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Scuba Forum / General / December 2004A few serious questions for Curtis or whoever.
When I got my tanks reinserted and thought about our upcoming dive where a cave is available to the trained or the foolish (I'll leave it to the reader to decide which, if either, I might be), a few questions occurred to me, ones I'm not likely to discover by accident and not interested enough to research for myself. So, I'll ask them here: 1. What's the difference between a stage bottle and a deco bottle? 2. What size bottle is normally, or most popularly, used as a stage bottle? 3. What size bottle is normally, or most popularly, used as a deco bottle? 4. When diving air, nitrox or Trimix and using a gas with a high oxygen percentage for deco, what's the "official" word on what level of O2 to use and at what depth(s). 5. Is there a hard copy table, or something similar, to allow one to understand changes to deco and repetitive dive group when using high levels of O2 for deco on an air, nitrox or trimix dive or do you simply accept that you're safer? 6. Are there non computerized tables, or combination of tables, that would allow you to understand the deco issues on a trimix dive. 7. What's the street price for a dive computer that will handle two gasses and allow the diver to change the gas setting manually during the dive? 8. What's wrong with such a computer for the recreational trimix diver? Lee > 1. What's the difference between a stage bottle and a deco bottle? A stage bottle has bottom gas in it and is used to extend your time/distance. Deco bottles are for deco, and are dropped at the MOD. > 2. What size bottle is normally, or most popularly, used as a stage bottle? Luxfer 80. > 3. What size bottle is normally, or most popularly, used as a deco bottle? In the ocean, Luxfer 40. In cave diving, I prefer the Luxfer 40 or 80. a lot of cave divers use steel 72's for their O2. > 4. When diving air, nitrox or Trimix and using a gas with a high oxygen > percentage for deco, what's the "official" word on what level of O2 to use > and at what depth(s). 50% at 70', O2 at 20' > 5. Is there a hard copy table, or something similar, to allow one to > understand changes to deco and repetitive dive group when using high levels > of O2 for deco on an air, nitrox or trimix dive or do you simply accept that > you're safer? You use a program like D plan. I have a table for O2 deco that was given to me by an old instructor, but I think it was generated with Dr X > 6. Are there non computerized tables, or combination of tables, that would > allow you to understand the deco issues on a trimix dive. Navy gas table, but it uses very high PO2's that are not suitable for us. > 7. What's the street price for a dive computer that will handle two gasses > and allow the diver to change the gas setting manually during the dive? Don't know. > 8. What's wrong with such a computer for the recreational trimix diver? I use D Plan to start with, but modify the schedule it gives based on experience. This is what most gas divers I know do. One of my buddies bought a thousand dollar trimix computer and only used it a few times, because it did not "allow" the schedule that works for him. Some answers from a different perspective:- >> 1. What's the difference between a stage bottle and a deco bottle? > >A stage bottle has bottom gas in it and is used to extend your >time/distance. Deco bottles are for deco, and are dropped at the MOD. We don't drop bottles. All divers carry all the bottles all the time. Unless you are in a cave and the way out is the way in. This way, any diver can ascend from any stage of the dive with, or without, a buddy. >> 2. What size bottle is normally, or most popularly, used as a stage bottle? Aluminium 12, 10, or 7 litres, depending on the depth, and the planned hang time, and the bale out plan. >> 3. What size bottle is normally, or most popularly, used as a deco bottle? > >In the ocean, Luxfer 40. In cave diving, I prefer the Luxfer 40 or 80. a >lot of cave divers use steel 72's for their O2. See answer 2. >> 4. When diving air, nitrox or Trimix and using a gas with a high oxygen >> percentage for deco, what's the "official" word on what level of O2 to use >> and at what depth(s). > >50% at 70', O2 at 20' Max PPO2 of 1.4 bar. >> 5. Is there a hard copy table, or something similar, to allow one to >> understand changes to deco and repetitive dive group when using high levels [quoted text clipped - 6 lines] >Navy gas table, but it uses very high PO2's that are not suitable for >us. Go to www.ddplan.com and play with some profiles and gasses. >> 7. What's the street price for a dive computer that will handle two gasses >> and allow the diver to change the gas setting