V-Planner

[Blackwood]

Change in calculating rock bottom time.
2 mins at bottom for emergency
30ft/per minute from bottom to 75% of depth
20ft/per minute from 75% depth to first gas switch
2 mins at gas switch depth for switch

Seems like an awful lot. For 50%- or O2-only dives sure, it's not that much (given the shallow switch depth). But for deeper bottles, 4 minutes (i.e. 2min/diver) gets to be a lot of gas.

Whomever has experienced the gas failure will be the first to switch, and that certainly shouldn't take 2 minutes, especially if they prepare for the switch (from as little as locating the appropriate bottle and ensuring it's charged to perhaps even deploying the hose so you can just plop in the reg when you reach the switch) at the next deeper level.

Right?

 

[Sloth]

Seems like an awful lot. For 50%- or O2-only dives sure, it's not that much (given the shallow switch depth). But for deeper bottles, 4 minutes (i.e. 2min/diver) gets to be a lot of gas.

Whomever has experienced the gas failure will be the first to switch, and that certainly shouldn't take 2 minutes, especially if they prepare for the switch (from as little as locating the appropriate bottle and ensuring it's charged to perhaps even deploying the hose so you can just plop in the reg when you reach the switch) at the next deeper level.

Right?

Since the deep stops went from 10ft per min to 20ft per minute I think its almost a wash. I believe the thinking is that Tech 1 means newbie deco divers so have them plan min gas this way.

Deploying the deco reg prior to switch depth was a big no no. I use to deploy on ascent from 60 to 70 or 30 to 20 so I had to break myself of that habit. I asked the question and the answer was not to have something around your neck that would get in the way of donating your breathing reg. Made sense to me so I wont be going back to pre-deploying.

 

[rjack321]

An extra min on the bottom and an extra one at the switch are pretty trivial to me, rock
bottom is just an educated guess on what you need to get an OOA diver up to a breathable gas (or surface) anyway.

lost 70' bottle
dont change the intermediate deco stop times but do switch off from back gas to buddies deco reg every 10 feet. Double the shallow deco times and continue to switch from back gas to buddies deco reg every 5 mins.

lost '20 bottle
Double the shallow deco times and continue to switch from back gas to buddies deco reg every 5 mins.

These rules are really obtuse to me. I wasn't taught anything like this by GUE nor UTD. Seems like something brand new.

 

[Rainer]

Seems like something brand new.

Definitely new.

Don't worry, though, I'm sure all past GUE students will be getting the e-mail any day now. Got to make sure we're all on the same page, you know. Yup, no worries...

 

[Sloth]

Definitely new.

Don't worry, though, I'm sure all past GUE students will be getting the e-mail any day now. Got to make sure we're all on the same page, you know. Yup, no worries...

I guess that's what they are trying to address with the SOP doc. Maybe they will update it and add lost deco procedures....or maybe not.

 

[Sloth]

An extra min on the bottom and an extra one at the switch are pretty trivial to me, rock
bottom is just an educated guess on what you need to get an OOA diver up to a breathable gas (or surface) anyway.



These rules are really obtuse to me. I wasn't taught anything like this by GUE nor UTD. Seems like something brand new.

Just to be clear this was if you are using only one bottle in Tech 1 ranges. I have no idea what lost deco procedures for Tech 2 ranges are and i probably didnt explain it right

 

[Rainer]

I guess that's what they are trying to address with the SOP doc. Maybe they will update it and add lost deco procedures....or maybe not.

Yeah, they did such a bang up job letting past students know there even was a SOP doc online (not like I learned about it in this thread, oh wait...), I'm sure they'll get right on letting us know about other changes.

In any case, what's the new procedure for both divers missing / having empty bottles?

 

[Sloth]

I guess an agency that emphasizes all divers diving from the same standards and protocols should do a better job of updating changes to past students. Maybe they will do a better job of that... or maybe not.

Im not sure what you are driving at with the silly question so I'll ignore it.

 

[Rainer]

Uh, it's not silly at all. Did you not learn procedures to deal with no deco bottles? I certainly know my buddy and I managed to kill our 40s once near the end of our 20' stop (rather new T1 divers, unexpected work due to currents, and new scooter) and had to finish off deco on back gas. Know many teams who have had to do the same (i.e. finish on back gas). I'm glad we had learned what to do in that case...

 

[rjack321]

Uh, it's not silly at all. Did you not learn procedures to deal with no deco bottles? I certainly know my buddy and I managed to kill our 40s once near the end of our 20' stop (rather new T1 divers, unexpected work due to currents, and new scooter) and had to finish off deco on back gas. Know many teams who have had to do the same (i.e. finish on back gas). I'm glad we had learned what to do in that case...

Rainer are you being sarcastic?

For a ~150ft Tech1 type deco dive with 50% for deco. Its not all that critical to finish the deco 20-10ft stops on the 50%. At that point in the profile you are using a pressure reduction to offgas, not the "O2 window" or a shallow EAD gas like 50%. Since you are using the pressure reduction to finish your deco and address the marginally loaded slow tissues you can complete the deco on backgas without any time penalty. If you really hoovered the 50% and/or ran out fairly deep (like at 40 or 50ft) you can start doubling the shallow stops on backgas. Obviously this transitions into a complete loss of backgas where (one) approach is to double the deco time and reshape the deco to an exponential decay curve.