Nitrox – When to take the plunge…

A question that comes up quite regularly, but what is the right answer?

To give a proper thought, we must first look at the history and current events of Nitrox.

Used in a commercial setting for as long as there have been divers, nitrox didn’t come into mainstream use until the early 90’s and even then is was only really supported by “fringe” technical diving agencies such as TDI. In fact the British Sub Aqua Club (BSAC), the “governing body” of UK diving didn’t accept it’s use officially until 1994, after outright banning its use in 1992!*

Put simply, it’s the practice of using more oxygen in your breathing mix which in turn lowers the amount of nitrogen available to be absorbed into your bodies tissues while at depth. The result of this is longer no-decompression limits, shorter decompression times or the perceived safety factor if diving to air limits and a more energetic post-dive feeling. I say perceived, because when it comes to safety, it’s statistically null and as for the lack of lethargy, that’s subjective and difficult to measure. Mainly because if you dive enough to notice a difference, then it may be improved dive fitness rather than any benefit from the nitrox.

The downside of this higher oxygen, is far shallower depth limits than air and a requirement to track your cumulative dose of oxygen. For example: Air is 56m, Nitrox 32 is 32m and Nitrox 100 is 4, yes 4m!

Sounds simple, but is it…

Well, yes and no. While it is very simple to implement, it depends on your use as to how easy it is for the diver to manage.

If you are only diving on holiday with a guide, then it really is just a case of plugging the mix into your computer, then following the guide and any instruction from your computer during the dive.

Diving locally though is a different story. For one, you’ll likely be autonomous and not have a “higher being” watching your every move, leaving you free to make your own decisions about depth and time.

Diving on air, this isn’t such a problem as you are very unlikely to reach any of it’s physical limitations, due to your own decisions or not – tide for example.

On nitrox though, to get the benefit of using it, you need to have a mix that is as “strong” as possible for the maximum depth of the dive. This means that you have an absolute depth limit which lies inside recreational depths, that you must adhere to or face the risk of very nasty consequences.

A scenario that comes to mind, which has actually happened. You dive at Anfre post with north running tide. You pull up to a bobber and check the tide and notice a nice trickle. You know that because it’s half tide up, that the tide will continue in that direction. So you select a start depth of 20m, knowing that if you run north, the maximum depth will prove no more than 25m. After getting in the water, you notice that it’s getting slightly deeper, so you angle yourself into the tide slightly to make your way shallower, at this point you reach a steep slope and wooooosh – you’re in 40m!

On air, this isn’t a problem. You’ll either make your way up the line, or deploy your smb and head for the surface. Either way, provided you have the gas, there is no immediate danger.  On nitrox, you’ve just exceeded your depth limit by some margin! Alongside the danger of the nitrox itself, you now have an added danger of panic, due to knowing that you have exceeded this limit. Neither are good for your health, or an issue on air.

So straight away, we have 2 extra things that you need to think about before and during the dive. How deep am i going? (before) and How deep can i go?(during).

You’ll also need to need to make sure the mix in the tank is what you think it is, by religiously analysing it before every dive. Another step and thing to remember.

This is why nitrox was always considered a semi-advanced qualification, until it’s mainstream use got high enough to where the agencies could start to make money out of it without too much fear of it being dangerous. Now for example, you can use nitrox from pretty much day one, even on your Open Water course!

So to be a safe nitrox diver, you need to:

  • Have the knowledge of the dive sites to be able to know how deep they are, and once in the water be able to navigate a route that keeps you inside the limits
  • Have comfort around the methods of calculating the depth limits and tracking your cumulative exposure to the elevated  oxygen.
  • Have the confidence and skills to be able to control your environment and equipment while underwater. To make sure that you don’t get pushed around by the tide.
  • Finally, you’ll need to have a good comfort level whilst underwater, this will enable you to have a clear enough mind to make sure that you are thinking about these new limits.

So why use it at all?

For dives of 30-45 meters, you can nearly double your no-decompression time. That makes a big difference to your dive times, especially on multiple dives. Diving up the Platte scalloping in the summer would be almost impossible without nitrox, as by the 3rd dive of the day in nearly 40m the no-deco limits are just a few minutes.

Are you going to benefit?

Simply, if you are ending most dives because of low gas, then nitrox will be of little benefit. If however, you are frequently ending dives with plenty of gas left because you have hit a no-decompression limit, then absolutely nitrox is for you.

One final note, the nitrox courses offered by all agencies are “theory only” with dives being optional. I personally believe that this is a bad example of “bare-minimum” teaching, and will always make sure that my students get a dive in as part of the course. That way, we all go diving which is the whole point of learning, secondly, we can all make sure that we are happy with actually using nitrox. Also, be sure to pick an instructor that actually uses the stuff, the number of instructors teaching nitrox with no experience in using it is pretty scary!

As always, i’m keen to hear your thoughts on this. You can either comment below, send me a message or pop in for a chat.

Cheers and i hope to see you in the water soon! #nobullshitjustdiving

 

*from wikipedia, so probably wrong dates, but the gist is correct

Thrill Seekers, Finders Keepers, Losers Weepers…

It don’t need to be no deeper, it’s finders keepers – Mabel  – A great tune!

A few months ago, i posted this on facebook

“Went looking for something this morning on a secret mission. First run, lost my damn compass, which is embarrassing having labeled all the other recent “losers” as “tossers

Second dive went back and found it along with 2 more anchors! So not quite a member of the tossers‘ club just yet – well in that sense anyway…”

This post caused a bit of outrage, from people who really had no idea to what it referred to, seemingly because i was “being mean”. I’ve now since discovered that a couple of their mates had lost things this year and as such took offence and called me names. Which we’ve learnt from the modern political scene, is the first tactic of those that cannot debate someone with facts and knowledge. In fact, when this was pointed out, they deleted their comments which pretty much proves my point.

What the post actually related to is twofold…

First, there is a long-standing joke / banter between a few groups of active divers about losing shot-line anchors when wreck diving. The post above was related to this banter because i had actually found 2 anchors, which adds to my total of about 10 found this year while others have lost several. The anchors found were actually owned by a fisherman mate and have now been returned to him.

Secondly, there had been a recent spate of losses by some of the guys. The bloke i was diving with that morning had dropped a stage over the side while gearing up to dive the Bizon. Another had clipped a hang-tank with one of my regs attached to a lazy-shot on another wreck dive. Mistakenly he had clipped it to the wrong part of the line resulting in it working itself free during the dive and falling to its doom never to be seen again. There were several more this year, but you get the gist.

