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new CF for Stop Size?

Posted: 27 Jun 2011, 18:14
by PaC
Hi,

Please, would it be possible to add a CF to set the deco step spacing like V-planner software?

Something like...

CFxx: Stop Size

This value sets the distance between each decostop.
Recommended range: 3...5 (3m...5m)
default setting: 3

Thanks
Best Regards.

Re: new CF for Stop Size?

Posted: 27 Jun 2011, 20:24
by Beluga
As far as i know, is the distance between the stops only 3 meters in the buehlmann decompression model.
The other model - where you can set the distance - is the VPM model by Eric Baker.

Re: new CF for Stop Size?

Posted: 27 Jun 2011, 21:55
by Solodiver
So lets talk about implementing VPM then :-)

Re: new CF for Stop Size?

Posted: 27 Jun 2011, 22:07
by sailor
Hi,

i believe in that case you have to go for the DR5 and be ready to pay extra for the third party software.

Reiner

Re: new CF for Stop Size?

Posted: 28 Jun 2011, 10:02
by JeanDo
Hi,

Changing the step size in the Bühlmann implementation is easy. The good question is:
* Is it safe/wise/etc ? Buhlmann tables have been largely validated experimentally. Changing the conditions might impact safety margins.
* Does it go in the right direction ? The trend for Helium decompression is more to have the smoothest ascent. Doing larger steps (hence longer one) will indeed make the curve more jaggy.
* Is there any situation where it helps ?

Any advices ?

Re: new CF for Stop Size?

Posted: 28 Jun 2011, 11:12
by beuha
Hi,

i find the idea vey interesting, i give you some arguments in favor of the feature (from my point of view of course :) ):

- it is would be useful to match some runtime plan with 5m meter step.
- There is trimix deco table who uses 5 meter step, for example TSA.
- I believe 3m step have been choose arbitrarily because 3m is 10feet, and table are easer to use whith 10 value (only for imperial units users :) )
- Many people do their last stop in 5-6m, so A step of 5m is not a problem if it is correctly planned, fuhtermore the last stop is very critical due to most important pressure vatiation.

Regards,

JP

Re: new CF for Stop Size?

Posted: 29 Jun 2011, 07:37
by dmainou
Guys,

In my opinion, feature requests that modify the decompression algorithm should be supported with some piece of research.

A couple of weeks ago someone was asking for extra stops to those already generated by the algorithm with absolutely no basis to support their request other than its what they like to do.

Yes, things revolve around 10 ft for historical reasons but there is a ton of evidence supporting that model and that evidence suggests it works.

If you want to do 5m stops and ascent at 1m per min thats fine (simply set the GF to 100/100 do your tricks and closely screen the implied GF but I wouldn't suggest adding this as a feature until you have done a two or three thousand scientifically controlled and doppler supported dives.

To sum it up, if it ain't broken don't fix it.

D

Re: new CF for Stop Size?

Posted: 29 Jun 2011, 15:39
by PaC
Hi everyone.

I realized that the problem is more complex than expected. :(
The first idea was just to reduce the number of decostops to simplify the decoplan.
Now I agree that this option should be validated by scientific study.

As debate is opened, maybe VPM users could give us their feedback?

Perhaps this option may be available only in a simulator first or with a clear warning? ...

Regards,

Re: new CF for Stop Size?

Posted: 30 Jun 2011, 09:30
by JeanDo
Hello all,

Can someone point me to Helium decotables with a 6m step ?

Regards,