manually during the dive? > >Don't know. Price? lots. Trimix or Nitrox or both? Explorer, VR3, and now some nitrox only units are available. One from Uwatec can reset all the tissue values between dives by inputting a 3 digit code. Bend it in the morning, reset and then dive in the afternoon as if nothing had happened....... Some rebreathers come with deco software already built in. >> 8. What's wrong with such a computer for the recreational trimix diver? > >I use D Plan to start with, but modify the schedule it gives based on >experience. This is what most gas divers I know do. One of my buddies >bought a thousand dollar trimix computer and only used it a few times, >because it did not "allow" the schedule that works for him. Is there such a thing a recreational trimix? If it became widely used would the incidence of bends increase? Stops and ascent rates are quite critical on Trimix, and I'm not sure the average muppet could do it. Byee Pete S. > Some answers from a different perspective:- > > [quoted text clipped - 6 lines] > Unless you are in a cave and the way out is the way in. This way, any > diver can ascend from any stage of the dive with, or without, a buddy. They were talking about caves. Allowing the "with or without a buddy" into your vocabulary is allowing the foot in the door. > >> 2. What size bottle is normally, or most popularly, used as a stage bottle? > > Aluminium 12, 10, or 7 litres, depending on the depth, and the planned > hang time, and the bale out plan. Lee lives in the US. > Max PPO2 of 1.4 bar. Depends. > Go to www.ddplan.com and play with some profiles and gasses. > Is there such a thing a recreational trimix? Never heard of anyone diving 21/40, 25/35 or 30/30? > If it became widely used would the incidence of bends increase? Stops and ascent rates are > quite critical on Trimix, and I'm not sure the average muppet could do it. Average muppet? Your paragraph above is an encapsulation of the reasons you should not be handing out "advice" on diving trimix. In a pinch, use Navy Tables (available online free with the entire manual), do the EAD math, swap the ten and 20 foot stops, and use the swapped 20 as ascent time from 20. I have several dive planning apps, Lee, ping me and I'll send you a couple. >> We don't drop bottles. All divers carry all the bottles all the time. >> Unless you are in a cave and the way out is the way in. This way, any >> diver can ascend from any stage of the dive with, or without, a buddy. > > They were talking about caves. I wasn't. > I have several dive planning apps, Lee, ping me and I'll send you a > couple. Later. I have a BBQ to go to now. > >> We don't drop bottles. All divers carry all the bottles all the time. > >> Unless you are in a cave and the way out is the way in. This way, any [quoted text clipped - 8 lines] > > Later. I have a BBQ to go to now. Yeah, we have a buffalo roast in the crock pot... >Allowing the "with or without a buddy" into your vocabulary is allowing the >foot in the door. Which foot in the door is that? Solo diving? Nothing wrong in that. >> >> 2. What size bottle is normally, or most popularly, used as a stage >bottle? [quoted text clipped - 3 lines] > >Lee lives in the US. I know. I'm sure he's bright enough to conert 232 bar 12 litre to cuft. And anyway, what do I know, I gave up stage and deco bottles 3 years ago. I now use one mix surface to surface. >> Max PPO2 of 1.4 bar. > >Depends. Yes, it depends. I did 2.8 for 7 hours once. No hits. >> Is there such a thing a recreational trimix? > >Never heard of anyone diving 21/40, 25/35 or 30/30? Yes, 21/40 is a fairly standard gas for 40 to 60m dives. Personally I use 20/50 @1.3 down to 50, and after that 10/50 or 10/70 @ 1.3. >> If it became widely used would the incidence of bends increase? Stops and >ascent rates are [quoted text clipped - 4 lines] >Your paragraph above is an encapsulation of the reasons you should not be >handing out "advice" on diving trimix. Please expand. All I was trying to do was indicate that the average "recreational" diver probably isn't ready for precise stops on a gas that is fast in and fast out. Pete S. > All I was trying to do was indicate that the average "recreational" > diver probably isn't ready for precise stops on a gas that is fast in > and fast out. With "most recreational profiles" (here is where we get into trouble; definitions vary), the issues of up to 40% helium in the mix have little or nothing to do with surfacing, '"recreational" in this context necessarily meaning nothing to stop you from a direct ascent to the surface at any point in your dive. The benefits of helium in the mix to me are reduced narcosis and reduced residual anesthetic effect. >> All I was trying to do was indicate that the average "recreational" >> diver probably isn't ready for precise stops on a gas that is fast in [quoted text clipped - 5 lines] >meaning nothing to stop you from a direct ascent to the surface at any point >in your dive. So you are talking obout "no stop" trimix? I think you will find you have short bottom times, and the ascent rates are a little more critical. Fast ascent on air or nitrox? Sit down and breath some O2. Fast ascent on trimix? Call a helicopter...... Trimix tends to be a trade off between narcosis, and how long you are prepared to hang around decompressing for. You commented in a previous post that trimix isn't rocket science. It isn't. It's easy to dive trimix. Breathe in, breathe out, breathe in, breathe out. Stop, wait. Stop, wait. Get back on the boat. But divers do need to be more precise in their diving skills. >The benefits of helium in the mix to me are reduced narcosis and reduced >residual anesthetic effect. Well on that point we agree. > The benefits of helium in the mix to me are reduced narcosis and reduced > residual anesthetic effect. That is a *benefit*? More cost, less narc... Doesn't seem like a benefit to me... <evil-grin> -- www.narcosis-republic.us > Which foot in the door is that? Solo diving? Nothing wrong in that. And that statement makes me suspect your abilities to give advice. Curtis > > Which foot in the door is that? Solo diving? Nothing wrong in that. > > And that statement makes me suspect your abilities to give advice. As a solo diver I can say I don't recommend the practice. >> > Which foot in the door is that? Solo diving? Nothing wrong in that. >> >> And that statement makes me suspect your abilities to give advice. > > As a solo diver I can say I don't recommend the practice. Right. I too have done it many many times and no one else should. > >> > Which foot in the door is that? Solo diving? Nothing wrong in that. > >> [quoted text clipped - 3 lines] > > > Right. I too have done it many many times and no one else should. Guess I forgot the smiley... >> Which foot in the door is that? Solo diving? Nothing wrong in that. > > And that statement makes me suspect your abilities to give advice. Why? Pete S. >>> Which foot in the door is that? Solo diving? Nothing wrong in that. me >> And that statement makes me suspect your abilities to give advice. > Why? If you really have to ask, you'll never understand, and I'm really not into singing lessons. Curtis > We don't drop bottles. All divers carry all the bottles all the time. > Unless you are in a cave and the way out is the way in. This way, any > diver can ascend from any stage of the dive with, or without, a buddy. We keep the deco bottles in the ocean. That's why we use Luxfer 40's - they swim well. > >50% at 70', O2 at 20' > > Max PPO2 of 1.4 bar. You need higher to properly decompress from a real gas dive. > Is there such a thing a recreational trimix? If it became widely used > would the incidence of bends increase? Stops and ascent rates are > quite critical on Trimix, and I'm not sure the average muppet could do > it. There are some groups who use recreational trimix, without carrying deco gas. It's not rocket science, but the agencies have a vested interest in making it seem like it is. A reasonably intelligent monkey could be taught to use mixes <40% helium in a few minutes. > A reasonably intelligent monkey could be > taught to use mixes <40% helium in a few minutes. After all, look at you and I. >> Max PPO2 of 1.4 bar. > > You need higher to properly decompress from a real gas dive. You're going to have to define "properly" if you're going to defend this one. You can certainly decompress quicker with a higher PPO2 than with a lower one, but I'm reasonably certain that there's a whole range of combinations that will get you to the surface in healthy condition. Lee >>> Max PPO2 of 1.4 bar. >> >> You need higher to properly decompress from a real gas dive. The question was about bottom gas. >You're going to have to define "properly" if you're going to defend this >one. You can certainly decompress quicker with a higher PPO2 than with a >lower one, but I'm reasonably certain that there's a whole range of >combinations that will get you to the surface in healthy condition. Talk to any of the training agencies. The 1.4 limit is a bottom gas restriction. The restriction for deco gas is 1.6. The reason I choose to use 1.3 throughout the dive is because NOAA tables permit 1.3 for 3 hours per day, every day. So, if you are doing a 90m (300ft) dive every day for a week, Ox Tox ceases to be an issue. There are other issues though! By "properly" do you mean rapidly? Are you one of the divers that says "my tables/computer are better than yours because I got back on the boat quicker". As Lee said, there are