I believe that there is an important lesson here, which goes beyond just not losing your stuff…

There is a growing teaching method in the industry, that uses “absolute positive reinforcement” techniques. This is a teaching method, where all students are only ever given praise about the things that they are doing right, and never given negative feedback about things that they are doing wrong – yes i said it “wrong” it happens, we all make mistakes, especially when we are learning!

Now, this method might make you loved as an instructor by forming a circle of confirmation bias. By this i mean that you are a fantastic student / diver, so I must be a fantastic instructor. To say otherwise you might have to admit that you are not a very good student / diver and nobody wants to do that. There is nothing wrong with this, everyone feels warm and fuzzy inside, right?

The problem is that as divers, we are in constant battle with nature, while at the same time trying to harness physics to help with that battle. Your instructor and fellow divers might tell you that you are great, but nature won’t care about your super-made-up skills.

If you need to stop to adjust or fix something during a dive and the tide is running, it wont care and will continue to run.

If the gas pressure in your lungs is less than the water pressure outside, then the water will enter your lungs and you will drown.

Nature does not care and it will not feel emotion, it does what it does because of the laws of physics to which it abides. Period.

When it comes to equipment, sometimes shit happens, but most of the time it is a lack of something that causes the issue.

It could be a lack of knowledge in the equipment. Maybe it was bought over the internet, without the input of a suitably knowledgeable person and it’s not fit for purpose.  Or perhaps the kit is fine, but it’s been fitted or attached wrong.

Was the problem due to lack of maintenance or pre-dive inspection. I’m constantly amazed by the lengths people will go to just to save a few quid, remember, this stuff keeps you alive!

Are you properly trained or drilled in the kit. I’m definitely not saying that you need to do a course for absolutely everything, but have you tried it in the shallows in several different configurations before choosing what is best for you and have you consulted with your peers about that choice.

For an over the side drop, was it because the weather was too rough and you were falling about as the boat rolled, should you have been out there in the first place. Were you struggling on your own, because you’re stubborn, or are the rest of your team too selfish to help.

Was the kit that you were using suitable for the type of dive that you are doing. It’s all well and good taking 3 spares of everything, but sometime KISS is the best option. Are the bobbers on your line big enough to stay on the surface in the expected (or not expected) tide. Is your SMB visible, or is it one of those  (banned from my boat) yellow ones, or even worse stupid fucking 2 colour ones.

These are the sort of things that you need to be thinking about for every dive, regardless of what type it is. It’s obviously not exhaustive and i don’t think that you could ever document everything that might go wrong.

It’s all well and good giving someone nice words and a hug when things don’t go perfectly, but you are doing them a disservice. What you should be doing, is figuring out what went wrong, and how it can be avoided next time. Before there comes a time when there is no next time.

Everyone will be better divers in the end, and isn’t that the whole point?

Just a puddle, a Bloody Deep Puddle…

Dorothea

A disused and flooded slate quarry, found in Northern Wales on the Western side of Snowdonia National Park – a very pretty place if you’ve never been. Slate production was stopped in the 60’s and the pumps keeping the water at bay were turned off in 1969. Assuming that it takes a few years to fill up, it was probably dived in the 80’s and i know that it was dived in the 90’s. A private area and not an official dive site, there are no facilities apart from a carpark and a scaffolding jetty, apparently left by a film crew from a recent shoot.

As you drive in, you are greeted by a mixture of old slate and more modern block type buildings, all of which are in disrepair. I was somewhat surprised by the cleanliness of the area as it struck me to be a great place to hang-out as a youf and also a top site for the fly-tipping inclined. Just as you are getting bored of the buildings, you round a corner suddenly to be presented by a sheer drop to a water-filled quarry. This you soon learn is to be your dive-site – Dorothea herself!

Just a bit further, and you come to a small car park, which i’m told can get pretty busy on the weekends. For us though, we had it to ourselves during the week with only 3 or 4 other people there on the weekend. Maybe this was a special circumstance though, as we were in the middle of the “Great Storm” of October 2017 and it was the NEC dive show – bit of a strange week all round really, it hardly rained, and the sun was out on day one, which i think is almost unheard of in Wales!

There are a couple of areas to get in, and out of the water. The “beach” which is a mud slope leading to a fairly shallow area of the quarry, where you are likely to get the wagon stuck and all your dive-gear covered in sticky mud. Or a very steep “Slope of Doom” in the car park i mentioned earlier, so called because it is incredibly steep, to the point that I was amazed that I didn’t go ass-up trying to walk down in my twinset. We used the later for all of our excursions, despite the fact that you do need to be careful with potentially dangerous entry and exit points – for one, you could hurt yourself and curtail your ability to dive for a few days. Or perhaps worse, cause yourself a bend from the exertion at the end of the dive in walking up to the car. My “technique” after a trying a couple of the options, was to extend my deco a bit and resting on the surface for 10-15 mins  before making the climb with twins still in place and then come back for the other gear once changed etc.

I’d traveled over with semi-jerseyman Roger, and we had met up with Mark Ellyatt in Wales. The plan, was to do 3 days diving for certain, at two dives per day, with the option to stay on and fun-dive for 2 extra days. Roger, being from Preston was going to visit family for the weekend, but soon decided to extend his diving by the extra 2 days. For myself, i was in 2 minds about going to the dive show on the Sunday, but decided to stay and dive too.

We were all staying in a hostel called Basecamp Wales situated in a prime position for people hiking Snowdonia and only a short drive (even by Gsy standards) from Dorothea. Whilst the rooms were sparse, it was cheap, comfortable and had a great kitchen in which to cook bacon sarnies and a large lounge area which was invaluable for classroom work of an evening. Nearby was a small town with take-aways and shops for supplies – mostly Haribo sweets and many, many biscuits…

Each dive started with the required very-brief-ing and gear up, before walking all our ancillary gear down to the jetty, then getting suited up in drysuits, weights and CCR / Twinset before gingerly feeling our way down the Slope of Doom.

For dive one, we were all expecting the water to be freezing, so after making our way down to the water and gearing up, we were pleasantly surprised to find that the water was 16 Celcius! After climbing down the jetty steps, you find yourself in about 2m of water, so you need to float as you retrieve stages etc from the jetty just above your head.

Although there are many shot-lines dotted around the quarry, it’s very easy to descend straight from the jetty and make your way out to the desired depth. Straight off the end of the jetty it’s about 2m deep. Here in the warmer water,  It’s light but the visibility only 2-3m on average.  After a few meters, the bottom slopes off sharply down to about 15m where the water suddenly goes nice and clear, at the same time the temperature drops to around 6 – bit of a shock!

