Question GF Low

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

In a general dive, you don't know if you'll not have a ceiling deeper than the current deepest ceiling.
You don't need to know ahead of time, you don't need to know individual tissue deepest ceilings, just the deepest of all of them. When a particular tissue current ceiling is deeper than the previous deepest ceiling, you update your deepest ceiling, otherwise you don't. Ceilings for all tissues are directly comparable to each other (even though tensions are not).

How will you compute updated ceilings without the max tissue tensions (which you threw away when you left the bottom before you saw the barracuda and stopped ascending / possibly descended)?
You don't need max tissue tensions to compute ceilings, only current tissue tensions are needed to calculate individual tissue ceilings. Even the deepest ceiling is only needed to anchor GF-Low. Max tissue tensions server no other function in the algorithm.

I suppose you could see where the current tensions intersect GFLow again, but that will typically give you deeper ceilings than had you kept the original max tensions.
If you are bellow your current deepest ceiling (GF-Low anchor), you need that deeper ceiling anyway to determine if it should be the new deepest ceiling. If you are above the current deepest ceiling, you will not generate a new deepest ceiling for any tissue.

You could use the previous per tissue max tension as a heuristic to reduce calculations on a per cycle basis, if you are throughput limited. But algorithmically, there is no need for per tissue max tensions.
 
You don't need max tissue tensions to compute ceilings, only current tissue tensions are needed to calculate individual tissue ceilings
This is the part you keep missing: without the max tension, the current tension AND a GF are needed to compute a ceiling (i.e., the intersection of the tension and GF lines). So what GF do you use? Again, this is a multi-level scenario where tension is lower than the max seen (thus GFLow is not appropriate as you're not resetting), but possibly higher than is acceptable at the "current" stop depth (thus the "current" GF from the assumed stair-step ascent is not appropriate).

Using the previous stop's GF (or the 2x, 3x, ... previous) is perhaps an option, but I'd submit the lack of granularity is undesirable when compared to just keeping the max tensions.

We've strayed rather far from the OP with discussion of these implementation choices. I'm happy to continue via DM if you'd like, but I think we're reaching the point of diminishing returns.
 
This is the part you keep missing: without the max tension, the current tension AND a GF are needed to compute a ceiling (i.e., the intersection of the tension and GF lines). So what GF do you use? Again, this is a multi-level scenario where tension is lower than the max seen (thus GFLow is not appropriate as you're not resetting), but possibly higher than is acceptable at the "current" stop depth (thus the "current" GF from the assumed stair-step ascent is not appropriate).
The GF for all tissues are either the GF for that depth given the GF-Low anchored by the current deepest ceiling which is a global not per tissue value, if not resetting. Or it is GF-Low if resetting.

The GF used at a particular depth is the same for all tissues at that depth, and is determined by linear interpolation to that depth from the all tissue deepest ceiling.


Using the previous stop's GF (or the 2x, 3x, ... previous) is perhaps an option, but I'd submit the lack of granularity is undesirable when compared to just keeping the max tensions.
Wouldn't you always use the GF for the next stop? Which would always be either GF-Low (if you are below the first stop), or one depth increment above your current stop.

We've strayed rather far from the OP with discussion of these implementation choices. I'm happy to continue via DM if you'd like, but I think we're reaching the point of diminishing returns.
You are probably right we should take it to DM.
 

Back
Top Bottom