many combinations of gasses that will get you to the surface safely. You could even deco safely on 18/82 heliox if you wanted to. But it may take some time! Pete S. >>>> Max PPO2 of 1.4 bar. >>> >>> You need higher to properly decompress from a real gas dive. > > The question was about bottom gas. Actually, the question was too generic for what the discussion has become. >>You're going to have to define "properly" if you're going to defend this >>one. You can certainly decompress quicker with a higher PPO2 than with a [quoted text clipped - 3 lines] > Talk to any of the training agencies. The 1.4 limit is a bottom gas > restriction. The restriction for deco gas is 1.6. Sort of agreed. My training set a 1.5 limit for relaxed diving, 1.4 for strenuous diving and 1.6 for no effort diving such as deco is presumed to be. Of course deco can't be counted on to be no effort for every dive. As far as I know, there's nothing that requires you to use the highest permissable PPO2 for deco. While it may speed decompression, I think it's pretty valid to chose a slightly lower O2 risk at the expense of longer deco, at least up to a point. That's why I suggested the term "properly" be defined. I think Al's presumption is that "properly" means as rapidly as possible consistent with safety. Mine might differ, that is, it might if I was qualified to have an meaningful opinion of my own. Lee > Talk to any of the training agencies. The 1.4 limit is a bottom gas > restriction. The restriction for deco gas is 1.6. Which is, of course, totally bass-ackwards. While there is a cause-effect between work and nitrogen narcosis, there is none between work and oxtox. So a ten foot error at, say 230 fsw, is far less serious in terms of PPO2 exposure than a ten foot error on deco O2. Yet you deco closer to the limits. Hmmmmmmmm. >> Talk to any of the training agencies. The 1.4 limit is a bottom gas >> restriction. The restriction for deco gas is 1.6. [quoted text clipped - 3 lines] >While there is a cause-effect between work and nitrogen narcosis, there >is none between work and oxtox. Yes there is. That's why the limit is set at 1.4 for depth and 1.6 for deco. Of course, limit vary from person to person, and navies go higher, but 1.4 / 1.6 seems to be good for most people. As I stated in an earlier post, I've done 2.8 for 7 hours without a hit, but my workrate at the time was zero. Pete S. >>> Talk to any of the training agencies. The 1.4 limit is a bottom gas >>> restriction. The restriction for deco gas is 1.6. [quoted text clipped - 9 lines] > an earlier post, I've done 2.8 for 7 hours without a hit, but my > workrate at the time was zero. There is no direct cause-effect relationship. There is a substantial indirect relationship, ie the increased risk of oxtox as CO2 inspiration increases, as has been observed and understood for almost a century, leading to recirculators being universally adopted in the late '30s. The mechanisms are explained by Vann & Natoli. In closed dress trimix diving, the suit must be flushed with 100% O2 before starting O2 deco, to eliminate all CO2. The rec trimix user, with a reg stuck in his mouth, is prolly at greater risk of CO2 inspiration while at deco, reading a book and shallow breathing. It's bass-ackwards. The specific numbers, 1.4 and 1.6, are totally arbitrary, pulled out of someone's a.s, with absolutely no meaning except that a drunk, stoned, incompetent diver will have to really screw up to exceed his actual limits. It's 1.4 or 1.6 for exactly the same reason that speed limits on rural interstates are 65 or 70: it keeps most of the idiots under 150. >> Talk to any of the training agencies. The 1.4 limit is a bottom gas >> restriction. The restriction for deco gas is 1.6. [quoted text clipped - 7 lines] > > Hmmmmmmmm. This is not what I was taught. Lee > By "properly" do you mean rapidly? Are you one of the divers that says > "my tables/computer are better than yours because I got back on the > boat quicker". As Lee said, there are many combinations of gasses that > will get you to the surface safely. You could even deco safely on > 18/82 heliox if you wanted to. But it may take some time! Decompression is something we can argue about forever. The goal of decompression is to decompress. When you decompress properly, you feel good, ready to dive again or for another activity. It's different for everyone, and I've found what works for me has some things in common with what works for the people I've learned from, although many of them do less deco than I do. I've tried the deco strategies that use lower PO2's, and I felt miserable afterwards. The time at 70 and 20 ft with a PO2 of 1.6 absolutely makes me feel better, and I consider it to be very important. It is very important to