Thanks for watching! 🔔SUBSCRIBE ➜ bit.ly/SBRUclips⛵ Informative Sailing Videos! Click here for more info about the SeeAir ➜ cutt.ly/seeair What are your thoughts on this? Comment below! God bless, Chris, Rossella & Emma :-)
What a shame that this channel has not uploaded for some time now. Chris has an amazing way of providing such helpful advice. Advice that I have used on my onwn boat. This channel could have absolutely blown up to hundreds of thousands of subs (still can) I wish Chris, Rosella and Emma all the very best and hope to see you back on the channel one day soon.
Thank you very much for the compliment, you'll be pleased to hear that we have more videos coming and, God willing, we'll be going on our adventure to the Med via the inland waterways this summer. 🙏 Best regards, Chris, Rossella & Emma
Thank you! We're all good thanks - more videos are coming soon and (God willing) our inland waterways adventure to the Med will be underway this summer. 🙏 Best regards, Chris, Rossella & Emma
It's probably very doable. Providing they supply 11bar pressure to the second stage mouthpiece at 10-12m with the volume of the quoted 56l/min then it should work. If the batteries or pump fail then it's unlikely that you would lose instant breathing but you would notice (very quickly 1-2 breaths at most) a sudden drop in flow. (I've had it happen at over 150m). There's always residual pressure in the hose and system before total loss.. If they have designed this well then I would hazard a guess there would be a small buffer tank in the surface unit. If you're splashing around under a boat this would probably work fine, if you think you will use it diving around at 10m as a replacement for scuba cylinders then don't buy one because it's risky. The most dangerous part of all diving is the first 10m because of the doubling of pressure and halving of volume. It's a misnomer to think 'oh, it's only ten metres' .....no that is the range where you can get decompression sickness etc . So these units are fine for boat cleaning or splashing around in the shallows with plenty of visibility and calm weather. And that is their limits. Anything more then dive properly with the right training and equipment.
within 20m you don't get decompression sickness you can get lung damages due to barotrauma if you don't breathe out. In fact decompression stops aren't required. PADI schools train to do it anyway. Within the 20m you are always inside the safety curve. You can rise up from 20m with just your last breath with an exhaling ascent without any damage. (especially if the maximum depth is 12m) just don't hold your breath and calmly rise up slowly exhaling air
@@ame2deo I would have to disagree, decompression sickness as you already know is gas bubbles being trapped and often bubbles joining to form a larger bubble then being trapped in the central nervous system. So it would depend on the level of Saturation of the bloodstream and then how rapid a release? So as the average scuba diver is not likely to get to a saturation level it would be rare, but I would say it is certainly possible to get decompression sickness sub 20m if saturated and theoretically even if not saturated, but probably rare.
I have enjoyed your videos! I am the 68 year old version of you. I have done the same with automobiles -- my line of work, collision repair -- to homes and now, I am going to retire in a warmer place with a sail boat! I am thinking Phillipines with a Colvic Rover! I am also lured by the Choi Lee 38, but a dollar is a dollar afterall. I can't resist the idea of being able to beach at will with Colvic's tri-keel design. A VERY economical boat would allow me to also rent a condo should I end up in the Phillipines. What I won't do is lose a bunch of money, like you in a way. As I just might live to be 100 years old, I am not willing to sell the ranch to finance my desire. I have to do it on the cheap! Now that I have found your videos in my research, I will be watching them all for sure. Good Show, Philip Spoutz Harsens Island Michigan USA
Hi Philip, I like your plan, except I think you should be aiming to live to 125! If you haven't bought a boat yet I have some training to help you buy it at the best price possible. Access to the beginning of the course is free, then there is the option of a paid upgrade if you want the rest. Let me know if you want a link. Best regards, Chris 👍
As an experienced diver, my only concern would be the use by people with no formal scuba training. As those with any scuba training are aware, the greatest pressure changes occur in the first few meters, the very depths this equipment is designed for. A person with only snorkeling or free diving experience may not be prepared for the rapid expansion of air in the lungs if they were to hold their breath on surfacing and the real danger of lung injury that poses.
