dive planning @ 300' cont.from D&T

[IDS_Bill]

This is not a bad dive plan IF you have support divers who can bring you gas if you have a lost gas situation. Your Back Gas volume is okay, your PPO2 and END are okay. You have to assume that you will not have the O2 if it is hanging though (you would do two profiles for with and without) and you have to deal with the lost gas scenario. Would I do it on 80's? Sure - If I kept the deco bottles clipped to me at all times and had a support diver and had a no current situation and....... You get the picture.

Trimix dives are always tricky and require support. When you leave the bottom and your computer is reading 999 minutes of deco (based solely on current breathing gas - NitekHe) the reality sinks in. Always have a support diver for dives like this.

 

[walke121]

Really great thread guys. Very interesting to me. Its nice no one is arguing over it too.

 

[rjack321]

Trimix dives are always tricky and require support. When you leave the bottom and your computer is reading 999 minutes of deco (based solely on current breathing gas - NitekHe) the reality sinks in. Always have a support diver for dives like this.

Call us foolish but we only add a support diver when we: get over about 80mins of runtime. Or need to communicate with the boat (like on a drift and the skipper needs to know all are accounted for and there's no lone SMB out there).

We don't use computers so I don't have these supposed 999min things flashing at us.

 

[rjack321]

I know the OP said .4, but that's just off in fantasy land for me in a drysuit and 4 tanks.

This probably the most unrealistic assumption anyway. It might be 0.4 on good days, but when the excrement hits the fan I would not plan on it staying at 0.4

Overall the plan would be vastly improved with a bottom stage of the 12/60, a deeper deco gas with He in it, an intermediate deco gas, and O2

 

[Kevrumbo]

This probably the most unrealistic assumption anyway. It might be 0.4 on good days, but when the excrement hits the fan I would not plan on it staying at 0.4

Overall the plan would be vastly improved with a bottom stage of the 12/60, a deeper deco gas with He in it, an intermediate deco gas, and O2

It's doable in warm tropical water, but I would plan it using 0.5 cfm/15 lpm, and use 0.75 cfm/28 lpm for MGR planning.

 

[Cave Diver]

This probably the most unrealistic assumption anyway. It might be 0.4 on good days, but when the excrement hits the fan I would not plan on it staying at 0.4

Overall the plan would be vastly improved with a bottom stage of the 12/60, a deeper deco gas with He in it, an intermediate deco gas, and O2

That's one of the reasons why I said "no" to the "would you do this dive" question. Part of dive planning is knowing your limitations and I know that .4 is unrealistic for me. Keeping everything else the same, it's possible that this dive could be done, but there is no way that I could do it.

 

[rjack321]

yeah planning for you best consumption during your worst nightmare is a bit bold for me as well.

Bringing alot more gas is really not that big a deal. If I were diving al80s and no 40s were available, I'd have another 80 of 12/60, probably an 80 of 21/35, and 80 of EAN50 and O2. Thus the doubles + a bottom stage plus 3 deco bottles. Although for 10mins at 300ft its hardly worth all this effort to me unless I could deco up a really cool wall or something. If the deco were midwater I'd pass for sure. If it were in my local 48F waters I'd also pass.

 

[IDS_Bill]

Call us foolish but we only add a support diver when we: get over about 80mins of runtime. Or need to communicate with the boat (like on a drift and the skipper needs to know all are accounted for and there's no lone SMB out there).

We don't use computers so I don't have these supposed 999min things flashing at us.

Whatever floats your boat - who am I to call you foolish.

 

[ianr33]

Although for 10mins at 300ft its hardly worth all this effort to me unless I could deco up a really cool wall or something. If the deco were midwater I'd pass for sure. If it were in my local 48F waters I'd also pass.

That is the advantage of Cayman The walls are a lot cooler than the water

 

[Cave Diver]

That is the advantage of Cayman The walls are a lot cooler than the water