Sorry to hog all the bandwidth on "DIR" stuff, but what the hell work is really boring...
Lost deco gas planning in RD...
Assumption:
EAN50 has a 50% time advantage over backgas deco
O2 has a 50% time advantage over backdeco (careful, O2 is not assumed to have a 50% advantage over EAN50)
Dive 150ft, 25mins
21/35 backgas
25mins deco on EAN50 + some deep stops
With all gases the profile (for me) would look like this, 13mins shallow, 12mins deeper:
10-5
20-8
30-2
40-1
50-1
60-4
70-4
80-1
90-1
100-1
110-30sec slide.
Assume lost EAN50 now in the context of the 2x advantage over backgas. A backgas version of this profile would have 50mins of deco shaped exponentially shallower. This is one technique but completely ignores the possibility of any EAN50 50% time advantage.
Instead you can do a bit of a hydrid, each sharing gas for the entire duration of the deeper stops where the "o2 window" (theoretically) exists. I.e. I do my complete stop on your bottle of EAN50, then you do your complete stop time while I am on backgas.
So each person would do:
10-5 on backgas
20-8 on backgas
30-2 + 2 on backgas
40-1 + 1 on backgas
50-1 + 1 on backgas
60-4 + 4 on backgas
70-4 + 4 on backgas
80-1
90-1
100-1
110-30sec slide.
Somewhere about the 30ft stop we'll assume the bottle runs out.
Net, this is the equivalent EAN50 deco:
10-5/2 = 2.5
20-8/2 = 4
30-2 + 2/2 = 3
40-1 + 1/2 = 1.5
50-1 + 1/2 = 1.5
60-4 + 4/2 = 6
70-4 + 4/2 = 6
80-1
90-1
100-1
110-30sec slide.
Ta da, the sum of that time is equivelant to 24.5 mins of EAN50 deco, essentially what you would have done on EAN50 if you hadn't lost it. A prudent diver would use the EAN50 until its gone, then depending on when it ran out pad the shallow stops fairly generously depending on how much backgas you have remaining. If you brought enough rock bottom you should have a fair bit in reserve still and can do the "full time" (4 & 8 mins in this example) of the shallow time. The EAN50 has only a modest deco advantage over backgas on the shallow stops anyway.
The same sharing 50% time advantage principle can be used on O2. If you need to I can elaborate on that in another post.
Lost deco gas planning in RD...
Assumption:
EAN50 has a 50% time advantage over backgas deco
O2 has a 50% time advantage over backdeco (careful, O2 is not assumed to have a 50% advantage over EAN50)
Dive 150ft, 25mins
21/35 backgas
25mins deco on EAN50 + some deep stops
With all gases the profile (for me) would look like this, 13mins shallow, 12mins deeper:
10-5
20-8
30-2
40-1
50-1
60-4
70-4
80-1
90-1
100-1
110-30sec slide.
Assume lost EAN50 now in the context of the 2x advantage over backgas. A backgas version of this profile would have 50mins of deco shaped exponentially shallower. This is one technique but completely ignores the possibility of any EAN50 50% time advantage.
Instead you can do a bit of a hydrid, each sharing gas for the entire duration of the deeper stops where the "o2 window" (theoretically) exists. I.e. I do my complete stop on your bottle of EAN50, then you do your complete stop time while I am on backgas.
So each person would do:
10-5 on backgas
20-8 on backgas
30-2 + 2 on backgas
40-1 + 1 on backgas
50-1 + 1 on backgas
60-4 + 4 on backgas
70-4 + 4 on backgas
80-1
90-1
100-1
110-30sec slide.
Somewhere about the 30ft stop we'll assume the bottle runs out.
Net, this is the equivalent EAN50 deco:
10-5/2 = 2.5
20-8/2 = 4
30-2 + 2/2 = 3
40-1 + 1/2 = 1.5
50-1 + 1/2 = 1.5
60-4 + 4/2 = 6
70-4 + 4/2 = 6
80-1
90-1
100-1
110-30sec slide.
Ta da, the sum of that time is equivelant to 24.5 mins of EAN50 deco, essentially what you would have done on EAN50 if you hadn't lost it. A prudent diver would use the EAN50 until its gone, then depending on when it ran out pad the shallow stops fairly generously depending on how much backgas you have remaining. If you brought enough rock bottom you should have a fair bit in reserve still and can do the "full time" (4 & 8 mins in this example) of the shallow time. The EAN50 has only a modest deco advantage over backgas on the shallow stops anyway.
The same sharing 50% time advantage principle can be used on O2. If you need to I can elaborate on that in another post.