..but this confuses me a bit, so let me drill into it, in case I can learn something from the conversation. I always thought that whether a tissue is still on-gassing, or already off-gassing, depends only on the tissue, how saturated it is, and the depth, which is strictly a function of dive profile. It has been my understanding that algorithms differ in how far they allow you to go past that point where off-gassing begins, but that they agree on where that point lies. If my understanding is wrong, I'm glad I asked that question, so that I can clear this up.
Depending on the implementation of the algorithm, I'm fairly certain that they all somewhat vary in Half time, M and modifiers to those values thats used and I think for various tissues and that many manufacturers have slight variances in those and different modifiers on the algorithms and some are fixed gradient factors and some are adjusted, some take into account bubbles and some dont.. all of this affect ascent profiles.
Thats why you will never find 2 dive computers from different manufacturers match 100%... Some are heavily biased to pure Bühlmann models will chase you up shallow to spike gradient to maximize diffusion, some will stay longer deeper to account for bubble growth, some will stop at 70ft with 50 for longer than the shallow ones to maximize O2 window.. etc. etc. etc.
All this said, everything is based on what we "think" works best, there is no real way to figure out when off-gassing really starts in your body..its all theoretical..
GUE profiles are what we call "pragmatic" deco and was built and shaped based on empirical data from both thousands and thousands and thousands of dives between all our members overlayed what the various computer generated profiles seem to think works best AND whats practical and easy to apply, calculate, remember and perform during a dive.. we pretty much then create a linear ascent thats really very easy to remember and calculate.. And its like you said.. we ascent 30ft p/min to half max depth in ft, then stop 1min every 10ft to the surface... super easy.. and pretty much gaurentees that rule will fit into any recreational no-deco dive planned to 100ft on Nitrox32.. but you always only have to remember one ascent profile rule..
The golden key here is that this is a "standards" based ascent profile and dont matter what minor variance in dive profile or gas selection we each have, the entire TEAM will have the exact same deco schedule and ascent profile.. we favor the TEAM cohesiveness above all.. i.e. this leads to zero need for discussion and debate underwater between 3 divers making an ascent.. versus same 3 people diving 3 different dive computers thats all running different software and telling them different things... who is right? did the dive planning computer use the same profile that you based your gas planning on?? In GUE the entire team knows the EXACT ascent plan as soon as the dive is thumbed.. no surprises or debates on the way up.. the bottom phase and deco gas plan can be very very easily calculated in finite detail using such a standards based approach as well..
Will you shave off 3min here or add 2min there using a dive computer.. sure. probably.. or maybe not.. we just dont know.. so we choose to stick with the team and rather all be on the same page and keep things easy and simple
hope that makes sense.. If not.. it WILL make a lot of sense very soon..