View Full Version : Confused about the SMG course
Hi all,
I've nearly completed the bsac sports mixed gas course, (just got the open water dives left to do), and i've run into a problem.
I'm planning a dive to 57m and was calcualting what mix to use. Now this course allows me to use a mix with >= 20% o2 which is fine, but also <= 30% h2. With this 20/30 mix my END is 32m. The SMG manual says to keep the END to 30m or less preferably, OK it doesn't say "you have to keep it 30m or less" but I was wondering why I'm not allowed to use upto 35% helium so that a 60m (deepest i'm allowed to go) dive would also give me a END of 30m.
Any ideas? It just seems abit silly to me to not allow upto 35% h2. Obviously i'm guessing there must be some reason for this that willl require further training i.e the hypoxic mixed gas course, but i'm just curious.
Cheers
Phil
Dunny
The Sports mix courses (50m & 60m ) are basically twin set with ONE stage.
So you are using back gas & one decompression gas.
It becomes a point of logistics. If you keep the helium lean enough, it is feasible to complete the decompression on the back gas in the event of a total loss of decompression gas. If the Helium is too rich you will runout of back gas prior to completing the decompression.
When you do the Hypoxic course, then you are carrying TWO stage cylinders of DIFFERENT decompression gases. If you loose ONE of the stage cylinders, you should have planned the dive so that you can exit on back gas & ONE cylinder of ETHIER of the decompression gases.
The standard BSAC Hypoxic course is limited to 80m. The reason for this is that it is hoped that it will ensure that the diver could complete the dive plan as stated above. However, as you get deeper you reach the point where any loss of decompression gas becomes catastrophic .i.e. without assistance you cannot safely complete the dive. This is the point where you start to need standby divers, additional surface & inwater support & large amounts of gas available. This is the point where the next BSAC course takes over EXPEDITION TRIMIX.
I hope that clarifys things.
From a planning point of view, you as the diver have to be happy that you will be able to function properly & rationally at the END that a 30% He will give you at 60m (or 57m), if not then you limit the dive depth, so that you stay within your safe END!
Best of luck with the rest of the course (the hardwork starts on the dives!)
Gareth
hmm, the way we have been doing it is when the stages are not large enough for the gas requirements with the rule of halfs, then we have doubled up and taken two 7's with us. But admittedly both with the same mix.
Funnily though I just planned the 57m dive without deco gas and got a runtime of 166 minutes from proplanner with 20/30 mix and 0% safety factor!
I think I should buy that license for V-Planner quite soon!!
Phil
Dunny
OK if you are carrying two 7's is a much better idea at this kind of depth rather than one cylinder. You can afford to plan a loss of deco from one cylinder, In theory, you 'should' be able to complete the dive on the one deco cylinder (rules of 50). If it was me I would plan for the deco gas to runout at 75% of the gas in the cylinder, (requiring you to switch back to back gas to complete the decompression), of course there is no problem if you are still with your buddy because you can swap your empty cylinder for his half used one (an exercise you will be doing during the diving), however if you have seperated & are on your own on your DSMB rather than the shot, you don't have this luxuary!
You should have plans for gas loss, over run on time, over run on depth, if you overshoot the depth you deserve to fail , at this level you should never overshoot depth!
This is a lot better than relying on one deco cylinder, as you can see from your own calculations.
One other point, V planner, if it produces a significantly short runtime, are you happy with that!
If I said I have a table for air that allowed you to do 40 minutes to 40 meters no stop, would you be happy to follow it based on your experience, & the deco algorithom you have been previously using?
Gareth
My experience when switching from DDPlan to V-Planner was that V-Planner does not give any reduction is overall run time. I generally run it on VPM B/E with a +2 safety and for 25min bottom time 65m dives gives a longer runtime then 20/80 did. Never used proplanner, so can't comment on this program.
Cheers,
G
Dunny
I should clarify one point, the SMG course is ONE decompression mix, not one deco cylinder.