You can make an emergency exit from water starting at 20m with just the last breath you had. When rising the air expand in your lungs and doesn't make you feel like you are breathless. In fact you have NOT to hold your breath but rising calmly and breathing out slowly. Let's say at the rate of the bubbles going up with you, This tecnique let's you get out safely from yhe water even without air in the tank and no safety stop has to be done (unless you went deeper than 20m but this is not the case). So the best is to train going 12m below, take your last regular breath, take out the regulator holding it in your hand and rise up calmly at a slowly pace following the bubbles and gently letting the air getting out from your lungs. Once you have learnt the "last breath due to technical fault" isn't a problem anymore.
Hello Chris, I have a simple question. I saw some videos of you working on a Volvopenta Marine engine - serie 2003. I have the same engine in my sailboat. Unfortunately, the exhaust riser (840891) on the exhaust is defective. Unfortunately, volvopenta no longer manufactures spare parts. do you know a company that manufactures such parts or sells functional used parts? it would be nice if you could help me werner from southern germany
Hi Werner, you could try here: www.volvopenta.com/shop/523388/part-sections/54143643 Alternatively, I've seen people with aftermarket stainless steel exhaust elbows, so you might want to look them up too. Happy fixing! Chris
We used a very similar one just the other week to do some work on our test rig for work, to avoid using 'proper' scuba gear. It works great! though as mentioned, you dont want to be exerting yourself that much. Tangling isnt an issue.
Welcome back Chris, we've been missing You. Hope everything is fine with You and your loved ones. Yep, I agree it's a handy device to have onboard. But I'd stay behind and watch if this technology proves itself. And until it happens, I'm using my trusted wet suite, diving weights and a snorkel with a mask. Also this season I'm thinking of trying one of those window installers' vacuum suckers to stick myself to the hull while I'm scrubbing it Anyway, fair winds, following seas and calm anchorages for You Sir
Hi Chris. As you say potential dangers. Your spot on 2-3 Mtrs no deeper. Good idea but there is a much cheaper way to do the same thing. Take a look at our how to build a cheap hookah video. Hope you and the family are doing well. Looking forward to you sailing down to the Med. Sail Safe mate. Ant & Cid
Ran sailing has a similar product, and they use it for cleaning the hull under water. less space needed than tanks and a compressor and probably cheaper. The risk with kickstarts, is they may fail to deliver and you end up out of pocket
@@SailingBritaly We are, though with less sailing than we'd like but hope this summer brings us time and fair[ish] winds - and still unrepentantly ''non-compliant'' in our old age. You are missed x
I'm sure I've seen other, similar products before. Just not sure of the right search terms. I think the idea is that you're always in a situation where you can just bail out to the surface. I'd be concerned about tangles, not so much as a risk to life but it's a lot of money to leave bobbing about over a reef or whatever. Could be handy fo cleaning the boat but then you have to untangle it from your prop and anchor before you can leave.
i will buy a atemregler for 26E and let my oelfree compressor running . the compressor has cost me 120 something Euro, makes up to only 4bar. think for diving on the hull it will be enough
While this product looks interesting, I see several issues. (1) The battery is not replaceable. This suggests the product is designed to be thrown away rather than repaired when an issue occurs. (2) On the main page, no members of the product team are identified for their familiarity with the design and safety of diving systems. (3) The "one size fits all" dive suit?? I'm not aware of any material that would allow one to make such a thing. When I looked at the Q&A, several people asked about this, but the answers were in a "don't worry, trust us" tone. Their response to this has me wondering how up-front they are about other issues. There is a similar product with replaceable batteries but a fair bit more expensive going by the brand "Blu3" - but it seems they have had some recall issues recently.
I would be very skeptical that this will end up being produced. I own three Nemos and one nomad and I can tell you by visiting the factory. It requires a lot of engineering to get a good system. The systems I have are very good and I don’t see how you could produce a decent system for 300 bucks.
There is a lot of thought and attention to detail which has to go into this for sure. They aimed to raise $20k and have instead raised $500k, so they have some decent funds to work with! God bless, Chris
@@SailingBritaly I hope they get it produced, I will be a definite buyer of multiple units but I will have to wait until they have a proven track record before I can put divers down with them. PS I I have really enjoyed your videos over the years.
from what i remember about all those dive courses is that compressed air is, could i say, the "first" cause of problems. if the air isnt compressed but merely pumped, you can hold onto to it upon ascending because you wont blow your lungs. bottom time is a relation from the amount of nitrogen intake which varies for each depth (oxygen also has its thing by providing toxicity after 66 meters, due to its partial pressure within what we call "air", but one can train for this - im not advising that!-) so i wouldnt remember if 5 hours exceeds the bottom time for 12 metres deep. i can be mixing stuff that ive learn a long time ago so take all of this lightly.
the problem is caused by the fact the air is compressed by the depth and not in the bottle. when you breath from the regulator the air is not under the pressure of the bottle (or it will kick your brain out) but just "concentrated" by the depth. The problem arise when the bubbles expand in your blood before your body tissues can absorbe it.