toggle the O2 with something less rich (I use backgas, and know the argument against that)to effectively offgas. I've used this strategy to do up to 4 deep gas dives a day in some very remote areas. YMMV. al >>> Max PPO2 of 1.4 bar. >> >> You need higher to properly decompress from a real gas dive. > >You're going to have to define "properly" if you're going to defend this WTF? You asked for answers to questions! Al need "defend" nothing. He knows. You don't. Any more questions? safe diving, bullshark >>>> Max PPO2 of 1.4 bar. >>> [quoted text clipped - 11 lines] > > Any more questions? Several: Who pissed on your parade? Did you add anything except criticise of others? What makes you think you have the right, let alone the obligation to decide what Al and I have to say to one another or what he has to define in order to defend a position? Any more comments? Lee >Subject: Re: A few serious questions for Curtis or whoever. >From: bullshark >>>> Max PPO2 of 1.4 bar. >>> [quoted text clipped - 11 lines] > >Any more questions? Jammer's going to be pissed that you're doing his act. :-) Capt. Bill Thanks, Al > A stage bottle has bottom gas in it and is used to extend your > time/distance. Deco bottles are for deco, and are dropped at the MOD. I'm not loaning you any of my tanks for open water diving. You'll drop them all on your way up. <grin> > In the ocean, Luxfer 40. I guess a 30 is unpopularly small, yes? You have stock in Luxfer? Personally, I'd look for a way not to use their tanks. I've got quite a few Catalinas and PSTs, but only one Luxfer. Interestingly, it's an 80 O2 tank. Yes, it's properly marked. >> 4. When diving air, nitrox or Trimix and using a gas with a high oxygen >> percentage for deco, what's the "official" word on what level of O2 to >> use >> and at what depth(s). > 50% at 70', O2 at 20' OK, that's O2 at 20 for me, at least for now. Actually, I'm gunshy enough about CNS toxicity that I'd probably stick with a slightly lower PPO2, either by using it shallower or using a lighter mix. >> 5. Is there a hard copy table, or something similar, to allow one to >> understand changes to deco and repetitive dive group when using high [quoted text clipped - 5 lines] > You use a program like D plan. I have a table for O2 deco that was given > to me by an old instructor, but I think it was generated with Dr X No fun. I know there are computer programs out there. My interest is more academic than practical. I learn more about why I should trust some computer program by using tables. >> 6. Are there non computerized tables, or combination of tables, that >> would >> allow you to understand the deco issues on a trimix dive. > > Navy gas table, but it uses very high PO2's that are not suitable for > us. Thanks, I'll look them up. Learning's always worth some effort. >> 8. What's wrong with such a computer for the recreational trimix diver? > > I use D Plan to start with, but modify the schedule it gives based on > experience. This is what most gas divers I know do. One of my buddies > bought a thousand dollar trimix computer and only used it a few times, > because it did not "allow" the schedule that works for him. More to study. I'm not sure I'll ever do any gas diving, let alone enough to warrant a computer. Still, it would seem that a computer would be as good for a multilevel gas diver as it is for a multilevel air or nitrox diver. Since any deep or mix diving I ever do will almost certainly be in open water, on wrecks or deep walls, planning on the fly still has a strong appeal. At any rate, thanks for the response. Lee > I guess a 30 is unpopularly small, yes? You have stock in Luxfer? > Personally, I'd look for a way not to use their tanks. I've got quite a few > Catalinas and PSTs, but only one Luxfer. Interestingly, it's an 80 O2 > tank. Yes, it's properly marked. A 30 is too small for your 70' gas, but is ok for O2. I like the 40's because they swim better. Catalina tanks suck for sling tanks (stages or deco). They are bottom heavy and don't swim well. Somewhere I've got some pictures that Mark Zurl took of me with Catalina 40's and Luxfer 40's, and it is very plain to see. I'll look for them later. > A 30 is too small for your 70' gas, but is ok for O2. I like the 40's > because they swim better. I looked at both today. The 30 appeared to be about the same diameter as the 40, but noticably shorter. I don't see why that one would swim better than the other and, if I were to guess, I would have guessed that the 30 would be easier to deal with. Why isn't it? > Catalina tanks suck for sling tanks (stages or deco). They are bottom > heavy and don't swim well. Somewhere I've got some pictures that Mark > Zurl took of me with Catalina 40's and Luxfer 40's, and it is very plain > to see. I'll