Gareth
I was just speaking to a friend who is running the couse with me and he said that the course has been changed from that which is in the student notes. He now said I'm allowed to use >= 18% 02 and <= 35 h2. This would make more sense to me. Can anyone confirm this?
Cheers
Phil
Dunny
I'll check, however they have just started printing the NEW cards, my SMG instructor card still qoutes minimum O2 = 20%, max He 30%.
Gareth
(MSI002)
Dunny
Just checked with HQ
SMG Course
There are two course formats
Recreatioal Trimix
Max Depth 50m
Gas 20/30
Normoxic Trimix
Max Depth 60m
Gas 18/35
Advanced Mixed Gas
Also known as Hypoxic Trimix
Max Depth 80m
Gas - Mixed Gas (not prescriptive)
Sorry for the confusion. This does mean you will need to recalculate your gases :), based on this.
Gareth
Thanks for that Gareth, that makes more sense to me now. Yes I will have to do the plans again but suppose with all this practice I'll be able to do it like its 2nd nature soon :p :p
Cheers
Phil
Nigel Hewitt
17-06-2008, 12:44
Deviating a bit from the thread but the questions seem answered... can somebody explain the differences between
Recreational Trimix
Max Depth 50m
Gas 20/30
Normoxic Trimix
Max Depth 60m
Gas 18/35
I can see a huge difference between Normoxic and Hypoxic courses with the idea that you now have a mix that can kill you if you're too shallow to add to the one that can kill you if you're too deep but I'm a bit perplexed what different skills you need between 20/30 and 18/35.
I may be having a blonde moment or missing something obvious as all my 'mix courses have been on CCR so explain slowly.
Garry Whyke
17-06-2008, 12:59
During the SMG rec course all the skills etc. are with a single stage.
The nomoxic qual adds a second stage, building in the need for a bit more kit config and getting balance / comfortable with twin stages.
In practice this is only 1 extra dive over and above the rec course (assuming all goes well).
To be honest I haven't come across anyone who just wanted to do the rec course yet. Everyone I have spoken to have been focussed on the Nomoxic (i.e. 60 mtr ticket).
Not too sure if the Nomoxic can be done in a similar timeframe as the Rec by adding the extra stage earlier or not (too much too soon??)? Could be worth considering though.
Cheers
................ Garry
MSutcliffe
17-06-2008, 13:17
Deviating a bit from the thread but the questions seem answered... can somebody explain the differences between
I can see a huge difference between Normoxic and Hypoxic courses with the idea that you now have a mix that can kill you if you're too shallow to add to the one that can kill you if you're too deep but I'm a bit perplexed what different skills you need between 20/30 and 18/35.
I may be having a blonde moment or missing something obvious as all my 'mix courses have been on CCR so explain slowly.
18% O2 will not kill the healthy individual at the surface. Come to that, 16% O2 will not kill you at the surface either.
hang on a minute - 10% O2 - well, that will also not kill a healthy individual at the surface, however, you will feel dreadful for a while, until your body starts to get you breathing an awful lot faster than normal to get enough O2 into your tissues.
Of course, if you are a respiratory cripple, or have significant ischaemic heart disease, then you may be killed by 18% O2 at the surface, but then you may also be killed by 21% O2 at the surface, and if you stress your already ischaemic heart enough, then you may die despite 100% O2 at the surface! You may get some angina pain if your heart disease is that bad, but some folk do not get pain - they just have a sudden and unexpected heart attack. It is a balance of risk, which you should educate yourself about before going off using hypoxic mixes.
The cut offs are, to a some extent, abritrary and artificial - but you have to put a cut off somewhere. IMHO - scrap the 'recreational' syllabus, and just have the one single 'normoxic' syllabus.
I may be having a blonde moment or missing something obvious as all my 'mix courses have been on CCR so explain slowly.
60m in a two stage dive on OC. 50m need not be.
Janos
Recreational trimix kind of replaces ERD.
