Increasing conservatism with Decoplanner/VPM

[ucfdiver]

I'm not overly keen on spending 15 minutes on O2 at 1.6 PP... and taking a 5 minute air break isn't going to fit the overall schedule very well IMO. I'm thinking I'll try a few things:

a. extending the O2 stop (12 minutes max?)

b. slowing the ascent for the last 6m

c. staying on O2 for the ascent

I'll mix & match until I find something that works both in eliminating any symptoms & being practical. Might be hard to know what works since most of my dives have been asymptomatic... actually I believe the schedules I use are "okay" but maybe on the edge of what works for me - so that if I'm not fully hydrated, or doing multiple dives, or carrying gear etc, I get a problem

My rule is 15min on 5 off, unless it's 20-25min, then I just stay on. I count the 5 off as part of the o2 time. I also maintain a 1.2 avg or less bottom ppo2, so if you're running it hotter than that, things could work differently.

 

[Tortuga68]

My bottom PPO2s can run a little higher than that...

What depth/s are you doing your O2 stop/s at, 10/20'?

 

[ucfdiver]

My bottom PPO2s can run a little higher than that...

What depth/s are you doing your O2 stop/s at, 10/20'?

I do all my o2 time at 20ft, followed by a 3-5min ascent to the surface. For short deco dives (<10min), I'll skip the slow ascent and just do 1 minute or so. For dives in the 45min of deco range, I'll do 5min.

 

[rjack321]

We do 10-on, 5-off for O2 unless its 20mins or less in which case we do the full time with no break. All the O2 time at 20ft/6m then a 5min ascent.

However...
We also use a lower bottom ppO2 (not diving air, we use 18/45 for 55m saving our 1.6 ppO2 clock for the deco but not using much of it at depth).
And we don't shape the EAN50 time like you do (we weight the 70ft/21m stop more and the 30ft/9m stop less).
And we take a backgas break onto the lowest O2 content gas we can before going onto O2 (in this case onto 18/45).



Based on your symptoms, I still think you are not offgassing the slowest tissues enough with only 10mins at 20ft/6m. That's only like ~5 blood circulations, not enough for slow fatty tissues like skin. Even if you do 10on, 5off, 5on O2 for ascent that is alot more time than currently. Its not just what gas you're breathing but adequate time is a huge variable on these short bouncy dives (20mins is short in the grand scheme of things).

 

[Tortuga68]

I understand the logic of what you're saying, and I'm inclined to agree on the proposed solutions, which I will try as outlined above. At the same time there are two points I'm also considering:

1. I doubt my buddies are going to change their profiles, so I don't really want to extend my time too much beyond what they'll be doing. Not that I'm going to bend myself just because they're already on the boat, or that they won't wait, but you know... within reason

2. The guys I dive with pretty much all run the same profiles, and some of them have been doing so for a mighty long time & hundreds if not 1000s of tech dives. Which is not to say that it's right, current or will work for me, but they've never been bent (or been treated for it anyway), which seems to say they do work (for them)

So I'm happy to change my profile but I believe I can probably find something that works for me which isn't too far from where I started

 

[ucfdiver]

1. I doubt my buddies are going to change their profiles

GI3 upset a lot of people, but rule #1 isn't bad advice. I'd much rather make a buddy wait an extra 10min than continue getting bent.

 

[TSandM]

Wow . . . if my buddies refused to adjust their deco profiles to help me avoid DCS, I'd really rethink diving with those buddies. Not ONLY does that show a profound selfishness, in my view, they are also taking the chance of having to run a rescue scenario on the boat (no guarantee your symptoms will remain minor!)

 

[down4fun]

I understand the logic of what you're saying, and I'm inclined to agree on the proposed solutions, which I will try as outlined above. At the same time there are two points I'm also considering:

1. I doubt my buddies are going to change their profiles, so I don't really want to extend my time too much beyond what they'll be doing. Not that I'm going to bend myself just because they're already on the boat, or that they won't wait, but you know... within reason

2. The guys I dive with pretty much all run the same profiles, and some of them have been doing so for a mighty long time & hundreds if not 1000s of tech dives. Which is not to say that it's right, current or will work for me, but they've never been bent (or been treated for it anyway), which seems to say they do work (for them)

So I'm happy to change my profile but I believe I can probably find something that works for me which isn't too far from where I started

IF your buddies give a rats a$$ about you, waiting an extra few minutes is no big deal.

The problem with decompression planning is no one really knows for sure what will work for who on what day. And just because they (your buddies) have never taken a chamber ride doesn't mean they haven't had symptoms and like yourself blown if off to some other cause. Between the denial surrounding DCS and the ego of running minimal conservatism about half of what you hear is BS.

I hope you find a solution, since according to your opening post you have already been symptomatic multiple times. Your pushing the odds IMHO.

 

[rjack321]

Wow . . . if my buddies refused to adjust their deco profiles to help me avoid DCS, I'd really rethink diving with those buddies. Not ONLY does that show a profound selfishness, in my view, they are also taking the chance of having to run a rescue scenario on the boat (no guarantee your symptoms will remain minor!)

110% agree. Even the fact that you (tortuga) aren't sure if they give a damn is a huge red flag for me. I don't even get in the water with people I suspect are that flippant about my well-being. So far, most of us have been talking about ~10min changes, if those are "deal breakers" you need better friends.

 

[Tortuga68]

Thanks everyone for your input on changing my deco profile

GI3 upset a lot of people, but rule #1 isn't bad advice

Don't forget that I wear a bungee wing, an extra d-ring, put one stage on the right, dive deep air etc - so I am one of the people GI3 was talking about

just because they (your buddies) have never taken a chamber ride doesn't mean they haven't had symptoms and like yourself blown if off to some other cause

That thought had certainly occurred to me

Wow . . . if my buddies refused to adjust their deco profiles to help me avoid DCS, I'd really rethink diving with those buddies

Someone else doing additional deco isn't going to help me avoid DCS

There will be no issue about waiting until I've completed as much deco as I feel I need to; and no I'm not going to get bent just to save 5 minutes as I already said. But we don't team dive. If other divers finish their schedule before me, they will likely surface and wait for me there or on the boat. Yes I know that's no the way you guys do it

Having said that, I'm signed up for GUE-F with Gordon Liew through Tech Asia in Puerto Galera next month, so we'll see what happens from there