@@ame2deo thats decompression sickness, "the bends", thats a different subject which relates.to.speed of ascent and the elimination,.thru.breathing, of the absorbed gasses in the blood stream. what you also refer to as concentrated is the reason why the deeper you.go the faster you will.consume the.volume of gas inside the.tank, ie, you.still.need a definite.volume.of gas to.sustain life but said.volume will be filled with a bigger amount of gas because the latter is.being.further.compressed by the surrounding pressure of water(depth). breathing pumped air isnt the same as breathing compressed air
@@pmnfernando nope. 1L of air in your lungs compresses while descending. so as you are breathing the same amount of liters you are taking in n-times the air you wouls have had on land. this means your blodd has higher concentraion of gasses. So as your body keep on absobing gasses at the same rate you have to give time to your body to absorb that extra gasses that are oversaturating your blood. if you don't do it that extra gas in your blood expand while climbing and so the decompression sickness arise. Unless you are usin a trimix the air compressed in the bottle is ambient air..this is why it's crucial to fill the tanks with the cleanest air possible (therefore away from exhaust gas)
@@ame2deo i thin k we are talking in circles. you just repetead what ive said, wording it in a different way. i will refer to your first initial answer when you mentioned: "when you breath from the regulator the air is not under the pressure of the bottle". what is happening is: the regulator 1st stage reduces 90% of said pressure and the remaining 10% are regulated by the diaphragm which also makes the air available "on demand" ie, when you need to inhale. the air you are breathing is still compressed air from the tank plus being compressed, still inside the tank at the depth you currently are. this is the reason why, whenever we, for some reason loose the mouth piece regulator, are trained to continually exhale a stream of bubbles. why? because if you do inadvertently start to ascend , the exhalation will prevent the expansion of the gas inside the lungs thus avoiding a pneumothorax, or the beginning of it in the form of burst alveoli and tiny cappilary vessels. trimix is a blend using helium because this gas is less narcotic that nitrogen, thats the reason why it is incorporated into the blend, thus decreasing the quantities of oxygen and nitrogen present. being less narcotic has a better effect in ones CNS. Trimix is used to for tecnical deep diving, in conjunction with nitrox , air, and even 100% oxigen for some of the decompression stages, which will take hours!.
If the first stage decompress 90% and the second stage decompress the other 10% it sums up at 100% the air you breath when inhaling is at the pressure of the depth you are. Sending down from sea level or breathing through a bottle is more or less the same air. You said the air in the bottle is different from the regular air which is not unless is a mix. Nitrox or trimix. The problem arise when the absolute quantity of Nithrogen due to the compressed air by DEPTH, arise over certain level. Because your body can absorb just a small quantity. Because the difference between what you inhale and breath out stays in your body. Being Nitro 79% of the air, being you can absorb small quantities (while of oxhygen you absorb way more) it stays in your bloods for a longer time. This is why already at 20-30m you suffer from narcosis as your body is already at higher level of absorption of Nitro. So. No the air you breath is compressed by depth. If a had regular dive within 20m your body is capable of absorb the nithrogen. Beyond that the concentration is too high and you have got wait your body to absorb enough to get its level to a safety threshold. By the way at 12m you can dive not incurring in any problem other than lung damages due to holding your breath when rising up
Thanks for watching! 🔔SUBSCRIBE ➜ bit.ly/SBRUclips⛵ Informative Sailing Videos!
Click here for more info about the SeeAir ➜ cutt.ly/seeair
What are your thoughts on this? Comment below!
God bless,
Chris, Rossella & Emma :-)
What a shame that this channel has not uploaded for some time now. Chris has an amazing way of providing such helpful advice. Advice that I have used on my onwn boat. This channel could have absolutely blown up to hundreds of thousands of subs (still can) I wish Chris, Rosella and Emma all the very best and hope to see you back on the channel one day soon.
Thank you very much for the compliment, you'll be pleased to hear that we have more videos coming and, God willing, we'll be going on our adventure to the Med via the inland waterways this summer. 🙏 Best regards, Chris, Rossella & Emma
@@SailingBritaly Fantastic. Looking forward to it!!
happy new year Chris; like many I miss your videos, when you get a chance drop a short one to tell us all is cool for you and your beautiful familly !
