I wish there was more information about the Doppler bubble detector and the results and the rationalization for why he has decided not to breathe oxygen after each dive. There are reasons not breathe O2 while freediving. I'd like to hear their reasoning, though.
It would seem that Patrick is confident that his rapid dive speed will keep him out of harms way for DCS. And it looks like he is respecting the possibility of mirco bubbles by taking two days off after the 150m dive. Hopefully, that is enough, who knows for sure?
If his 200m dive would be completed in around 3'30" then we can make an interesting comparison with a 100m constant weight dive.
In constant weight, the dive time is around or over 3'30", exertion is high on the ascent, the descent is quite slow (sinking velocity at around 1.0m/s), the diver may or may not be cold, and may or may not have made any warm up dives.
In a no-limits dive, the dive time is around 3'30", extertion is minimal on the ascent and descent, the descent is fast, and the ascent very fast, and I would image that in Egypt, Patrick would be warm, since he doesn't need to limit the thickness of his neoprene as he would in constant weight. From the profile, it doesn't look like he slows down at all in the last 20m.
What's interesting is that in both dives, the diver spends an equal amount of time below 20m, beyond which microbubbles would be accumulated. The difference is that in the 200m case, the pressure is doubled vs. 100m, but the diver does not exert himself. I guess the question that needs to be answered is: which factors are most important in contributing to DCS? Pressure, dive time, exertion, physiological state, temperature, etc... ?
For example:
100m constant weight diver = 3'00" below 20m to 10 atm with exertion + 30 seconds above 20m.
200m no limits diver = 3'00" below 20m to 20 atm without exertion + 30 seconds above 20m
Also, I don't know how to express this in numbers, but it seems to me that proportionally, the constant weight diver spends more time in the danger zone for DCS relative to the depth. If the constant weight diver did a 200m constant weight dive, this would become immediately apparent, with a dive time of almost seven minutes!
If a constant weight diver at 100m is likely on the edge of DCS, I would assume that a no limits diver who can do 100m in 1'45" would have a much lower risk of DCS.
Anybody else have ideas on how to break this down to explain what Patrick is doing?
I still wonder how his chest will handle 20 atm of pressure....
It does sound like Patrick has worked out an interesting plan to make the depth.