[tylerz]

First, I would suggest that the feelings prior to a blackout are the same as the feelings prior to a LMC/samba, however the mind often tends to be in a different state before each. A LMC/samba tends to happen when a diver has already determined they are ending their static or a dive happens to complete just shy of a severe O2 depletion. Blackout tends to happen more often when the diver is still focused on holding their breath, which tends to lend to more focus on what their sensations were until the last moments. So, further in my response here, any references to blackout also refer to LMC/samba. And if a person has had an LMC, then in my mind they have essentially had the experience of reaching blackout. During LMC one can completely lose consciousness without exhibiting a significant external loss of control such as we associate with blackout. And for this reason I see it as rather pointless to differentiate between them in the regard of assessing one's ability to control their dive to a safe range.

On an 8+ minute static, I have the urge to breathe half way, or less, through the static if I breathe up one way. If I breathe up another way I may have the urge to breathe 2/3 of the way through. I have never been able to get the urge to breathe to come later than 2/3 of the way, however, with enough modification to my diet and other modifications, I am certain it would be possible.

A dive is much more variable than a static however. Some dives have half of the dive spent more like a motionless static and half as continuous exercise, others are continuous exercise all throughout, some are on full inhale, others on less than full, some half sporatic motionless periods throughout the dive interwoven with exercise. Therefore a simple rule such as surface when you feel the urge to breathe, or surface before feeling the urge to breathe, is not very effective for a wide range of divers and diving styles, in my opinion. It also has the tendency of supporting peoples' inclination that they will feel the urge to surface on time, which for some people and for certain states of the body, can come in an unreasonably close proximity to blackout or not at all.

I believe that, unfortunately, if a person has not had a blackout/LMC then unless extremely experienced with numerous attempts at pushing their limits, they are unlikely to have solid grounds to comprehend for their body when they are close to blackout. The body can go through so many untoward feelings leading up to max apnea abilities, that one could determine all of them were the sign of the end, if they never see the pattern which actually arrives consistent with the experience of a blackout/LMC. These patterns may be person specific. I have not heard of a consistent and thorough explanation of a common feeling that people experience just prior to blackout. I believe part of the problem is people not wanting to admit they have had blackouts/LMC, which stops us from gathering the details of information related to it.

Hopefully this thread can gather more people's experiences, so, even those people who can't find a pattern, saying so is also a valid piece of information.

So, from myself, my blackouts/LMC's were precursored by a long time spent feeling "this is challenging already". During my two dive incidents, both times were spent in this feeling from the bottom all the way to the top, 45m and 61m. Nearing the end of the dives, I did not experiences a change in feeling other than more certainty that I was pushing the edge eventually degrading to lost memories and blurry memories with no feelings. My many dry statics ending in LMC, a dynamic, and a wet static, have been much the same, except another wet static while recovering from sickness just felt extremely brutal like trying to do a static after sprinting. From 3:00 to 6:00 I was pounded with CO2 headache, heat, and contractions. During all statics I feel my extremeties become heavy and buzzing long before the end. I have nothing I currently associate with "the end is nye".

Good thread, hope to see more data.