There are a few cars around this bit, and a van slightly deeper. If you head slightly to the left you come across a small open-fronted building which has been adorned with many gnomes and Christmas decorations! From there a right turn takes you into the main body of the quarry and the deep.

A slope then takes you down to about 25m, at which point I was finding it hard to mentally gauge my depth, often expecting that i was much deeper than  I actually was. Passing over some large hawser wires from the old workings, one small lonely tree and on to a broken stone drop-off on the right, with a more gentle slope on the left. Both of these routes bring you to the “cafe”, which is a small plateau in 40m with a table, chairs and icecream advertising board. From there you reach the ladder which is attached to a drop-off from 40 to about 65m, with a 50 road sign attached to the ladder at 50m. On this sign is some stickers with arithmetic problems apparently installed by the local BSAC club for their “depth progression” training using a similar method of narcosis testing as you find on the Padi Deep Dive – though slightly more effective in 50, rather than the 30 (ish) found in the Padi program.

Over to the left and ’round the corner of the ladder is a slope, which is where we found ourselves on our first dive with a maximum depth of 45m – a shakedown dive, which went without major incident. With the difficult conditions, and the fact that we were doing repetitive dives over multiple days meant that our plans were padded with a lot of artificial decompression. Further made safe with a plan of spending most of the bottom time in reaching our target depth resulting in very little time actually at that depth.

For some reason, we were struggling as a team to ascend fast enough, something that i normally pride myself on. I’ll just put it here, so i don’t have to repeat myself for every dive. I put it down to diving with a new team, and nobody wanting to crack the whip. I often found myself trying to keep everyone together as Mark “went ahead” and Roger “took his time…”

Day 1 went well, with no real issues, though dive 2 did get a bit cold with swimming around near to the 50 sign for what i felt was too long compared to what was needed to look at a ladder, sign and short cliff face! This dive I was also diving independent 12’s and my left reg wasn’t breathing very well which added to the discomfort – i serviced it that night, the perks of being a tech!

Day 2 we were joined by “Big D”, for a 55 and a 65. These also went well, apart from Rogers’ SMB reel deciding to pay itself out on descent, trailing out over the slope which took a few minutes to sort out – not a problem really as it meant less time at target depth and added to the conservatism of the dive plan. Mark actually thought it was sabotage on my part in an act of slowing the descent and congratulated me on my ingenuity –  i assured him that though a great idea, i couldn’t take the credit and that should go to Rogers dodgy reel…

Day 3, we were joined by “Little D” and his Kiss rebreather to do a 60 and 75. On the 60, D practiced his diver tow / ascent with the only available  open-circuit tosser (me), but i wasn’t the best student. The ascent was from 55m up to 40 at the “cafe” but i felt the speed was a bit fast, and it felt like i was out of control. Not wanting to get bent, i bailed the ascent and signified this by shouting “Fuck You”, dumping my wing gas and grabbing on the ladder! In D’s defense, it wasn’t that fast and he was in control, but in my defense it was day 3 and i was on OC. For the record, it was 55 to 40 in 1 minute.

Day 4 was just 1 dive, a lovely bimble to 85. This went really well with a huge cliff and reaching the bottom at target depth with something to look at. By this point, there is almost no natural light, but the water is very clear. The topography in this part of the quarry is spectacular, with the smooth rock face for nearly 30m sheer. The rock here actually looks like wood, due to the layers of the slate in the stone. This was my favourite dive, with a drysuit and cold-water PB and no worries, beyond the normal worries you should have being 85m underwater!

Day 5, Dive 8….

This was supposed to be to the sump at the very bottom of the quarry in approximately 100m.

Preparation physically was pretty good, well fed and watered and personally no alcohol for a week – nothing special at home, but normally whilst away i’ll have beer every night.

Dive prep was ok, but my gas could have been better. Due to running low on Helium, we’d boosted this, and transferred that to fill my tanks. I’d wanted 13/45, which on the bottom would have given me a P02 of 1.4 and an END of 50, meaning that it would have “felt” like i was in 50m when actually in 100. I ended up with 15/33, which gave me a P02 of 1.65 on the bottom with an END of 63m. I made the decision that it would be manageable provided that the workrate was kept low – END was no worry, and the P02 could be easily managed at such short exposure.

An important point, which which will come to light later, was that though we were diving as a 4, both Roger and I had stayed on to fun-dive, with Mark teaching with D. Though it was never explicitly said, it was the case that Mark would focus on D, whilst Rog and I would do our own thing. This is totally understandable, as 100m is no easy dive and there are many things to go wrong. It’s not fair to expect one person to take all the responsibility, without it being planned. It’s also fair to say, that whilst i’m qualified to dive that deep, i’m not experienced enough to hold any hands.

Time to dive…

We geared up as normal, apart from i would also be staging a 3L of 02 near to the jetty. At the very start of the dive, i descended to put it somewhere, and chose the boot of a car nearby in about 7m – I thought that everyone else knew that i was doing this, and had said what i was doing as i got in the water.

I returned to the jetty, met up with the others and off we went, this time with a surface swim over to the shot that led down to the “cafe.” Down the shot, down the ladder and then off to the Left, down the 85 drop-off and onto the slope to what we though would be an arch leading though to the magic 100.

As we swam down the gentle slope from 85m, we started to eat into our short 15 minute bottom time. I began to think that 89 would be our lot, so i went over to Rog and shook his hand, something i’d made a mental note to do before the dive, as i thought that he would like it and that it would be a good memory to have. Shortly after the hand-shake, it became apparent that we were not going any deeper before out bottom time ended, so we started to turn and head back for the cliff to avoid a super-boring mid water ascent.

At this point, we weren’t swimming hard, but we were moving. A combination of that hardish fining and the fact we had moved closer to the bottom for the handshake meant that some silt had be disturbed from the bottom and the vis was closing in.

As i made my right-hand turn i became aware that there was more distance in between the divers and because of the poor vis i couldn’t see everyone. I could however see Mark above me, so i knew i wasn’t off on my own.

At this point, due to poor vis and my high END, my narcosis level was very high. Of course it’s not something that you normally hear from any diver, but i’m not afraid to admit it. I felt in control, and i was still driving my bus, but i wasn’t paying much attention to others, or to continue the analogy, capable of helping you drive your bus! I could have ascended and lessened the narcosis, but i was worried that in doing this i would have lost reference to the bottom and if the vis was bad above perhaps lost everyone. So i kept in sight of the bottom until the vis cleared and then rose up to join the others to my right. At this point we were only at 11 mins ish, so there was no need to ascend off the bottom from a schedule point of view.