Or rather, dependent on where you consider the cut off for air diving, 35m 32% or 42m 27%, you can can dive with 30 to 35m narcotic depth in the 40-50m zone.
So, by preference, I would rather teach Recreational Trimix than ERD (deep air).
It also allows an instructor to qualify a diver at rec mix rather than Normoxic if the student is borderline.
Gareth
If recreational trimix replaces the ERD then howcome the ERD is an entry requirement for the course?
Phil
If recreational trimix replaces the ERD then howcome the ERD is an entry requirement for the course?
Phil
You are corrrect. I did say 'kind of'.
There is a push away from deeper air diving. i.e. there is a preference to keep the END to 30m or less.
Due to the low He, the runtimes are not horrendously dissimliar to air, so there is a considerable advantage to pushing on to Rec' Mix.
The current ERD course is being re written as a feeder to the Rec' mix course. i.e more as a twinset course, although I haven't seen the new course materials yet.
The Advanced Nitrox course is also due for a new release this year.
This will mean that the BSAC will have a complete suite of current uptodate technical courses, that are all complementary.
Gareth
This will mean that the BSAC will have a complete suite of current uptodate technical courses, that are all complementary.
Gareth
And about time too I here lots of people say :p
Ah im off this weekend for SMG so it’s been really interesting to read all your post's
1. I have purchased V Planner licence put in safety factor of +5 and ran some Plans; I will be interested to see how these compare to Pro Planner
2. somewhere the comment about only coming across people aiming for 60M ticket I agree that’s my aim ( once I feel comfortable)
3. I thought ERD was in fact one of the best Courses I had been on if its being improved it can only (I hope) be even better and more recommended i guess not everyone will want to move to Mixed gas but at the least if ERD is replaced those people attending will have a better understanding of Mixed gas diving.
Finished the course this weekend, I have got to say that you have something good to look forward to it was brilliant!!
Proplanner and V-Planner have a very big difference in decompression obligations but thats what they ask you to use for the exam anyway!
Phil
Dunny
Glad you enjoyed the course, & that you thought it was both chalenging & informative.
It would be helpful for others if you could give a short writeup & post it.
Gareth
Well i'm in the middle of writing quite a long write up for my own site to do with diving, when its finished i'll copy it here.
Phil
Ok this is a long one! Taken from my site (http://phildonegan.co.uk)
Well for my 21st birthday present I asked if my mum and dad would pay for me to go and do a normoxic trimix course. They agreed so I asked around at my local dive club to see if anyone else fancied to do it with me. The people interested were myself, Joe and Steve. Paul also wanted to come along but just to the open water dives as he had started the course in the previous year but never finished it.
The training dives
The course started at the beginning of June with the drills and skills at Eccelston Delph. Steve had to drop out before this which just left me and Joe doing the drills. This was a wakeup call for me, as for the first time since i've been diving I was really struggling with the drills and also the amount of task loading which was upon me. Anyway we both managed to complete the drills but were ready for a good telling off from Dennis (our instuctor) when we got out. However Dennis did not tell us off, he knew it was our first proper dive using stages since this was a combined ERD and Normoxic course so he was quite forgiving but told us we needed to practice before the open water dives in chepstow in two weeks time.
Before the open water dives me and Joe did another three 1 hour long dives in Eccleston Delph just practicing the drills, this made a huge difference in my comfort factor with this type of diving as by the time of the last training dive the drills were now much easier and almost second nature.
The Open Water Dives
On Thursday evening myself, joe and paul all headed down to chepstow. The roads were fairly clear and we made good time in getting there. We checked into the Huntsman were our rooms were. We threw the bags into the rooms and went downstairs into bar were we had a few beers and started discussing the dives that would be ahead of us in the next few days. After a few we all turned in for an early night in anticipation of the diving the next day
Day 1, Dive 1
We met Dennis at the quarry at 9am he was already there waiting for us. We were briefed on what the dives would be over the next two days and what we would be doing on these dives. The first dive was to a maximum depth of 45m, so we got out the deco software and started finding out the ascent plan for the various plans that we needed. After this Dennis checked them over and was happy with what we came up with. So we put the mountains of kit together and loaded it into the van to be taken down the slipway to the pontoons below. A great thing about chepstow is that they have lots of trolleys around for divers to use to put there kit on and then haul it down the pontoons. This saves some of the back ache of having to carry about 60~80 kg of eqiupment.