look for them later. I can't speak for all Catalinas or all Luxfers. I use 3300 psi Catalina Compact 80s. They seem pretty balanced to me. In fact, the comparable Luxfer neutral buoyant tanks are reported to be quite bottom heavy themselves, but I've never compared comparable models. I used to have standard Catalina 80s and I don't recall them being different from the same model Luxfer tanks, but, to be honest, I probably would not have noticed back then. I was just happy to be wet. Lee > > A 30 is too small for your 70' gas, but is ok for O2. I like the 40's > > because they swim better. [quoted text clipped - 3 lines] > than the other and, if I were to guess, I would have guessed that the 30 > would be easier to deal with. Why isn't it? Try them both, then get back to us. > I looked at both today. The 30 appeared to be about the same diameter as > the 40, but noticably shorter. I don't see why that one would swim better > than the other and, if I were to guess, I would have guessed that the 30 > would be easier to deal with. Why isn't it? I consider the Luxfer 30 to be a perfectly acceptable deco bottle, and sometimes use one for my O2. The 40 does swim slightly better though. It is longer, and the buoyancy at the bottom helps with balance and trim when using steel doubles (it has a longer "lever" between the center of buoyancy and the attachment point on the hip). The Catalina 30 is like a rock, and the 40 isn't much better. I have owned both, and sold the Cats. > > 50% at 70', O2 at 20' > > OK, that's O2 at 20 for me, at least for now. Actually, I'm gunshy > enough about CNS toxicity that I'd probably stick with a slightly lower > PPO2, either by using it shallower or using a lighter mix. If you do that and change the lower mix from 50% or the usual resting deco PPO2 of 1.6 you will just extend the stop time so no problem However the 100% should be kept even if you change the stop depth to change the PPO2. The other thing is that few people do more than 2 mix dives a day so the CNS toxicity risks are reduced. > >> 5. Is there a hard copy table, or something similar, to allow one to > >> understand changes to deco and repetitive dive group when using high [quoted text clipped - 7 lines] > more academic than practical. I learn more about why I should trust > some computer program by using tables. All/most/ computer programs produce tables. Good tables as you know are not magic they have been made by taking dives that work, dives that didn't adding some safety/fudge factor and printing the results. Good computer programs function in much the same way, so there is little difference between them. I know I have left out the research etc. that produced the successful dives but the principal is true The problems with producing tables for Extended range/mix diving is that you have so many variables and the theory is still developing so that they quickly need to be redone if they are to keep current. If you really want to check out some tables the IANTD Technical Diver Encyclopedia has about 90 pages of tables published in 1998, some of the information is out of date but most is not. It is also a good starting point for understanding some of the detail. Much of it you will know but there is enough to make it a reasonable book to get and keep. There is a good page at <http://www.Inspired-Training.com/deco_comparisons.htm> The dive program that I learned on is DecoPlanner and that seems to give safe profiles. it is not difficult to use. gives interesting tissue saturation graphs, and comes from GUE That may be a good or bad point.;-) > >> 6. Are there non computerized tables, or combination of tables, that > >> would allow you to understand the deco issues on a trimix dive. [quoted text clipped - 15 lines] > would be as good for a multilevel gas diver as it is for a multilevel > air or nitrox diver. Mix diving and really deep diving is a much less understood and computer SW for it is less tested. it introduces the chance of counter diffusion DCI and that can give you a DCI hit at significant depth. Up to date there few SW programs that are really good, even fewer that are good for deeper, 100m+ depths. There are also some that are really bad as Mark Ellyatt proved on his 260M dive last year. All this means that with the current computers while they may be OK for shallower depths may not be so great for others. > Since any deep or mix diving I ever do will almost > certainly be in open water, on wrecks or deep walls, planning on the fly > still has a strong appeal. I well understand the appeal, but unless diving CCR, which gives really big effective gas reserves, and using deco/bailout tanks that are much bigger than needed, planning on the fly (as opposed to changing to a different planed