I was now back in control, with my head pretty clear. I looked around, to see that there was now only 3 of us. Clearly that cloud had not gone well for someone else!

I had a good look around, to make sure that i wasn’t crying wolf. Then signaled to Mark, who didn’t see the signal. Having only glanced about, I thought  that it was his student, D that was missing. I then looked back again and could dimly see a light, perhaps they are coming. This was when we reached the wall, i signaled to Mark that we were 3 and not 4. I then notice that it was actually Roger that wasn’t there, which gave me the best example of narcosis I’ve ever had….

We are still in 85 at this point, at the bottom of the cliff. With a largely high END, my thought was just “nothing i can do, i’m open circuit and near the end of my planned bottom time. At this depth any extension is going to ruin my plan and anything more than a few seconds is probably going to mean running out of gas and not being able to complete my extended decompression” To do otherwise would be silly, because at this point I have no idea what has happened to Roger, he could be absolutely fine, and i know that he’s experienced as a solo diver. He could also be dead. Either way, there’s no point to me risking myself.

As we ascended, at 10m per minute through about 70, my narcosis level dropped to the point where i felt comfortable and slightly merry. I started joking about in my mind, thinking “oh shit, that’s my ride gone” and “I wonder where the fucker put the keys” – at this point there wasn’t really a thought about how Rog was.

At around 60, the narcosis dropped another notch and i started to worry about what had happened. On a CCR as Roger was, there are lots of things to go wrong and really, i couldn’t think of a reasonable excuse for him to have left us. I also knew that he was really keen to do 100, and in the back of my mind i thought that maybe he’d blown the team and plan to try and get a bigger PB (89 was already a PB). This meant that i switched from worry to anger, with a split of maybe 90/10. Knowing that we cannot do anything other than complete our plan, means that we had an hour wait before we knew for sure.

So, in the space of 30m ascending, i’d gone through lots of thoughts and emotions, also remember that this is only 3 minutes!

At this point, my head clear, I started to “what if” and in my mind started to think about search and recovery, thinking whether Mark and I could stay in Wales longer, was there room at Basecamp, and how we’d need to get more Helium.

I then started to think about how and when to report it. Remember what i said earlier about who was responsible? Sudden;y i’m thinking about being investigated!

Those last 2 points were in my mind over the 60 mins or so of decompression, believe me, i didn’t want to think them, but it’s a long time hanging about not doing much.

There was also a point where we lost D at about 15m, by this point it was back to joking with Mark – what the hell was going on!

After a minute of so, we reunited with D and carried on searching for the jetty slope, this dive we had come up a slightly different way, so weren’t sure which way to turn. As it turns out, we went the wrong way.

Obviously keen to reach the surface and see if Roger had made it, Mark was able to switch to his computer for real-time deco on his CCR, so he left D and I to finish our decompression schedule, taking a compass reading and heading towards the jetty. On completion, we surfaced to make sure we were heading the correct way and then went back to 3m for the swim back – which is why there is 2 “teeth” on the profile, in case you thinking it was poor buoyancy!

As we near the jetty, we shout to Mark asking if Roger is there, or if he can see him. The answer comes back negative. Remember, that he is on a CCR, so no bubbles to see even if he is alive.

At this point, there is nothing to be done apart from focus on my own post-dive stuff. I remember that i need to go and retrieve the pony of 02 from the boot of the car. I descend onto the 4m slope by the jetty in search of the car – the vis is pretty poor here and i’m not exactly sure where it is.

Boom… I come face to face with a diver, and he’s wearing a rebreather. At first i think that D has followed me down, but no it’s Rog!

I’m really happy to see that BASTARD! Fucking Really Happy to see That Bastard!

I pop up to tell the others, before going back down. He looks quite happy, he’s not showing the worry that we 3 have done for the last hour. And to top it all off, the Bastard is gleefully carrying MY pony that he “found” in the boot of the car! Turns out he hadn’t heard or seen my staging it in the first place. So if i had have extended my bottom time and needed the pony for my deco, it wouldn’t have been there, not good!

I’m not a parent, but can now imagine what it’s like when a small child runs off. When they come back, you are both relieved and angry with them and not sure whether you should hug or shout and scream!

Afterwards, Roger said that he saw another cliff as we turned, so thought that we should continue up that side for a different view on the return. That’s it!

So the lesson here, is

FOLLOW THE BLOODY PLAN & STAY WITH YOUR TEAM!

Unless there is a problem that makes you deviate. Anyone that knows me knows that i’m a big fan of solo diving, perhaps there is call for it in this type of diving. With that, at least everyone knows where they stand

So, a great week and a fantastic experience, one that i’ll remember for a very long time!

Thanks to Roger, Mark, Big D and Little D for a great few days. Special thanks to Rog for the lift.

Hopefully we’ll be back next October 2018 – Let me know if you fancy a trip!

For more pics, check out the album…

Episode 3 – Wrecks & Rebreathers with Mike Paige

This episode i’m joined by Mike Paige, a prominent local diver with a passion for wrecks that has experienced most of the diving Guernsey has to offer.

We talk about his recent change over to a rebreather and about some of the wreck diving that he has done. Links to the videos and other media mentioned are posted below.

Links:

Youtube Channel

Wreck of the Forth

Wreck of the M483Source Karl Taylor

Wreck of the St Malo

Dorothea Quarry

Blog on Rebreathers as a buddy

Full-face Snorkel Masks – Thoughts

With popularity growing amongst users in the warmer oceans of the world, we’ve been hearing quite a lot about full-face snorkel masks (ffsm) this year.  Perhaps strangely, it’s the watersports retailers, rather than the dive shops selling these things. One of the largest diving manufacturers only makes them branded for their sports line, rather than their diving brand. Is it some big conspiracy, or something else.

Here’s what usually happens…

Someone will come into the bunker and ask if we have them, we will answer that we haven’t and go on to explain what we don’t like about them based on our experience. They then say that they’ve used one on holiday and that it was amazing. We agree to disagree and away they go, presumably to purchase one online.

A few days later, they come back in to ask about anti-fog. We say that there is a compound we use on a standard mask, but that we don’t think it works on the ffsm type from what we have seen / heard / experienced. They buy the anti-fog and away they go again.

