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| Originally Posted by zaksherlock its a good job Im not on here to make friends. |
I don’t see any thing unfriendly in your reply Zac. It’s a balanced statement from the table’s camp. The article is my own work and therefore bias and I welcome comment and counter argument. It wasn't supposed to be definitive
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In recent years deco seems to have gone through a number of trends, from "first out of the water" (still prevalent) to "effective deco" (still relatively rare).
There is a lot of bollocks talked about the basis of deco theory, from gas gradient to bubble models. At the end of the day, find what works for you.. be comfortable with it... and be open to discussion/change.
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If I do a 50 -60m dive planned on 20/80GF with the VR3 set to 0 safety and actually stick exactly to plan I will only save a couple of mins with the computer tables over the VR3. This demonstrates that the VR3 algorithm is fairly conservative. However on my first ever dive on the Duke all I knew was that it was a 60m wreck. So I planned for 30mins at 60 with the usual +/-5, 10 15min bailouts. Andrew my dive buddy was on the same gas and same 2-deco mix as I. Having dropped onto the wreck we did the whole dive between 50 and 55m. in the cargo holds. We left the bottom on 30mins as planned and Andrew had 50mins of deco to do on his tables. I had 36mins showing on the VR3.
Andrew was so pissed off he went out and got one the following week.
That had nothing to do with a desire to get out of the water fast it was purely down to the dive not matching the plan. Comparing tables against the computer over all dives since the picture has stayed the same. However on our 100m dives in the red sea the opposite happened. Our first deco stop planned on deco planner was at about 66m. The VR3 surprised us with an 80m first stop. When we got back and analysed the dive our drop to 102m and a forced delay at 90m would have asked for a stop at 75m on deco planner. On that occasion the VR3 added deco for all the right reasons.
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This business of "computers deco you faster" is probably true. Having said that, I don’t give a flying f*ck about speed of deco, what concerns me is how I feel after the dive (thermal/deco considerations). A damn good mate of mine (who happens to be an excellent diver), regularly exits the water 10-20 minutes before me on dives in the 60-80m range. Fair play to him... good luck.. he gets to bag the first biccies..... but frankly... how much difference is a few minutes??
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I couldn’t agree more
Andrew and I add a 3m/min - 5m/min ascent from the deepest stop to the deco recommendations of the VR3 and regularly insert stops where we feel that the jump recommended on the VR3 is too big. We then clear the VR3 on the 6m stop and spend a further 5mins getting up the last 6m and out of the water. I then prefer to continue breathing 80% 02 on the surface and back on to the boat. Having sat down I will still breathe 80% until de kitted and totally relaxed. This adds surface waiting time (variable) and a minimum 5mins on the boat to the time spent breathing 80%.
As an old fat git I am in no hurry to do most things including deco. However in the light of my experiences with tables in the past I still prefer to use computers to monitor and calculate the dive. I had hoped the article I wrote expands on a range of issues rather than just keeping deco to a minimum.
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I spoke to a chap tonight about dives in the 140-160m range, who merges VPM-B and Buhlmann. I laughed.... again.. he's doing what works.
So what’s my point? Deco is an inexact science...... don't push it... enjoy your diving and keep diving for many years.
Don't be fooled by glittery toys/deco models... they only represent peoples desire to model what’s *really* happening. Do what 'feels' good. At the end of the day.. keep reading.. keep learning... keep an open mind.
/Zak
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What works works is a statement very well suited to deco theory. Unfortunately to find out what works you have to push the limits. I probably would have been well up for that aged 20 but aged 40 I want to avoid limits like the plague. I hope I was clear when I said no computer model or pre cut table could replace proper dive preparation and understanding of basic decompression theory. If I wasn’t then please read this and note it down because it’s very important.
Computer models, dive computers and PC decompression programs are tools. They can be used by skilled people to craft good clean profiles. Semi skilled people can create workhorse models that usually work and unskilled people can create total f#ck ups. Most of the time the unskilled person will get away with it and you can guarantee when it bites him he will blame his tools.
ATB
Mark Chase