profile) has great risks. > At any rate, thanks for the response. > > Lee >replace spamblock with my family name to e-mail me >> 6. Are there non computerized tables, or combination of tables, that would >> allow you to understand the deco issues on a trimix dive. > > Navy gas table, but it uses very high PO2's that are not suitable for > us. It's not that the Navy tables (even the early ones) are not conservative, it's that the recreational tables are ultra-conservative. > It's not that the Navy tables (even the early ones) are not > conservative, it's that the recreational tables are ultra-conservative. The Navy gas tables are for guys in hats on a stage who finish decompressing in a chamber. They go to O2 at 50 ft for 10 minutes before being yanked into a nice dry chamber. >> It's not that the Navy tables (even the early ones) are not >> conservative, it's that the recreational tables are ultra-conservative. > > The Navy gas tables are for guys in hats on a stage who finish > decompressing in a chamber. They go to O2 at 50 ft for 10 minutes before > being yanked into a nice dry chamber. There are a lot of equipment and procedure issues, such as you mention plus use of recirculators and heated underwear. Nevertheless, the recreational trimix tables (and algorithms) are ultra-conservative. >Subject: Re: A few serious questions for Curtis or whoever. >From: Al Wells al.wells@gmail.com >> 8. What's wrong with such a computer for the recreational trimix diver? > >I use D Plan to start with, This is what most gas divers I know do. One of my buddies >bought a thousand dollar trimix computer and only used it a few times, >because it did not "allow" the schedule that works for him. >but modify the schedule it gives based on >experience. I don't understand how you could know how much you can modify your schedule without getting bent? Is this done by the seat of your pants? Do people just modify their deco schedule till they get a hit? ;-) How do you know when you've close to going to far? Do you use doppler testing and back down on you deco planning as you find the bubbles building up? Capt. Bill > I don't understand how you could know how much you can modify your schedule > without getting bent? you do it in small steps. There's a pretty big range of feel better/not feel better. > Is this done by the seat of your pants? There is some science to it. > How do you know when you've close to going to far? The goal is always to feel better, not to get out faster. > Do you use doppler testing and back down on you deco planning as you find the > bubbles building up? This was done by others, and we use what they found as a guideline. >Subject: Re: A few serious questions for Curtis or whoever. >From: Al Wells al.wells@gmail.com >> I don't understand how you could know how much you can modify your schedule >> without getting bent? [quoted text clipped - 15 lines] > >This was done by others, and we use what they found as a guideline. Thanks for the enlightenment. Capt. Bill > When I got my tanks reinserted ?? >and thought about our upcoming dive where a > cave is available to the trained or the foolish (I'll leave it to the reader [quoted text clipped - 16 lines] > and allow the diver to change the gas setting manually during the dive? > 8. What's wrong with such a computer for the recreational trimix diver? Well, hmm, if that doesn't cure my insomnia, maybe I'll go read the dictionary or something. :^) Love ya. Have fun at dinner. Give a big hug to Jayna for me. And see if you can't stop Curtis from throwning Greg on the BBQ, K? >> When I got my tanks reinserted Bad spelling and a spellchecker. Make it reinspected. Lee > 7. What's the street price for a dive computer that will handle two gasses > and allow the diver to change the gas setting manually during the dive? http://www.vr3.co.uk/vr3/main.php?content=intro About $1,250 street price. I believe the Suunto Vytek will also allow gas switches underwater, but I don't know for sure. > 8. What's wrong with such a computer for the recreational trimix diver? I'm not going to touch this one. > Lee > When I got my tanks reinserted and thought about our upcoming dive where a > cave is available to the trained or the foolish (I'll leave it to the > reader to decide which, if either, I might be), a few questions occurred > to me, ones I'm not likely to discover by accident and not interested > enough to research for myself. So, I'll ask them here: Note: on the cave, it's closed for this dive. :-) > 1. What's the difference between a stage bottle and a deco bottle? > 2. What size bottle is normally, or most popularly, used as a stage > bottle? > 3. What size bottle is normally, or most popularly, used as a deco bottle? Al Wells has it covered well. > 4. When diving