I burn it off during my return/ascent anyway, so I never really notice it.
If you're drastically running your air down and have no concept of what your SAC rate is, I wouldn't recommend going this route, but generally speaking, if you're a by the book PADI recreational diver and you're making sure to start your return at about 1,500psi, you will more than likely have ample gas for a few minutes of deco.
Since you're only diving EANx, what exactly are you looking to plan that your computer isn't able to tell you during the dive?
Regardless of how many back-to-back dives you're doing, you have to do a surface interval.
If you're doing NDL, that infers no deco stops. So are you simply trying to figure out before your next dive how long your bottom time will be at depth?
Something else to consider, though I haven't done it yet... As I understand it, even with an unplanned dive you can switch your gases on your computer to a higher % of O2 (if you're slinging an second bottle) during a stop (before surfacing) to bring the bottom time up for your next dive. Your computer should take this into account in conjunction with your surface interval.
I dive a Petrel and haven't used all of the features it has, to include the dive planner, partly because I wait the hour surface interval and partly because I'm comfortable with a few minutes of unplanned deco.
I honestly think you should give the xDeep more of a chance, but again, I don't know what kind of diving your doing that you feel that an NDL planner is absolutely necessary.
Having said that, I'm actually surprised the xDeep doesn't have the NDL Planner as an option. As I understand it, it is at its core an advanced bottom timer, so I guess that should be expected. I would think if it's something you can calculate on a table or is already available in other computers, why would be it difficult to incorporate it into this computer? The NDL planner on the Petrel is really just a quick look version of what you would get from doing tables. You select how long before your next dive and it breaks your times down by the gas you currently have selected and depths. The Dive Planner, and again I'm assuming, is probably something you're no going to get much use out of if you're sticking to NDL and only diving a single gas.
So... I don't know that this helped much. Don't take everything I say as gospel. There are some that may agree with what I wrote and some who will adamantly disagree and tell me I don't know what I'm talking about, which is certainly possible. I'm always learning more every day.
I currently don't use the feature you want. Not to say I never will, but I don't see any need for it in my foreseeable future and I dive at least 1-3x/week.