A few days later, they return, admit that the ffsm is a heap of junk and buy a normal mask and snorkel. This has happened many times this year…

So, here is what we think…

The general rule with diving equipment, is that stuff that is designed to work with the water, works better than stuff that is designed to work against the water. Now i will admit that both a normal mask, and the ffsm are designed to work against the water, but a normal snorkel is designed to work with the water and that makes a difference.

With a standard mask, there are many, many variations in size and shape, with a ffsn, there only seems to be a couple – S,M, L – which isn’t enough. This makes good fit an issue, unless you have a perfect face for the ffsn.

A standard snorkel is just a tube with a mouthpiece, it is designed to allow water to flow in AND out very easily, meaning that with an easy technique, any water entering the snorkel can be easily blown out. Even if the diver fails to do this, it can be very quickly spat-out allowing the diver to breathe again as nature intended. This cannot be done so easily with a ffsm.

To allow the ffsn to have the best chance of fitting, it needs to have a substantial strap that covers most of the back of the head. This strap needs to be pulled tight, to keep the heavy (out the water) and bouyant (in the water) ffsm in place. This means that if you do get water in it, or need to remove it quickly for another reason, it is difficult and could easily (in my experience as a diving instructor) lead to a panic situation. Not good in the middle of the sea.

I mentioned above about the fogging. This is caused by warm moist exhaled breath condensing due to temperature change on the lens, as a ffsm has a lens made from plastic, it will tend to fog more than a standard mask because it (unless it’s cheap rubbish) will use tempered glass. The other big factor is that a normal mask is only connected with exhaled breath when the diver breathes out through their nose, which should only be done for a specific task such as equalization or water clearance rather than each breath. This leads on to one of the biggest problems in snorkeling…

Snorkeling is very easy, and for the most part people pick it up very quickly without any real training. Historically, i believe that most people would have only tried snorkeling locally if they had an interest in other aspects of the sport or experience in the sea. Or maybe they were introduced by an experienced mate who showed them the ropes. Now though (and this is a good thing) snorkeling is readily available to more people and some of these may not be very comfortable in the water. If you are not comfortable in the water to start with, then you shouldn’t be having a go without proper instruction. Whether this is from an experienced mate or proper instructor makes no difference really, but you need to make sure that you know what to do and how to do it.

Anyone wanting to know more about the basics, can take a free online or app based course with SSI through us by clicking here.

The bad points of the ffsm don’t end there, there are also technical / physiological issues.

Breathing is the act of air being pulled into and pushed out of your lungs. On it’s journey, it needs to pass through your mouth and windpipe down into the capillary laden  air sacs in your lung tissue. These are where the gas exchange of oxygen (in) and carbon dioxide (out) takes place. Any area other than these air sacs is termed “dead air space” and has no respiratory benefit – other than filtration etc, but for the purpose of this that’s a bit too “deep”

Dead air spaces are important in diving, because we are adding to them with any breathing apparatus that we use. This means that a larger proportion of our breath is doing nothing in the way of bringing in oxygen or expelling carbon dioxide. There is no 2 ways about it, the ffsn makes this worse!

The problem with lack of oxygen and too much carbon dioxide, is that you can initially feel out of breath, often this leads to a more rapid but shallow breathing pattern, which in turn adds to the original problem. If left unchecked, it can lead to unconsciousness, and in water that normally means drowning. With a normal mask and snorkel, you can just spit the snorkel out and easily push the mask off your face, this is not so easy with a super-tight ffsm.

I’m not saying that these incidents are very common, with a little research i’ve found a death or 2 which cites a ffsm as a factor, but who knows the actual truth of the matter.

From usage point of view, the ffsm also fails. You’ll struggle to dive below the surface, which is the general progression as a snorkeler. Firstly, you’ll struggle to equalize your ears, which for most people means a maximum depth of 1.5 meters, unless you want to hurt your ears. Secondly, even if you can equalize your ears, there is the problem of volume of air in the ffsm itself. This needs to be equalized as you descend with air from your lungs. In a standard mask, this only equates to a few ml, but in a ffsm it’s a lot more.

So to sum up, the ffsm is: Uncomfortable, heavy, leaks, fogs, stops the diver from progressing and may even be downright dangerous.

The best way i believe, is to get a good quality standard mask and snorkel that fits and learn to use it properly. You’ll enjoy it far more in the long run, and you never know it might lead you into more advanced snorkeling / freediving or even SCUBA diving being a big passion in your life.

If anyone wants to learn more about this snorkeling (or diving), you can send us a message, or pop into the bunker for a chat. You can also sign up for the totally free, no strings attached online courses here – you’ll just need to register “Dive Guernsey” as your affiliated center, don’t worry we wont spam you!

Episode 2 – History and Shipwrecks of Guernsey with J P Fallaize

The second Dive Guernsey podcast, recorded Weds 15th November in the Dive Bunker.

J P Fallaize is a keen local diver, with an interest in local history, with a particular focus on shipwrecks.

In this episode, we talk about the shipwrecks of Guernsey and the surrounding area. With a particular focus on the work involved with researching, finding and classifying the wrecks.

We then go on to talk generally about the diving that we do and the people that we do it with.

This is only my second podcast, so i’m very much in the early stages of learning. About 16 minutes in, i was worried about making the full 45 – next thing i knew, it was nearly midnight, and we had recorded three and a half hours! So if it’s a bit slow in the beginning, please bare with it.

For more information on the wrecks and history discussed, check out JP’s facebook page Bailiwick of Guernsey Shipwrecks

For videos of the wrecks discussed, swim over to the Dive Guernsey main site and browse through the Wreck Diving page and our Youtube Channel

A quick reset does wonders…

Following a great post and video by Karl Taylor about his thoughts on local diving and how to describe his experiences to others got me thinking. So this is the story from just 2 days of this week….

Having a slow boat, being winter and the need to catch scallops on almost every dive means that for the last few months we’ve pretty much stuck to the East coast between St Sampsons harbour and St Martins point.

Mick has 2 weeks off, the plan was to hit the scallops at the start of each week, make sure that the “week’s good” with orders filled and then explore a bit, maybe a wreck or 2 and try and scope out some new spots for the coming summer – hopefully find a thick scallop bed in 40m, yeah, right, keep dreaming.

Day 1, Tuesday. Disaster! First tank down Gabrielle way in “bend alley” and the vis was disgusting, horrible, total shit. The bottom was covered in the dead algae snot stuff, so thick that it covered the scallops and made everything very green and dingy. So I came up, threw all my toys out of my pram and did what I always do when the vis is bad. We headed for Sark.