air, nitrox or Trimix and using a gas with a high oxygen > percentage for deco, what's the "official" word on what level of O2 to use [quoted text clipped - 8 lines] > and allow the diver to change the gas setting manually during the dive? > 8. What's wrong with such a computer for the recreational trimix diver? Best answered by someone beyond my experience. Curtis Thanks Goodness for some dive talk here, the Nasty Republicans have again slapped the crap out of anything On Topic. Well, let's see: when I took my dive classes and got certified (PADI and Y) inthe mid-70's, mix schedules were published in our training books. Have you lost yours? When I was first introduced to scuba by a YMCA instructor, in 1962, I didn't get a book. As I recall, there wasn't a PADI to get a book from back then. When I got my first certification card, from NAUI in 1969, I got a book, but I'm afraid it didn't survive the years. I don't know precisely when I lost it, but I'm pretty sure it was before you got yours. I don't recall any schedules in the book and, to be honest, I don't remember the tables we used particularly well either. I can't remember if they were plastic or paper. At present, I have at least three sets of tables and probably more. To the best of my knowledge, none of them are for mix, but the ones in my copy of the Navy Dive Manual may be. I'll have to look. Lee > Thanks Goodness for some dive talk here, the Nasty Republicans have > again slapped the crap out of anything On Topic. Well, let's see: when I > took my dive classes and got certified (PADI and Y) inthe mid-70's, mix > schedules were published in our training books. Have you lost yours? You up? Call my cell. Curtis I wasn't, but I am. You still up? Lee  Signature__________________________________________ If I got smart with you, how would you know? > > You up? Call my cell. > > Curtis >I wasn't, but I am. You still up? Yep, for a few more minutes. I'm all packed, truck is full, and very ass-heavy. 12 tanks total, 7 for me, 5 getting dropped off.. :-) Curtis >>I wasn't, but I am. You still up? > > Yep, for a few more minutes. Gonna meet Grumman in about 6 hours to do a couple of warm-up dives with single 80s, then head for Ocala. Plan on camping out, so should be able to sleep well tonight, and be quite fresh for Monday. Have 2 sets of dub AL80s ready for Monday, good for 2 long dives, and will top off for a third if we go 3. No room for my dub 125s, nor any real need. Curtis >>>I wasn't, but I am. You still up? >> [quoted text clipped - 5 lines] > AL80s ready for Monday, good for 2 long dives, and will top off for a > third if we go 3. No room for my dub 125s, nor any real need. You'll probably get this after you return, but what the heck. After Jayna gets up, I'll check on the boat one more time and head up to Pompano. I put it in day before yesterday and there's water in the bottom today that can't be accounted for by rain. I may have to get a mechanic on it and I absolutely will ensure the batteries are charged and the bilge pumps working. A mechanic will be working on my generator while I'm diving in Ocala. There's a marine fleamarket in Pompano that Dave's helping a friend with. It shuts down at 3:00 PM and we'll be leaving from Pompano as soon after he helps the friend break everything down as possible. I'll chip in to try to speed the process. We'll be in Homosassa tonight and Ocala on Monday morning. Dave and I will both be using my PST 100s with 32%. What's Grumman using, do you know? Have you heard from Nightspark? He mentioned the possibility of some Florida diving too. Lee > Have you heard from Nightspark? He mentioned the possibility of some > Florida diving too. We had dinner Friday night. He dove Friday morning and was supposed to go out yesterday morning and possibly this morning. I saw a couple dive boats from the comfort of my hotel room today. It was a bit choppy but not as bad as had been predicted. I should have brought my gear. > We had dinner Friday night. He dove Friday morning and was supposed > to go out yesterday morning and possibly this morning. I saw a couple > dive boats from the comfort of my hotel room today. It was a bit > choppy but not as bad as had been predicted. I should have brought my > gear. And you should have driven north. We had barbecued pig & chicken tonight instead of the planned meal, but nobody seemed to think they missed anything. Curtis > I should have brought my gear. Of course... Then you could have nearly stepped on a manatee also... > Gonna meet Grumman in about 6 hours to do a couple of warm-up dives with > single 80s Well, at least we *planned* on making them single 80s... <grin> An interesting impromtu design session... <grin |
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