Thank you! We're all good thanks - more videos are coming soon and (God willing) our inland waterways adventure to the Med will be underway this summer. 🙏 Best regards, Chris, Rossella & Emma
@@SailingBritaly Good to hear all is cool for you, Rosella and Emma and that you are coming back on YT!
It's probably very doable. Providing they supply 11bar pressure to the second stage mouthpiece at 10-12m with the volume of the quoted 56l/min then it should work. If the batteries or pump fail then it's unlikely that you would lose instant breathing but you would notice (very quickly 1-2 breaths at most) a sudden drop in flow. (I've had it happen at over 150m).
There's always residual pressure in the hose and system before total loss..
If they have designed this well then I would hazard a guess there would be a small buffer tank in the surface unit.
If you're splashing around under a boat this would probably work fine, if you think you will use it diving around at 10m as a replacement for scuba cylinders then don't buy one because it's risky.
The most dangerous part of all diving is the first 10m because of the doubling of pressure and halving of volume. It's a misnomer to think 'oh, it's only ten metres' .....no that is the range where you can get decompression sickness etc .
So these units are fine for boat cleaning or splashing around in the shallows with plenty of visibility and calm weather. And that is their limits. Anything more then dive properly with the right training and equipment.
within 20m you don't get decompression sickness you can get lung damages due to barotrauma if you don't breathe out. In fact decompression stops aren't required. PADI schools train to do it anyway. Within the 20m you are always inside the safety curve. You can rise up from 20m with just your last breath with an exhaling ascent without any damage. (especially if the maximum depth is 12m) just don't hold your breath and calmly rise up slowly exhaling air
@@ame2deo I would have to disagree, decompression sickness as you already know is gas bubbles being trapped and often bubbles joining to form a larger bubble then being trapped in the central nervous system. So it would depend on the level of Saturation of the bloodstream and then how rapid a release?
So as the average scuba diver is not likely to get to a saturation level it would be rare, but I would say it is certainly possible to get decompression sickness sub 20m if saturated and theoretically even if not saturated, but probably rare.
I have enjoyed your videos! I am the 68 year old version of you. I have done the same with automobiles -- my line of work, collision repair -- to homes and now, I am going to retire in a warmer place with a sail boat! I am thinking Phillipines with a Colvic Rover! I am also lured by the Choi Lee 38, but a dollar is a dollar afterall. I can't resist the idea of being able to beach at will with Colvic's tri-keel design. A VERY economical boat would allow me to also rent a condo should I end up in the Phillipines. What I won't do is lose a bunch of money, like you in a way. As I just might live to be 100 years old, I am not willing to sell the ranch to finance my desire. I have to do it on the cheap! Now that I have found your videos in my research, I will be watching them all for sure. Good Show, Philip Spoutz Harsens Island Michigan USA
Hi Philip, I like your plan, except I think you should be aiming to live to 125! If you haven't bought a boat yet I have some training to help you buy it at the best price possible. Access to the beginning of the course is free, then there is the option of a paid upgrade if you want the rest. Let me know if you want a link. Best regards, Chris 👍
Hi Chris. Glad to see you're still around. John
More vids inbound John! 👍
As an experienced diver, my only concern would be the use by people with no formal scuba training. As those with any scuba training are aware, the greatest pressure changes occur in the first few meters, the very depths this equipment is designed for. A person with only snorkeling or free diving experience may not be prepared for the rapid expansion of air in the lungs if they were to hold their breath on surfacing and the real danger of lung injury that poses.
hey Chris! what's up with you? yours vids were absolutely great and you have the most lovely brito-italo family in the world!
🙏We've got more videos coming soon! Chris 👍
Interesting...It is good to have you back Chris 👍
🙏👍
You can make an emergency exit from water starting at 20m with just the last breath you had. When rising the air expand in your lungs and doesn't make you feel like you are breathless. In fact you have NOT to hold your breath but rising calmly and breathing out slowly. Let's say at the rate of the bubbles going up with you, This tecnique let's you get out safely from yhe water even without air in the tank and no safety stop has to be done (unless you went deeper than 20m but this is not the case). So the best is to train going 12m below, take your last regular breath, take out the regulator holding it in your hand and rise up calmly at a slowly pace following the bubbles and gently letting the air getting out from your lungs. Once you have learnt the "last breath due to technical fault" isn't a problem anymore.
