Deco dive with divers on different back gas

[ChuckP]

Most rediculous comment of the day. I use air for deco dives at 100 feet or deeper.

I thought the same thing until I realized this was posted in the DIY forum

 

[Blackcrusader]

People have too much gear, this should be moved to the basic forum. A 15ltr tank of air will give you 35 minutes at 100 feet with a 10 minute stop at 10 feet

So will an AL80

 

[DiveLikeAMuppet]

People have too much gear, this should be moved to the basic forum. A 15ltr tank of air will give you 35 minutes at 100 feet with a 10 minute stop at 10 feet

So will an AL80

Not sure what you are diving but even US Navy tables for fit young divers would give you 15 minutes. Buhlmann with ?/85 is closer to 30 minutes of deco.

 

[rddvet]

TDI AN/DP divers use air to that depth and deeper.

Doesn’t mean it’s a good choice.

 

[Celt]

So will an AL80

I like to have enough,

 

[Blackcrusader]

I like to have enough,

Well if you end the dive with more than 30 bar in your tank then you had enough.

 

[Celt]

Not sure what you are diving but even US Navy tables for fit young divers would give you 15 minutes. Buhlmann with ?/85 is closer to 30 minutes of deco.

I was being generous and padded the 3m stop 10 minutes

 

[crofrog]

So when 2 divers up with 18/45 and 21/25 for a 150 dive do they just buddy up casually too? Where does this slippery slope end? Part of making a deco dive <PLAN> is ensuring you're both doing the same dive and here we have 2 divers deviating from one of the basics before they even get to matching rock bottoms, potentially with dissimilar tanks, or mismatched stressed SACs, OOA plans, or anything else. It's a same ocean dive, just go solo if not having a common plan is that trivial.

I’ll preface by saying that I prefer all divers to be on the same gas, and I’d prefer to not use a more expensive mix than required for a given objective.

That being said we would just determine the controlling parameters for the mix.

In this case we’d be unable to do the 150ft dive because of gas density of 21/25 at 150ft has an EADD of 112ft.

If we decided to do a 130ft dive just generate the schedule with deco planner with 18/45 as that’s the controlling gas for the decompression.

 

[Wibble]

I’ll preface by saying that I prefer all divers to be on the same gas, and I’d prefer to not use a more expensive mix than required for a given objective.

That being said we would just determine the controlling parameters for the mix.

In this case we’d be unable to do the 150ft dive because of gas density of 21/25 at 150ft has an EADD of 112ft.

If we decided to do a 130ft dive just generate the schedule with deco planner with 18/45 as that’s the controlling gas for the decompression.

That’s 18/45 on a rebreather? It’s a phenomenal waste of good helium for open circuit; 45m/150ft is a 25/25 dive on OC, or just use 25% and put up with the narcosis.

 

[LFMarm]

Well if you end the dive with more than 30 bar in your tank then you had enough.

30 bar after 1 emergency is enough, not after a planned dive – as we are in the technical diving forum. Unless you want to plan for water ingress in your tanks, you should make a plan that in case of an emergency (e.g., loss of gas of your buddy if you do team planning, or your own primary gas if you plan for solo) allows you and your buddy to get out of the water with 20-30 bar, while experiencing increased SAC under stress.