On the pontoon we had our final brief and learnt of a new objective in the dive. Our instructor had lost his smb and reel a few weeks ago as it had fell down a hole but was just out of his reach so he asked me with my long arms (I'm 6ft 4in so I have a quite long arms) if i would mind having ago at getting it. With the final brief over we kitted up and did our buddy checks while laughing like idiots at the trimix playing with our vocal chords (boys will be boys). We jumped in and descended to 6m were we did a bubble check before descending to 45m. We found the hole were the smb was and seen it but it was also out of my reach too, bugger. Anyway we gave up on the SMB for now and carried on with the dive.
About 10 minutes into the dive Pauls regulator developed a fault and the dive had to be aborted (45m isn't a nice place when you have a faulty reg), we used the 1/2 time plan we had devised and came up without any problems. Upon inspection of Pauls reg there was a fork that was bent, (i'm no service technican so thats all i can say!).
Luckily the purpose of this dive was to simply practice using run times and also practicing the ascent rates which are very important so even though it was aborted the dives goal was still completed. After the dive we all debriefed and then started planning the next dive to 35m. This involved working out another three ascent plan incase anything went wrong etc.
Day 1, Dive 2
On this dive one of us would be leading it with the goal simply being a sucessful dive and ascending on DSMB's. When the ascent plan was completed we would then complete some drills at 6m.
So we started the dive again with a brief and then buddy check, Joe decided to lead the dive as i didn't feel comfortable with the ascent rates at this time. We then made the splash and descended to 6m for a bubble check. All was ok so we dropped down, this time we would not hit the bottom so it would be entirely mid water diving. As we got to our maximum depth we started swimming along the wall, this time again Pauls reg developed a problem. However we had already passed beyond the 1/2 time plan so we ascended to our first stop and waited for the run times to match up with were we were supposed to be. We exited the water after 39 minutes but a little cold and not to happy at this point as two dives had now been aborted, but these things happen.
We left our tanks to be filled at chepstow with our mix of 18/35 for the big dive the day after, and the anticipation and excitement I had for it was amazing!
Day 2, Dive 1, The BIG One
I woke up at 7.30am, now this was a surprise to me as I've been a student at Salford University for the past three years and i was unaware of there being a 7.30 in the morning, oh well i manged it anyway. We arrived at the site for just after 8.15am and went to collect our cylinders. My mix of 18/35 with a 60% nitrox stage came to a grand total of £52, lovely...
Paul managed to hire some new mares regs to use on this deep dive as he was losing faith in his kit at this point, this allowed him to dive as he was unlikely to do the 60m dive with a reg that was giving him problems. This then meant though that Paul needed to have his cylinder filled with the correct mix, unfortunatly this process takes about an hour to do so we were put behind schedule. While Paul was at the gas room we ran into another problem, when Joe analysed his mix it was incorrect, if i remember correctly he had a mix of 14/26. No good for what we wanted to do as it was hypoxic and even with this course hypoxic mixes aren't touched until then advanced mixed gas course. So now we had two sets of twins in the gas room waiting to be filled.
Since my gear was ready, as was dennis' rebreather we decided to assemble our kit and take it down to the pontoons so that less faffing about would take place when the mixes were correct, we went down loaded our equipment on the trolleys provided and went to the end of the pontoon, unfortunatly doing all this meant that i was sweating loads in my drysuit, something i would later regret.