Hello Chris,
I have a simple question.
I saw some videos of you working on a Volvopenta Marine engine - serie 2003.
I have the same engine in my sailboat.
Unfortunately, the exhaust riser (840891) on the exhaust is defective.
Unfortunately, volvopenta no longer manufactures spare parts.
do you know a company that manufactures such parts or sells functional used parts?
it would be nice if you could help me
werner from southern germany
Hi Werner, you could try here: www.volvopenta.com/shop/523388/part-sections/54143643 Alternatively, I've seen people with aftermarket stainless steel exhaust elbows, so you might want to look them up too. Happy fixing! Chris
@@SailingBritaly Hello Chris,
Many thanks for your quick reply and for your good advice.
happy sailing
Werner
We used a very similar one just the other week to do some work on our test rig for work, to avoid using 'proper' scuba gear. It works great! though as mentioned, you dont want to be exerting yourself that much.
Tangling isnt an issue.
👍👍
Welcome back Chris, we've been missing You. Hope everything is fine with You and your loved ones.
Yep, I agree it's a handy device to have onboard. But I'd stay behind and watch if this technology proves itself. And until it happens, I'm using my trusted wet suite, diving weights and a snorkel with a mask. Also this season I'm thinking of trying one of those window installers' vacuum suckers to stick myself to the hull while I'm scrubbing it
Anyway, fair winds, following seas and calm anchorages for You Sir
🙏👍
What has happened to Sailing Britaly with Chris, Rosella and Emma? Loved the informative videos, but haven’t seen anything for months!
Hi Chris. As you say potential dangers. Your spot on 2-3 Mtrs no deeper. Good idea but there is a much cheaper way to do the same thing. Take a look at our how to build a cheap hookah video.
Hope you and the family are doing well. Looking forward to you sailing down to the Med. Sail Safe mate. Ant & Cid
Ran sailing has a similar product, and they use it for cleaning the hull under water. less space needed than tanks and a compressor and probably cheaper. The risk with kickstarts, is they may fail to deliver and you end up out of pocket
I've seen a Pelli case version with the integrated compressor which is run from the boat, rather than floating. Can't remember which one RAN uses.
Hello Chris, long time. Thanks for sharing it
👍
Thank you - this is interesting. I appreciate you taking the time to mention it.
🙏
@@SailingBritaly I hope all is well with you in this insane world.
All good thank you Fionna, praise the Lord! We hope you and yours are well too. 🙏
@@SailingBritaly We are, though with less sailing than we'd like but hope this summer brings us time and fair[ish] winds - and still unrepentantly ''non-compliant'' in our old age. You are missed x
Nobody has ever complied their way out of tyranny... God bless you and your family. 🙏
I'm sure I've seen other, similar products before. Just not sure of the right search terms. I think the idea is that you're always in a situation where you can just bail out to the surface.
I'd be concerned about tangles, not so much as a risk to life but it's a lot of money to leave bobbing about over a reef or whatever. Could be handy fo cleaning the boat but then you have to untangle it from your prop and anchor before you can leave.
It's nice to not have to deal with compressed air but is it better or even cheaper?
i will buy a atemregler for 26E and let my oelfree compressor running . the compressor has cost me 120 something Euro, makes up to only 4bar. think for diving on the hull it will be enough
While this product looks interesting, I see several issues. (1) The battery is not replaceable. This suggests the product is designed to be thrown away rather than repaired when an issue occurs. (2) On the main page, no members of the product team are identified for their familiarity with the design and safety of diving systems. (3) The "one size fits all" dive suit?? I'm not aware of any material that would allow one to make such a thing. When I looked at the Q&A, several people asked about this, but the answers were in a "don't worry, trust us" tone. Their response to this has me wondering how up-front they are about other issues. There is a similar product with replaceable batteries but a fair bit more expensive going by the brand "Blu3" - but it seems they have had some recall issues recently.
I would be very skeptical that this will end up being produced. I own three Nemos and one nomad and I can tell you by visiting the factory. It requires a lot of engineering to get a good system. The systems I have are very good and I don’t see how you could produce a decent system for 300 bucks.
There is a lot of thought and attention to detail which has to go into this for sure. They aimed to raise $20k and have instead raised $500k, so they have some decent funds to work with! God bless, Chris
@@SailingBritaly I hope they get it produced, I will be a definite buyer of multiple units but I will have to wait until they have a proven track record before I can put divers down with them. PS I I have really enjoyed your videos over the years.