Of course, with such thorough advanced planning, we got to Sark at completely the wrong time. No matter, we’re here, have gas, will dive! I picked a spot on the plotter that looked vaguely interesting and jumped over the side. The first couple of minutes were rubbish, but at least the vis was good. Then someone turned up the dimmer switch as i came to lovely soft, bright shell-beach like shingly stuff and decent size undulations (waves in the sand around 2 feet high).

It was beautiful, mooching along with a trickle of tide, surrounded by a shoal of thousands of sandeels without a care in the world. Then came temptation in the form of flatfish. The first was only a small Brill of a couple of pounds, so that was no hardship. Then came the big fella, biggest fish i’ve ever seen. It was a Turbot and i grabbed hold of it to see just how big it was, a good 2 feet long and easily 3″ thick! Maybe 20lb…

I should explain at this point that it’s not allowed to take anything by diving in Sark waters. Though it hurt to leave, it was nice to see and and I still loved the dive anyway. Hopefully no dangler catches it next week and that it lives to get even bigger and moves over to Guernsey – Whack! The dive finished with some lovely reef and a few massive yellow sponges. Lovely.

Dive 3 of the same day was a quick explore on the South-east corner of a rock called Goubinere. This is a place known for flatfish, but there was too much tide. Bouncing along and crashing head-first into soft sand can be quite fun in the right mood, and i found a big anchor, I wonder if anyone has seen it before?

Day 2 came, and still with my toys very much out of the pram as far as scalloping was concerned, we headed for the South coast, always a dangerous move with dodgy vis. The general rule is that the East coast is the base, the Platte is 20% better, Sark 50% better and the South, well it’s normally 50% worse! But still, the wind was NE and South would give us some shelter. And i wanted to wet my spear…

Mick was first in, came back empty handed and announced that the vis “was shit” hmmm. As we we had come all this way (about an hour) I decided to have a go anyway and i’m glad i did, a decent Turbot and a Dover Sole, fish for tea!- Though not for me, eurgh…

So, we’re off to a good start, next dive was a “lucky-dip” where we just drop into a random place and see how it goes. My dive was awesome!

As there was a chance of scallops i took the sack, landed in 46m off to the South of Longue Pierre rock. Hit the bottom on really black rock and my initial thought was, Bollocks, this is a wasted tank. But then a few seconds later I came to the end of the reef and onto nice bright shingle.

I skirted the edge of the reef and soon the sand started to form a slope, before long this slope became a sheer (ish) wall that stood maybe 60 feet up. Picking up what few scallops were there, i continued to “fly / float” along this Grand Canyon type place. As the vis was clear like gin it was brilliant. Imagine hang gliding in the Grand Canyon with birds close by and you’ll be close to the feeling. Amazing.

Somewhat refreshed by these few dives. dive 3 and day 3 reverted back to scalloping and all is now well with 2 tanks with scores of over 100 scallops today.

So what are you waiting for, get wet! If you’re bored of it, try something new, it still works for me after 15,000 or so dives, so it should work for you too.

On that note, i’m off – diving in 7 hours 🙂

Oh Nikola, you can be a difficult bitch…

There’s one local wreck dive, that the mere mention of can have the local rusty diver turning their nose up in scorn or perhaps even full-blown disgust. The Captain Niko…

Built in 1948 she sank in 1973 off the West coast of Guernsey. En-route from Rotterdam to Alexandria with a cargo of Ammonium sulphate fertilizer. Full story here

In the early days she was heavily dived and those that visited talk about a pristine white wreck – a lovely dive apparently that you could practically see the wreck from the surface.

These days though, you’ll struggle to get anyone to dive her, normally the reaction you get is along the lines of, “The Niko? It’s shit”

For me though, I like it. There are a few bits of the wreck that make Havelet bay seem exciting, but then it is a very big wreck. It was a big ship to start with, and now that it’s broken up a bit and spread out it makes for a huge site. As it’s mostly 50m ish, you couldn’t swim from one end t’ other in 1 dive, well at least I don’t think I can.

The offending part is a huge bit of hull that sits at around 30 meters, it’s just a perfectly flat area around 30m long. If you try and dive this bit or if you end up on top of it during the dive, it’s pretty much game over for that dive as there is no point in trying to find a better bit to dive within the allowable time.

In the past couple of years, we have managed to mark a few of points of interest. One is the bow, which is broken away but intact and upright (ish). As it still has all it’s winch gear etc attached it’s pretty much a dive in itself. The second is a part (i think) just behind the main wheelhouse that I dived with a BSAC club that came over in 2016, as i was only there as “shot-bitch” and to skipper their RIB, i didn’t have much time on the wreck. There seemed to be lots to explore there, including a big doorway which beckons for a more thorough mooch. Lastly, there is the wheelhouse itself. I’ve only seen it once, and not for long as it was at the extreme of my range from the shot-line, again there appeared to be plenty of places to get stuck in to the rust.

While i’ll admit that the wreck must have lost some of it’s sparkle in the 44 years on the seabed i think there is life in the old girl yet.

The thing is though, she can be a cranky bitch. Often when i’m describing local wreck diving to new divers, i’ll say that the Cement Wreck (30m) is a nice friendly wreck and that the Ammo (30m) is a more advanced “foreboding” wreck. This is probably down to a few different things, the bottom type and it’s ability to reflect light, the amount of slack tide and the general area of the wreck (the AW is right outside the harbour and can be stressful with the amount of close traffic). The Niko somehow manages to be both. One day she’ll be a lovely welcoming wreck, and another day without any real reason you get the impression that she doesn’t want to be disturbed. Infact, on a couple of the times i’ve dived her, i really felt that she was doing her best to keep me there for eternity!

The main trigger for this blog, was a dive that i did a couple weeks ago. As I said above, i’m still trying to build the mental picture and marks on the plotter for the wreck. As it was just me, I decided that it would be a good idea to “free-dive” the wreck with no shot-line, just a delayed SMB to enable me to drop on the stern and see where i could get to. I dropped down quickly to not miss the wreck entirely, landing on a part I think was just up from the stern. Happily the vis although not amazing was pretty good at maybe 6/8m. So there I was, merrily drifting along the Southern side of the wreck for around 8 minutes, there was very little tide so i was swimming in an effort to cover as much ground as possible in the short dive that I had (sort of) planned. Much of this “plan” revolved around the fact that i’d left my 02 at the bunker and therefore had no inclination for a long back-gas decompression in the 11 Celsius water. Brrrr…

So there I was, happily swimming along the wreck, vis was good and everything else was going well. In front of me was some lost crab-pot rope, floating off the wreck a few meters in a tangle. Now the last thing you want on a 50m dive is to get tangled in this heavy 14mm line, so as soon as i saw it, i made a sharp turn away from it. At that point, there was a big “gust” of tide and whoosh… No more wreck!

