[Step]

I would very much like to know:
(I have no access to planning tools other than BSAC88/Nitrox table and my Air only Aladin Pro so can’t look this up for myself.)

1.
A. How much bottom time in the 30-50m range can I get using 1-2 deco mixes and 30%-21% as back gas while keeping deco to 15 min or less.
Or what is the max. depth I can still get 30 min of bottom time when doing 15 min deco or less.
B. Same question but with air as back gas and 100% for deco only.

2. How effective is accelerated deco. i.e. does it make sense to use it to cut
10 min deco down to say 5 or is it only adequate to cut 40min to 20min?
Or in other words by what percentage can I cut my deco time.
(I plucked those numbers out of the blue and am not sure how realistic they are but you get the drift)

3. How realistic is to everything on air as a back gas I stage with100% O2 for deco?
Then I would only need to O2 clean one reg. an no cylinders as the one would always get 100%. I also won’t need an analyser as everything I will ever use will be 100% or 21%. (Temporarily at least until I move back to where I can get up to 40 pre-mixed and then would buy an analyser)


I guess the above depends on how conservative I want to be. The answer is not very.
I’m interested in what you’d be happy with, for now, and will decide what level of risk I’m happy with after I have done the course.
(as I’m not sure how conservative what I’m doing now is maybe that would be a good reason to do the course already?)


Why am I interested
I’m thinking of doing the BSAC extended range course. Manly to learn about accelerated Deco.
(If there is another reason why I should want to do this course I would be interested to hear that as well)
I’m sure the course will be very interesting but if I’m unlikely to use what I learned I rather spend the money/time on a weekend away diving.

I did the BSAC advance nitrox course and although it was very interesting so far it has just been an expensive waste of money.
I have not used nitrox in the 2 years since because my diving does not justify paying 8quid for a fill, never mind the cost of a, personal filter, nitrox analyser, and annual O2 cleaning of cylinders and regs. I would definitely use it on the odd occasion if only I could get pre-mixed up to 40% round here.

So far I have dived to see sea creatures so I could just chase the no-deco limit up the slope and don’t have to do deep as most of the time, most live is shallow, and the most interesting is below the kelp but above the mud...
Now I want to have a look at some wrecks, but to be of interest as a wreck rather than because they support lots of live, they need to be very intact! This usually means deep and ascending through the water column with nothing interesting to look at.
If I don’t get 30 min bottom time all the preparation and expense for the boat etc. is not worth it in my opinion so with my sinus issues I tend to descend slow => so this means a dive time of >40min. if the dive goes below 25m.
Although I have no trouble in holding a stop I get bored on the 3 min safety stop. Now for a superb dive I guess I’d be happy to hang for 5min but I doubt I have the patients for longer than15.
I want to dive what is local and not have to travel all over the country to find intact wrecks in my depth range. I.e. adjust the diving to the wreck I want to dive not fit the dive site to the dive I want to do (within reason oc course).