When are we getting sailing vidz again? Btw First
That is a very good question and my best answer is "soon!"
God bless,
Chris
from what i remember about all those dive courses is that compressed air is, could i say, the "first" cause of problems. if the air isnt compressed but merely pumped, you can hold onto to it upon ascending because you wont blow your lungs. bottom time is a relation from the amount of nitrogen intake which varies for each depth (oxygen also has its thing by providing toxicity after 66 meters, due to its partial pressure within what we call "air", but one can train for this - im not advising that!-) so i wouldnt remember if 5 hours exceeds the bottom time for 12 metres deep. i can be mixing stuff that ive learn a long time ago so take all of this lightly.
the problem is caused by the fact the air is compressed by the depth and not in the bottle. when you breath from the regulator the air is not under the pressure of the bottle (or it will kick your brain out) but just "concentrated" by the depth. The problem arise when the bubbles expand in your blood before your body tissues can absorbe it.
@@ame2deo thats decompression sickness, "the bends", thats a different subject which relates.to.speed of ascent and the elimination,.thru.breathing, of the absorbed gasses in the blood stream. what you also refer to as concentrated is the reason why the deeper you.go the faster you will.consume the.volume of gas inside the.tank, ie, you.still.need a definite.volume.of gas to.sustain life but said.volume will be filled with a bigger amount of gas because the latter is.being.further.compressed by the surrounding pressure of water(depth). breathing pumped air isnt the same as breathing compressed air
@@pmnfernando nope. 1L of air in your lungs compresses while descending. so as you are breathing the same amount of liters you are taking in n-times the air you wouls have had on land. this means your blodd has higher concentraion of gasses. So as your body keep on absobing gasses at the same rate you have to give time to your body to absorb that extra gasses that are oversaturating your blood. if you don't do it that extra gas in your blood expand while climbing and so the decompression sickness arise.
Unless you are usin a trimix the air compressed in the bottle is ambient air..this is why it's crucial to fill the tanks with the cleanest air possible (therefore away from exhaust gas)
@@ame2deo i thin k we are talking in circles. you just repetead what ive said, wording it in a different way. i will refer to your first initial answer when you mentioned: "when you breath from the regulator the air is not under the pressure of the bottle".
what is happening is: the regulator 1st stage reduces 90% of said pressure and the remaining 10% are regulated by the diaphragm which also makes the air available "on demand" ie, when you need to inhale.
the air you are breathing is still compressed air from the tank plus being compressed, still inside the tank at the depth you currently are. this is the reason why, whenever we, for some reason loose the mouth piece regulator, are trained to continually exhale a stream of bubbles. why? because if you do inadvertently start to ascend , the exhalation will prevent the expansion of the gas inside the lungs thus avoiding a pneumothorax, or the beginning of it in the form of burst alveoli and tiny cappilary vessels.
trimix is a blend using helium because this gas is less narcotic that nitrogen, thats the reason why it is incorporated into the blend, thus decreasing the quantities of oxygen and nitrogen present. being less narcotic has a better effect in ones CNS.
Trimix is used to for tecnical deep diving, in conjunction with nitrox , air, and even 100% oxigen for some of the decompression stages, which will take hours!.
If the first stage decompress 90% and the second stage decompress the other 10% it sums up at 100% the air you breath when inhaling is at the pressure of the depth you are. Sending down from sea level or breathing through a bottle is more or less the same air. You said the air in the bottle is different from the regular air which is not unless is a mix. Nitrox or trimix. The problem arise when the absolute quantity of Nithrogen due to the compressed air by DEPTH, arise over certain level. Because your body can absorb just a small quantity. Because the difference between what you inhale and breath out stays in your body. Being Nitro 79% of the air, being you can absorb small quantities (while of oxhygen you absorb way more) it stays in your bloods for a longer time. This is why already at 20-30m you suffer from narcosis as your body is already at higher level of absorption of Nitro.
So. No the air you breath is compressed by depth. If a had regular dive within 20m your body is capable of absorb the nithrogen. Beyond that the concentration is too high and you have got wait your body to absorb enough to get its level to a safety threshold.
By the way at 12m you can dive not incurring in any problem other than lung damages due to holding your breath when rising up
very nice but not for me ps nice to see you