The wreck had just damn vanished!  The vis was OK, the tide was back to a wee crawl, and it is a big lump to find especially with my fairly good sense of direction underwater. But no, no wreck in sight. Weird. Very Weird.

I swam around for another couple of minutes trying to find it again, and just couldn’t. The other weird thing, I was diving it on the Southern side, after the high-water. This means that the tide would have been flowing NE, and then gone N-NW-W-SW as it turned to ebb (as far as i understand the area), therefore, any tide would have pushed me on to the wreck, not away from it!

I have a theory as to why a lot of divers say that they hate the wreck, I think it’s because they’ve had a dodgy moment on the wreck like I have and decided not to go back. One part of the problem is that the Niko is often touted as a wreck that you CAN dive on any size of tide, while the others are only doable on the neap tides. I think that this means people try and dive it on the bigger tides, which causes the issues. I’m going to try and get there as a priority this year to get a better understanding. The only problem with that plan, is that the St Malo is not much further out, and I like the St Malo very much…

In conclusion, give the poor girl a spin, she’s not that old and you may even like it. Just be sure to have your wits about you and don’t try to dive the bit that looks the shallowest on the sounder.

Video 1 – Video 2

Episode 1 (pilot) – Talking Local & Holiday Diving with Olly and Ryan

 

 

The first ever Dive Guernsey Podcast. Recorded at Olly’s house, in front of a open fire (sorry for the  crackling) on a hungover Sunday over a couple of wines and ciders. We aimed for 45 mins, but had to stop after 3 hours!

We talk generally about diving in the Channel Islands over the years, with a focus on scalloping. We also briefly and somewhat erratically discuss some of our favourite and  not-so-favourite holiday destinations.

Clearly a factual program, you’ll learn such things as:

  • What constitutes “Dog-Shit” diving
  • How not to react to an unruly child on a flight
  • What fun it is to watch Irish people being sick on a dive-boat
  • Why you might need a shitty stick and a second tank on a diving course

Narcosis – Friend, Foe or Both…

Now, I know that this will get controversial, but that’s kinda the point isn’t it?

I’m talking narcosis, or as the textbook puts it Nitrogen Narcosis. Though if we were to be technical or even pedantic, we’d call it Inert Gas Narcosis. This is because it describes the narcotic effects of all gasses, especially the inert ones. Inert means a gas that has no chemical influence on the cellular chemical reactions that keep us alive. This excludes Helium though, which is an inert gas added to the mix to reduce narcosis – and lower the Oxygen level for very deep diving, but that’s for another day.

I’m going to split narcosis down into 2 contributory areas: Scientific / Chemical and Outside factors, which I believe almost have an equal responsibility for what we actually feel in the water. I’ll then talk about the things I have observed over the years.

Scientific / Chemical

As we all learnt in our first dive class, divers are subjected to far more pressure than normal. Over millions of years we have evolved in a pressure of roughly 1 atmosphere, which is approximately 1 bar or 14.7 psi. We also learned that as we descend, we encounter an extra 1 bar of pressure per 10m of water depth (in salt water, fresh is 10.3m). To put this into context, to gain 1 bar of pressure we only have to descend 10m or 33 feet. To lose 1 bar of pressure we must ascend (in air) to something called the Karman line, which is the place where our atmosphere essentially stops and the pressure becomes almost zero. Though this is actually not quite far enough, it’s close enough for our purpose today and it stands at a whopping 100 kilometers, which in old money is 62 miles or 330,000 feet!

I digress (but fascinating no?), back to the diving.

As the pressure increases, the molecules of the gas we breathe are squashed together, meaning that when the gas is delivered to you, it’s at ambient pressure. This is worked out using the simple formula: Depth / 10 + 1. So at 25m, the gas is being delivered to the diver at 3.5 bar. This means that you are getting a much higher concentration of the gas molecules at depth than you would at the surface, the factor is the same number as the pressure, so using the example above, you are breathing 3.5x the molecular quantity or total mass.

Narcosis is caused by the gas being absorbed into the divers tissues and slowing down nerve transmissions. Essentially meaning that the electrical impulses within your brain are delayed to or even missed on the receptors. It’s thought that it happens throughout all your other tissues too, but this is only conjecture and of little importance. With the pressures encountered at normal diving depths, this is only really enough to slow down your thought processes and make you feel a bit “tipsy” but at very high pressures it’s believed to act like a powerful anesthetic and could knock you out.

So when we bring these 2 bits of info together, we have a formula to “explain” narcosis. We take the percentage of the gas we are looking at and multiply it by the depth to reach a “narcotic factor”. For example, if we use air – 21% Oxygen (02) / 79% Nitrogen (N2) – and look at just the 79% N2 at a depth of 30m we end up with .79* x 4 = 3.16 which we’ll call the narcotic factor, though those that have knowledge of nitrox will know that it’s actually partial pressure.

We can also do the same for other depths: 10m (1.58) 20m (2.37) 30m (3.16) 40m (3.95) 50m (4.74) 60m (5.53) & 100m (8.69)

*As we are working with a percentage, we express this number as a decimal, it’s not absolutely necessary but makes for simpler numbers.

From this we can then say that most people will be fine with a factor of 3.5 (34m), and that some people will be fine to up to a factor of 5. This is where the personal preference comes in. Out of interest, the maximum air record is 145m set in 1993 by Bret Gilliam** which would give a “factor” of 12.25!!

** There was apparently a dive to 155m in 1994, but this was very controversial and led to Guinness stopping the SCUBA air depth record.

So if you are happy to dive air to 40m, then you are happy with a narcotic factor of 4 (0.79 x 5). Which is the general gist taught by all the agencies, though they may not explicitly say so as it’s built into the recreational depth limits.

