I have the famous Apek's Quantum

[Woz]

Originally Posted by SoggyFox

DOTP?

Deco On The Pi$$??

BSAC Deco on the Pie.

http://www.yorkshire-divers.com/foru...archid=2287458

[JasonP]

Originally Posted by Woz

Or your buddy. You should only plan for one catastrophic failure. Otherwise you are over-redundant.

I don't always have one of them. I'd hardly call losing a buddy a catastrophic failure. And it's most likely to happen when you actually have a problem as you stop to sort something out, they don't notice and you lose contact with them right at the wrong time.

Jason

[BJ]

Sorry,

For the pedants out there, I should have said the EFFECTS of pressure changes are greatest towards the surface.

(I am sending this post off to be sub-edited so it might change next week.)

Edit: You are confusing me with someone who gives a damn!

[Lou]

Not sure I would call the loss of a buddy and a computer going dicky as two catastrophic failures.

I would class the likelihood of losing a buddy as a 3, and impact as a 3 if I do have a back-up and a 9 if I don't. Therefore, as a 27 risk, with an impact of 9 I should mitigate against it...by adding a back-up computer of my own

[Woz]

Originally Posted by JasonP

I don't always have one of them. I'd hardly call losing a buddy a catastrophic failure. And it's most likely to happen when you actually have a problem as you stop to sort something out, they don't notice and you lose contact with them right at the wrong time.

Jason

Losing your buddy isn't a catastrophic failure. However I reckon you should take 2 of everything that get's you back to the surface alive and well.

My point is that millions of recreational divers every year do dives with say 10 mins of deco on a single computer with no other backup apart from a buddy. Well maybe a depth gauge on a console dragging through the silt.

[JasonP]

Originally Posted by Woz

My point is that millions of recreational divers every year do dives with say 10 mins of deco on a single computer with no other backup apart from a buddy. Well maybe a depth gauge on a console dragging through the silt.

I'm not convinced it is millions of divers. A lot of PADI trained divers wouldn't contemplate doing any deco. And computers are generally pretty reliable, so there aren't going to be that many failures anyway.

Jason

[Jezza]

What ever happened to 'Plan the dive - Dive the plan'?

Surely people wouldn't be diving to 40m without having first planned their deco penalties, including allowing for the worst case (little deeper/little longer) scenario?

So you should know if your computer isn't calculating properly (for whatever reason)

Personally if i planning a dive requiring mandatory decompression, I would be using a a runtime slate (prepared with ProPlanner), 2 computers/timing devices, when in the water, I follow my runtime and decompress to the most conservative (wait until everything is clear).

Whatever dive I'm doing I always carry a set of air tables, I know these will get me out of the water (eventually).

As a rule of thumb if the depth plus the time is greater than 50 your into deco (on air).

Anyway back to the original question...

Using BSAC88 Tables - One of the least conservative!
Assuming you hadn't dived in the previous 16 hours and that you are diving at sea level

I don't know what gas you were diving so:

If 21% O2 (Air) - 39m for 24mins (time to first stop) = 3mins @ 6m
If 27% O2 (Nitrox) - 39m for 24mins (time to first stop) = 3mins @ 6m
(Yes they are the same).

So it would be unlikely that it was this that caused your problem (assuming the computer isn't faulty).

There is a blip around the 27min mark which wouldn't have made the computer too happy, however, I assume that you would have checked you computer after this and you would have noticed if it had given you any additional stops because of this (and you would have completed them!)

So it would point towards your final ascent (as previously mentioned on this thread) if you did go from 5m to the surface in 20secs as the graph would appear to indicate in red, then this is too fast and would appear to be the cause of your unhappy computer.

Back to basics for a minute:
1) At the end of your dive your body is saturated with nitrogen (and other gases if your diving trimix/heliox etc.) if this is above acceptable limits then you complete mandatory stops to allow this to come into tolerable limits. Therefore when you have completed your stops you are only just in the 'safe' zone.
2) Gas expands at it's greatest rate closest to the surface (remember boyles law)
so therefore the most dangerous place to have a rapid ascent is near the surface.
So add these 2 factors together and you get a very unhappy computer.

It amazes me when you see people fill their BC's at 6m and shoot themselves to the surface - Do they not think!

Anyway rant over.

[JasonP]

Originally Posted by Jezza

Surely people wouldn't be diving to 40m without having first planned their deco penalties, including allowing for the worst case (little deeper/little longer) scenario?

So you should know if your computer isn't calculating properly (for whatever reason)

Yeah, I do it all the time. I only bother to run a slate if I'm using trimix on stuff deeper than 40m. I know I'm going to get out with over half a twinset of gas, so that isn't an issue.

I use two computers with different algorithms and I'd know if they weren't calculating properly as I know roughly what they should be telling me. Plus I usually have a buddy and she's got a Vytec, so it always gives more stops than mine

Jason

[royplumber]

cheers for the postings very safe and helpfull