Choose Your Poison - Part 2 - Nitrox

[@josephfarabee8786]

Harry, you are a phenomenal teacher. I just finished up a Nitrox class where we learned how to plan our Nitrox dives on our computers but learned very little about the theory behind the calculations. You’ve opened up a new world to me! Super excited about learning more, and taking my diving knowledge and skills to the next level. I’m loving the process. Being from Florida I’m super excited to get on my way to cave diving training. You’re a hero!

[@DrHarryH]

Thanks Joseph. Hope you are ok after the hurricane!

[@josephfarabee8786]

@@DrHarryH Wow thanks for considering us here in Florida. I am doing just fine. My church and I are tirelessly working to deliver essential resources to the area that took the brunt of the storm. I’m located in Venice. The worst is just south of me. Everyone is in a pure state of generosity and this community is really pulling together right now.

[@RunstenRacing]

Thanks for a bunch of really informative and interesting videos. I'm just a recreational diver but it's real good to know and understand the science behind the rules we're adhering to when diving. I've been watching quite a few of your videos the last few days and they're awesome! Keep up the good work!

[@adammarston1891]

Thanks for taking the time to put these together, all your vids are awesome 👍👌

[@DrHarryH]

Thanks for the feedback, trying to get better!

[@lolonav]

I'm just owi teaching about blending on partial pressure and i give a link to this very usefull vidéo to the student thank you !

[@gnampfelpamp]

Stumbled across the channel with the 245m dive. Loved the commentary there! But I subscribed for these informational videos. I really enjoy both types of content, looking forward to more. Got me hooked on technical diving already!

[@gnampfelpamp]

PS: I'd be very interested in you walking us through a dive, where you change gas, to which you change, etc.

[@DrHarryH]

Thanks for the comments. I can talk about gas changes in the upcoming trimix talks. Of course with rebreather diving we don't tend to change gases because the machine does all the work.

[@TheGiuiba]

Thank you for this extremely clear explanation. I'll recommend this resource to my peers.

[@GMartins222]

Great video, perfect length and a lot more helpful than many other guides like these you'd find online. Thanks, looking forward to the next one!

[@DrHarryH]

Thanks for that!

[@dannychampion5710]

I must admit you are brilliant at ur job guys great videos will be telling my friends about ur channel they will love it too good luck guys

[@benediktbohm6419]

Great video! Looking forward to the next one!

[@JURASSICCOASTMODELLER]

Again... another excellent informative video!

[@jimdarby967]

Thanks!

[@markusleitner3735]

Thank you very much for putting together the data and doing the video, that is just super! I like all your content! Keep it up!

[@padraicmcgraw]

Thanks for the vid! Just all around a great video.

[@mikhailfilitov1479]

A really good video but I wanted to especially thank you for discussing your 'no-evidence' study. I know there are significant pressures (and biases) pushing for positive findings and a desire by journals to publish the more 'exciting' positive results and it's a very, very positive sign of your credibility/professionalism that you're happy to cite negative results, let alone results that you were involved in.

[@952way]

Great series! Looking forward to the trimix video :)

[@H_E_N_X]

Awesome, I was looking forward to the next episode. I hope you do more videos like these because they're so fascinating. 👌‍

[@brois841]

@4:20 I really don't like fooling around with the computer and giving it different gasses than you're actually diving. I'd recommend people just buy a Shearwater (or another good computer with gradient factors) and set their GF to a more conservative value (decreasing the GF-high).

[@DrHarryH]

In general I would agree about intentionally entering a 'wrong' gas. However in this case by using an appropriate nitrox for the depth you are diving and setting the computer to AIR (assuming no decompression limit diving), you will add a good degree of conservatism to the dive profile. Adjusting gradient factors on your computer in shallow water (

[@brois841]

@@DrHarryH well, you mentioned the risk yourself @12:01 whereas if you set up your computer properly it'll warn you when PPO2 is being exceeded. You won't get that warning if the computer is set to air. The best way to add conservatism is to reduce the GFhigh value. I just ran some numbers on my Perdix. Using EAN36 with a low conservatism (GFhigh of 95) NDL time at 90 ft (almost 30m) is 42 minutes. With high conservatism (GFhigh of 75) NDL time at 90ft is 27 minutes. That's a pretty significant change in bottom time. If we want to turn it up even higher, I set up a custom GFhigh of 60 and now my NDL at 90ft is only 18 minutes. I agree most divers don't understand gradient factors, so they should just set the conservatism to "high" on their computer and call it a day, not hack the mixture.... just my opinion of course. Thanks for taking the time to respond. Love your videos! :)

[@meridacavediver]

Great video Richard. I’m always in deco so I almost never think about it but if I was a new diver, I might wonder… why am I trying to avoid NDL? What’s the big deal?