So far, we have just looked at air, so what about other gasses. Well, if we exclude Oxygen for a minute we can say that all gasses give a narcotic value in relation to their atomic weight or mass (there are other factors, but mass is the main one). So for example, if we ignore everything but the narcotic value, then we can say that the most narcotic is Radon with a mass of 122, and the least is Hydrogen with a mass of 1. So from this, as Nitrogen has a mass of 14, we can say that Radon is 8.7x more narcotic and Hydrogen is 14x less. Whilst Radon is definitely not used in diving, Hydrogen can and has been in the past, though it’s felt to be a bit unstable with it’s willingness to blow up – see Hindenburg! A gas that is commonly used is Helium with a mass of 4, so that does work out to be the best choice as it’s 3.5x less narcotic than Nitrogen.

With Oxygen, although it is actually more narcotic than Nitrogen with a mass of 15, it’s thought not to have much affect due to the different storage, transportation and use in the body over the inert gasses.

 Outside Factors

I believe that when it comes to narcosis, the mathematical ” narcosis factor” plays only some part to it. In researching this, I came across a Wikipedia article that stated “no diver will every build up tolerance to narcosis”                                     I think that this is total rubbish, as when I was scalloping full time and diving 50m every day, I felt great doing it. Now that i’m not doing it so much, the narcosis is definitely more evident.

When I think back to my deepest local dives, some of the best ones have been 58m on air. When I say best, i’m scoring by: clarity, fluidity, ease of sending the shot up, tying knots, wreck navigation, finding the shot, focus on plan & time, gas management, problem solving and everything else about the dive.

At the same time my worst ever dive for narcosis was at 45m on trimix. It should have felt like being at about 28m, but I was off my tits! I put this down to several factors in descending importance:

Rushing to get in the water. We were on a boat with about 8 other tech divers and I was team of 3 others. So after running about helping 8 others to get in the water, I was left trying to manage all my own stuff alone. At the time it was twin 10’s and 2 deco gasses. Also, the boatman had told my team to get in the water and i could see them struggling in screaming tide at the surface so i was trying to get in asap.

Speed of descent. I think that this plays a massive role in onset of narcosis, and although it’s related to the “narcosis factor” it’s not often talked about.

Light & Visability There is no doubt in my mind that narcosis effects are stronger when in low light and visibility conditions. It’s one of the reasons many warm-water divers get a shock when they dive locally.

C02 & Workrate One factor that is coming into common knowledge and teaching is that excessive amounts of C02 will worsen the narcosis. It’s thought that C02 is a catalyst for many of the diving nasties, though not much is known about the exact mechanics of it as so little research is being done. C02 levels are lifted due to either excessive workrate and poor breathing through technique or poorly maintained equipment – and rebreathers, but that’s beyond the scope of this.

Observation

With this section i’m hoping that some other people will write and add their personal experiences as they may be different to mine. Below is  written as my own feelings and what I have witnessed in others.

Personally, i’m quite happy diving to normoxic depth limits on air. In other words 57m ish. Having done these sort of depths literally hundreds of times, i’m saying this with the experience to back it up. Though we don’t really get the opportunity locally to go deeper than that easily, I think that it’s the limit for me. That said, on one dive in Jordan, I switched from Trimix to air on ascent at 66m and that was fine too.

For me narcosis used to be fun and enjoyable, i’d find myself in a heightened mood in the deep as i went about my business. These days a lot of the time i don’t really feel it,  on the worst days it just tends to add a slight fuzziness that I need to concentrate a bit harder to overcome. I honestly cannot say that it ever feels anywhere near dangerous to me on a good day – more on this later.

Anyone that has been to 30m+ will have experienced some level of narcosis, many though will say that they haven’t. They did, they just didn’t know about it because for most people it’s no big deal. It’s often that you’ll hear people draw parallels between narcosis and alcohol, which is a good way to explain it. In small quantities, it makes most people happy and allows them to get more enjoyment out of whatever they may be doing. Of course, in large quantities it can lead you to do stupid things and lose your mind. There has to be a personal limit.

One thing that i have heard a few times over the years as i travel, is the resort instructor telling students to not go below 30m or they’ll “get narked”                  I can never sit back and listen to this so will argue the point. It’s not that i want everyone to dive deep (for one they’d be in my way), but at the same time I don’t like the idea that people are scared of an imaginary line and that if they ever venture to 30.1m they’ll get knocked out as if they have just been caught by a McGregor left hook.

The other story that gets told often is that a diver suffering from narcosis will try and give their regulator 2nd stage to a fish. Now, i’ve not witnessed this myself, but I have heard it from people i trust. I think that if this does indeed happen, I don’t think that the diver thinks the fish needs the reg, I think that the diver does it for a joke, and as they are “narked” it tends to go wrong, or at least be taken the wrong way.

One person that I used to dive a lot with used to get an experience that he called “nitrogen psychosis” Essentially, when at depths over 40m he used to think that everything was out to get him and was going to go wrong – air was going to run out, reg was going to stop working, shark was going to eat him, he was going to get the bends, that sort of thing. Obviously, he stopped diving deep once he decided that it wasn’t a one-off as that’s not a good state to be in underwater!

Another that I used to dive with a lot, got such a high from the narcosis, that he would be in an amazingly good mood for the whole dive and even afterwards – he would often be seen with a big grin on his safety stop singing along to a tune in his head started on the bottom!

Where narcosis does get dangerous, is when it distracts from the important things like the monitoring of gas and deco obligations. Which is why it’s a good idea to push yourself under the supervision of an instructor or buddy that is far more experienced than you in diving those depths and more likely to be actually paying attention to you, rather than being too busy with their own stuff. It’s silly to think that an instructor can dive in Havelet a couple of times a month and then be on point in the deep! One time I was with a student on a 40m dive. We came across a lost parlour pot and I had a quick look in through the mesh (nothing inside) and then “stepped” back to allow the student to do the same. He then spent the next 5 mins looking into the pot from every possible angle multiple times, as if there was something really interesting in there. I was convinced that he was narked and to prove my point, I allowed it as long as I could and then called for him to follow me. By this time we were at the end of our bottom time and were ready to ascend. I don’t know how long he would have stayed looking without the intervention, but from a decompression and gas perspective it could have led to an issue if it had been another 5 mins. Once back on the boat, I asked him about it and he was adamant that he’d had 1 quick look and then carried on!

As I think about all the divers that I know, there is quite a varied “tolerance” to narcosis, I know some people that don’t like to dive below 40 without Trimix, and that’s perfectly fine. It’s all about personal choice, provided that they remember that Helium only reduces narcosis, it doesn’t effect or enhance any other skill. As Mark Ellyatt quotes on his website “Helium provides only sobriety, not experience or buoyancy skills!”

So… Please absorb your inert gasses responsibly…