Stop Times and Run Times??

[Mark Chase]

Quote: (Originally Posted by lamont)

actually what i posted was a DOTF with pragmatic instead of s-curve stops (note that i haven't taken tech2 so i'm just relaying book learning, and there's notable errata in my source on other pages).



yep.

I am aware of the simplified stops system but I still prefer the S curve. Taking advantage of the 02 window and then maxing the gradient makes sense to me.

HOWEVER i grant its all voodoo and Pragmatic/ Simplified is probably more than adequate fro most dives. I am just working the "every little helps" principle of deco


ATB

Mark

[lamont]

Quote: (Originally Posted by Mark Chase)

As it is it just shows the big problem with ratio deco. for 20 at 72m its a very very soft deco but for 45 at 65 it's pretty damed aggressive. There is no set level of aggression with ratio deco. One dive its all cozy the next your balls are out in the wind. Pre planning is a must.

It is taught alongside ratio deco to use pre-planning. It is also taught as a tool so that if you plan a dive for 20 at 66m that you can compute a deco on the fly for 10,15, or 25 at 66m as contingencies, or +/- 3-6m. And the diver should still run all those profiles against decoplanner to confirm, and put the profiles in their wetnotes, and tweak and tune according to what works best.

45 at 65m is already 5 minutes outside the boundaries of where ratio deco is "advertised" to work, and I wouldn't follow a ratio deco profile at the limits unless I'd checked the profile in advance or there wasn't any other option. It is a crude approximation method based on noticing the relationships between certain numbers for certain profiles and certain gases. Its like approximating a parabola with a tangent line. The approximation is only going to be useful for a small delta around the point of the tangent. The tech1 1:1 setpoint, the tech2 2:1 setpoint and whatever they came up with on the brittanic dives are just different tangent line approximations to a continuous curve.

Quote:

I am aware of the simplified stops system but I still prefer the S curve. Taking advantage of the 02 window and then maxing the gradient makes sense to me.

HOWEVER i grant its all voodoo and Pragmatic/ Simplified is probably more than adequate fro most dives. I am just working the "every little helps" principle of deco

I was just trying to make it clear that the deco I posted was also a valid ratio deco example, but this is an example of tuning to what works best. Neither the pragmatic profile I posted or your profile with the more s-curve deco is more "right" unless you go out and actually dive the problem and one of them works better for you.

[Mark Chase]

Quote: (Originally Posted by lamont)

It is taught alongside ratio deco to use pre-planning. It is also taught as a tool so that if you plan a dive for 20 at 66m that you can compute a deco on the fly for 10,15, or 25 at 66m as contingencies, or +/- 3-6m. And the diver should still run all those profiles against decoplanner to confirm, and put the profiles in their wetnotes, and tweak and tune according to what works best.

45 at 65m is already 5 minutes outside the boundaries of where ratio deco is "advertised" to work, and I wouldn't follow a ratio deco profile at the limits unless I'd checked the profile in advance or there wasn't any other option. It is a crude approximation method based on noticing the relationships between certain numbers for certain profiles and certain gases. Its like approximating a parabola with a tangent line. The approximation is only going to be useful for a small delta around the point of the tangent. The tech1 1:1 setpoint, the tech2 2:1 setpoint and whatever they came up with on the brittanic dives are just different tangent line approximations to a continuous curve.


I was just trying to make it clear that the deco I posted was also a valid ratio deco example, but this is an example of tuning to what works best. Neither the pragmatic profile I posted or your profile with the more s-curve deco is more "right" unless you go out and actually dive the problem and one of them works better for you.

I understand the revised/simplified/pragmatic profiles and i don't have anything against them on the tech 1 arena. For bigger dives at Tech2 level i personally prefer the S curve concept. But i am open to what works works and i accept they are valid profiles in GUE terms.

As for the odd 5mins on the 45min profile, remember my Min's includes decent time. 65m is a 4min decent for me. From the profiles i have discussed with UK GUE divers doing 60-70m dives they are ignoring decent time and averaging depth on the shallow side. So to mimic their 40mins on the bottom I have to plan on 44-45mins.

ATB

Mark

[graham_hk]

Quote: (Originally Posted by Mark Chase)

Not acording to my book

1/2 Deco time on 02

1/2 Nitrox 50 time in 120'-80' range



This profile is already very soft and if what your saying is correct you going to add 25% to it??? It doesn't sound right.

As it is it just shows the big problem with ratio deco. for 20 at 72m its a very very soft deco but for 45 at 65 it's pretty damed aggressive. There is no set level of aggression with ratio deco. One dive its all cozy the next your balls are out in the wind. Pre planning is a must.

ATB

Mark

Sorry you confused me you said 50min between 21 and 6 - that means 50min at the 21, 18, 15, 21 and 9m stops then you said 25min at 6m. For your 20min profile you would do 25min between 21 and 6 and 25min at 6m. To add to the confusion you have posted nitrox 50 at 120-80ft above - nitrox 50 is used between 70ft and the surface (or 30ft if carrying O2)

Mark there is no problem with ratio deco - its fitting a straight line to a curve. If you don't like the standard procedure don't use it - but please stop wasting our time discussing it and posting pages and pages of profiles we can all generate (how can we argue with decoplanner stop times - you don't have to prove it by posting a screen capture).

At the edges ratio deco is going to be a less close approximation to the curve - this is known and accepted. If indeed you were doing dives outside the limits of the commonly spouted 1:1 and 2:1 ratios you need to find your own straight line. Your posts clearly show you don't understand this and therefore you are missing the boat.

GUE divers are taught to start with something known go out and dive alot and listen to your body - I know the 1:1 and 2:1 ratio works for me upto 50min bottom time and 15/55 - I don't see any reason to shave down the shallow stuff. You are asking clare and al to agree with you without even knowing what they did - you need to do the training they have done before you can understand what they are doing.

All the best, Graham

[rjack]

Is GUE still advocating 66m/220ft as the setpoint for 2:1 deco?? I know that this has been revised to 60m/200ft in AG's version.

[graham_hk]

Quote: (Originally Posted by rjack)

Is GUE still advocating 66m/220ft as the setpoint for 2:1 deco?? I know that this has been revised to 60m/200ft in AG's version.

GUE is not advocating any setpoint - you find your own on the course

[Mark Chase]

Quote: (Originally Posted by graham_hk)

Mark there is no problem with ratio deco - its fitting a straight line to a curve. If you don't like the standard procedure don't use it - but please stop wasting our time discussing it and posting pages and pages of profiles we can all generate (how can we argue with decoplanner stop times - you don't have to prove it by posting a screen capture).

All the best, Graham

Sorry Graham I must be odd but i like talking about this stuff and learning from others. I much prefer the use of profiles and charts depicting hard data combined with the empirical evidence of experienced divers rather than theory and rhetoric.

Why you find such an approach annoying on an open forum frankly baffles me. I like a laugh and a joke but mainly I log on to learn. Seeing as i use ratio deco myself and think its extremely useful (as a back up in my case) I don't know why you take offense at my attempts to better understand it by asking questions of the GUE divers who surely represent the largest group of divers using the system.

I am most iritating as i will usually refuse to blindly accept anything unless the information is cut and dried. That doesn't make me any less of an avid student.


ATB

Mark