Twinning

[Driftwood]

Hey Bren,

Cheers for the reply. I was getting kinda confused as to what the Adv. Nitrox offered with TDI over and above. Yes, I remember the Ammers headstagger and that was where I got the impression that you learnt extended no-deco times by switching to pure O2 at 6m...

Just goes to show the inherant problems of extrapolating someones past comments out of context eh?

So cheers guys (Ammers and Brenners) for the straightening out - it really didn't help that deco procedures using nitrox is listed in the course syllabus on the TDI website! Urgh!

Dave, Heads & Co. (and your cronies Bren if anyone is up for it?) I'm going to speak to Andy and try to sort something..... Watch this space!

PS Brenster - what are you going developing gills and blowing into the tank? How in God's name do you get 80min out of a 12l? I can squeeze an hour out of a 15 but only sub 20m on the whole dive - I know I horse my air a bit but you sound like your tidal volume is the proverbial gnat's fart!

And #### Yeah! Three Star Drift!!! Yeehaw!

:yelclap: :nuts: :dance: :bang:

PPS It's 04:29 and I see :sunshine:

(Edited by Driftwood at 4:30 am on July 15, 2002)

[Ammers]

I should point out at this stage that I NEVER had headaches after diving, the problem I had with 02 was dizziness on 100%. I have extensively researched the causative factors which can range from tiredness to low blood pressure. I admit to being tired a lot but that's lifestyle generated via trying to cram a lot into a small amount of free time. This is unlikely to change in the near or distant future. Also not helped by people constantly calling me at ridiculous times like 4 AM in the morning whilst bored in hotel rooms (yes Tierney I mean you). I now set my phone up to silent except for work numbers so that I cannot be contacted unless it's a work emergency. I also have low blood pressure although I have been advised by a diving physician that this is considered normal for young females. Now that I have built up a "tolerance" to strong oxy mixes I don't have any problems at all.

If anyone has headaches after diving there is a possility of hypercapnia or incorrect breathing technique, which can facilitate uptake of CO2 therefore causing a headache. I haven't experienced this myself however I know people who have.

Dizziness and headaches are two differing indicators of two different types of problem and should not be confused.

Using 100% at 6 m for 25 mins is generally pointless and is considered damaging in the long term - air is fine for a dive of this depth and duration.  On the subject of tank pressures, while I am not going to advocate, recommend or condone overblowing, it is possible to overblow 232 tanks to 300 bar quite easily and will result in an excellent fill once cooled, easily 250 bar. I have blown my tanks up slightly past 300 bar, gone in for an hour's cave diving at avg depth 10 metres and come out after using 30 bar, to find myself still above working pressure!! I can go into detail on mechanical implications of overblowing if anyone is interested? (I can almost hear the yawns)

Drift if you want to discuss the deco stuff give me a call. I can assure you that my information is correct. Andy confirmed that I am the first student he has ever had who has scored 100% in EVERY written TDI exam taken to date - a personal best which I intend to carry through to Trimix. I am not happy with anything less than 100% and obssessive about technical information, so you can be positive that I will not propagate incorrect info. In fact give me a call anyway so we can discuss the arrangements for Ireland. I'm in meetings all day but I might get a few mins where I can get in touch. Cheers.



(Edited by Ammers at 6:31 am on July 15, 2002)

[Mr T.]

Jeeezzuzz!!

Good on fact, better on fiction. Go girl, and what ya don't know, make up.

[Ammers]

Eh?

Why make something up when you can find out the right answer? Isn't that called laziness? So you're saying you are lazy, right?

Maybe making it up as you go along works for you Brenster but it ain't MY style brother.

I'm into PRECISION information, don't like to be guessing what's up next. Moving swiftly on.....