[@DrHarryH]

I guess you mean, why would anyone worry about going into deco these days? I think as experienced divers we forget that having compulsory deco adds a number of potential problems that can easily catch out the untrained or under prepared diver. Inadequate gas supply, an increased risk of decompression sickness, buddy separation, changing surface conditions and many more. Training in deco diving makes sure that the diver has at least considered all the extra possible hazards.

[@meridacavediver]

@@DrHarryH ah, yeah I could have worded that better but great answer.

[@alexfinn7989]

Such great information. Thank you.

[@DrHarryH]

Glad it was helpful!

[@DarkSideDiving]

Thanky you. Amazing video yet again.

[@davidMax78]

Great video as always ! Thank you 👍👌

[@matthewwyjad]

Another advantage to nitrox at the deeper end of recreational diving limits that I don't know if I missed you mentioning or not, is that of decreased narcosis effect. Or am i wildly misinformed about that?

[@DrHarryH]

Interesting point. Because there is a theoretical possibility that oxygen is also narcotic, we don't tend to count on decreased narcosis. Also, at the depths where narcosis becomes a big issue (say 40m), the oxygen percentage is down to 28% or less so the possible advantage is lost.

[@matthewwyjad]

@@DrHarryH yes. Perhaps the advantage is minimal within rec limits. I don't have enough deep nitrox experience to even offer anecdotal evidence on the matter. difference. I just noticed you hadn't mentioned it and it got me thinking.

[@lolonav]

Yep the o2 is more dense than n2 so could be more narcotic curious about research on that but for sure the gaz density is increase so the capacity to do effort is reduce .

[@Mrveescuba]

👍👌

[@kaznoiri]

Hi Harry, thanks for the amazing video. I truly loved it! While watching the video, I came up with a question. Which would it be more effective, and what are the physiological difference to the body between: A. Diving with the best mix EAN for the whole time vs B. Diving with air then off gassing with Deco on the way up? Many thanks in advance!

[@DrHarryH]

Simpler to dive with the correct nitrox the whole dive and ascend within your no-decompression limit (NDL). And you will get a longer bottom time using nitrox compared with air.

[@kaznoiri]

@@DrHarryH thank you very much for your reply! What I noticed while planning and comparing deco dives with Best Mix EAN vs Air + 80% EAN was, the better weapon (better poison in this context? :)) flips from around 30m/60min dive and onwards.. So would you say, high EAN mix benefits more for deeper/longer dives comparing to the Best Mix EAN? I'm guessing this is due to the effectiveness of off-gassing with high EAN mix overtakes the benefit of Best Mix EAN's reduced nitrogen loading at certain point... Apologies if my question doesn’t make sense but I've always wondered about this and never got a clear answer to this burning question 😂

[@lolonav]

Best is to do both the highest mix for the depth (up to 35 /40m max) and then 100% for deco (simple to blend) or multiple mix 50% and 100%. There is maybe a point to dive on air if exercise is needed at depth to reduce gaz density but if this is behond 35m maybe helium should be considered . I don't know if this help but I've try ...😊

[@kaznoiri]

@@lolonav awesome thank you so much for the info! Really appreciated your reply:)

[@williamsweet7511]

what do you think about the ANDI safe air and their air training program, is it a sales pitch or an actual thing. they claim to be the best gas program

[@DrHarryH]

I don't really get it. I don't see a need for a bridging course between air diving and nitrox. But I readily admit I don't know the details of what they teach.

[@martinsachs3837]

Recreationsal diver with poor buoyancy control in 50m of water. Thats all it takes to die on nitrox.