(Edited by Ammers at 4:44 pm on July 15, 2002)


(Edited by Ammers at 4:50 pm on July 15, 2002)

[Jay]

Get a room you two - honestly! Just to clear up a point from Bren's post (that may just be the way I'm reading it so apologies in advance) - your air consumption on nitrox will be the same as on air (or there abouts). Having increased O2 onboard will not reduce your breathing rate (as it is CO2 that triggers your body's breathing reflex). Not implying that you are wrong Bren but reading your post it is an impression that non-nitrox trained divers may reach. That said, 88 mins on a 12l? I'd be breathing that on the surface!!!!! Good posts guys and gals - nice and imformative. Lets see more of these techy questions being posted and answered.

Regards

[Mr T.]

Hey Heads,

Got to disagree there Bro! There are some basic (they have to be for me!) scientific reasons why I find Nitrox a better gas. You do not take as many breathes on Nitrox as you do on air - or rather you DO take the same amount but, beause the O2 mix is greater, you take them over a longer period of time - ergo extended bottom times.

Added to this is that before every dive (and some of you might also do this) I take three VERY deep breathes, nearly to the point of hyper-ventilating (but not quite!). I find that this 'air-iates' my lungs and the demand for air/breath is not so great on descent. This to start the dive then builds itself into the course of the dive where I have trained myself to breath VERY slowly, even when finning like man possessed into current.

Again, I'm by no means unique in this. It does tend to piss my wife off as I smoke a fair bit and she is always out of the water a good 20 to 30 mins before me on most dives. She doesn't smoke. Not that I'm advocating smoking - nasty, filthy habit!! ;)

Again, I can't explain it, I just know that Nitrox means I breath even more slowly again as it has a greater O2 content, meaning that every lung full of the richer mix gives me the sense of precisely what it says on the tin: "MORE O2" - therefore less surge for demand.

On the 88 mins dive, I was the last one in the water with the instructor. When I got to 65 Bar I signalled to him that we probably had about 15 mins left before we quit the water - he then showed me his gauge, it was at 26 Bar.

Assuming a dive doesn't go much below 30 metres, I will easily get a good hour in the water on a single 12L. A couple of weeks ago, they gave me the wrong tank for the 3rd dive of the day - it had 150 Bar in it; I was able to do 58 minutes (with safety stop) with a max bottom of 21 metres. Bearing in mind that this is in a wet suit and not a dry suit where you'd have to sort your buoyancy using the suit, which wastes gas.

Cheers,

[Jay]

Appreciate your personal circumstances Bren but IN GENERAL, it is the CO2 content in your lungs that triggers the breathing reflex - you could be breathing pure O2 and still feel the same need to breathe after 30 secs or more. The amount of O2 is immaterial. Having said that, I am a great believer in mental state as being a more primary drive to breathe (eg free divers constantly state that mental exercise enables them to conquer the physiological need to breathe - conversely, panic will make a diver want to over breathe his reg even though he is receiving more than he needs). I am NOT knocking your posts - I'm just pointing out that from a purely PHYSIOLOGICAL point of view (ie ignoring other factors), the amount of O2 in the mix should not affect a divers breathing reflex.

Regards

[Mr T.]

I think we can agree on the 'breathing reflex', what I'd search for, and maybe we need to ask Andy Hayhurst here, is empirical evidence one way or the other. Yes, no question the reflex gets triggered, but we're debating here about the regularity of same - the 'timed' spaces in between each breath become longer - for me a least - on Nitrox.

And no worries friend, I never took your counter-point as 'having a go' or indeed, 'knocking' my post. If I'm wrong I'll coff to it mate, as opposed to some one just throwing f*cks in to the mix and blathering.

[Jay]

Sounds good to me - always learning and as my nitrox course is PADI based there is always the 'lies to children' aspect to bring into the equation - ie "we'll tell the aproximate truth but not the whole truth, but at least you'll understand enough not to die!". I'd appreciate hearing from Andy just to add to my knowledge. (God, I love this forum - at least you can ask questions, have debates and not get slammed as a stroke out of hand)

[Ammers]

I love this forum too, it's most civilised.

Bren, could you show us some examples on this forum of what you described as

"If I'm wrong I'll coff to it mate, as opposed to some one just throwing f*cks in to the mix and blathering" - to my knowledge no one on the Yorkshire Diver's Forum swears at each other, can you point it out please so it can be stamped out.