At about 11.30am the mixes were finally correct, Joe was wearing holes into the bottom of his drysuit from all the marching he had been doing trying to keep calm about getting the wrong mix! But all was ok in the end. Joe and Paul met myself and Dennis on the pontoons at the waters edge were we had a thorough brief, as I was leading this dive I stated what my intentions were also.
Again like with the other dive a goal of ours was to recover dennis' DSMB and reel, however on this dive the odds were turned in our favour, we had a litter picker upper with us to reach down into this hole! We kitted up and then as I connected my inflator hose to hear gas, I look down to see that the male fitting had become lose and was not making a proper seal, bugger. An adjustable spanner was found and the noise disappeared so I clambered back into my mountains of gear for the final time. After buddy checks we all jumped in and descended to 6m for a final bubble check. After this we dropped stright down to 46m (see picture below). This time with the help of the garbage picker upper we got dennis' DSMB and reel, goal! I led the team down further to a planned maximum depth of 57m. Our plan was for 13 minutes at this depth with then an ascent to the top of the wall for a further 12 minutes. We arrived on the shot to ascend to the 30m shelf at 12:58, can't get much better than that I thought!
As we ascended I checked my instuments to see a problem, my gauge read 57.1m crap! I wondered what to do, to go onto the deeper and longer plan adds another 18 minutes of decompression to the run time. I decided against it, I couldn't of been at that depth for more than 5 secs and we were along way off doing a square profile at 57m (as you can see by the profile), with this in mind I decided to stick to the orginal plan and add a few minutes more decompression into the shallower stops.
Now we were swimming along the wall which turned out to be shallower than we thought about 26m we turned around at the right point and went back to the shot, damn 2 minutes to soon, not a problem but too soon back in my opinion. When we reached the shot dennis looked at my computer and seen the 57.1m, I got a tapping of the screen and he was less than impressed, fair enough I thought it should of never happened. Then he showed me Pauls computer 57.7m, damn now that was too deep so we had to go onto the deeper and longer plan. We waited at the this depth for about 5 mintues waiting for the run times to get back in sync, I started to get very very cold.
Lots of people say that trimix is a cold gas, I thought yeah right I dive in 5oC waters in winter it can't be any colder than that surely? Answer yes it bloody well can! Becuase i'd been sweating before the dive my drysuit was becoming an ice box, dennis seen me shaking and made me start to move around more, I warmed up abit but was looking forward to getting to the shallower stops! We started our main ascent plan after 34 mintues. While at this depth I did another check on my contents gauge.. 60 bar left! I couldn't believe it, were had this gas gone? I assumed something must have been turned off, so I started checking my manifold and pillar valves but nothing was wrong. It wasn't a problem I had 4 minutes of stops before I got to my switch depth and would be off my back gas. I also had two stages with the same mix in so plenty of gas would be available to me.
By the time we got to 15m we went through a nice thermocline, finally abit of heat i thought, we did the switch and carried on with the ascent till we got to 6m. I got to 6m checked my run time and seen that I had 18 minutes of stops at 6 plus Dennis wanted us to do some drills at the end of it. I wasn't that bothered it was nice and warm now, and my 60% stage now had me feeling great, however I wasn't going to tell Paul this and kept up some banter at 6m pretending at how unhappy I was!
We finished the deco and started the drills, nothing hard just shutdowns etc, after approximatly 75 minutes Dennis gave us the up signal, before we ascended we all cheered and high fived each other over the great dive we had just completed, dennis swam round and shook all our hands and then myself and Joe then assaulted Paul for the extra 18 mintues run time! We surfaced after 77 minutes and I was grinning from ear to ear, this type of diving was one of the main reasons why I took up the sport, it took me 3 years with BSAC to get this far, and about 130 dives but I was made up to have done it. We took our kit up to the cars and had a through debrief, myself and Paul got a good telling off for busting our depth but it showed the need to plan for when this happens! I asked dennis about my low gas and he reminded me that the deeper and longer plan will go into my reserve, also I had been leading the dive and also very cold so my SAC would have been higher than usual.
I can't recomened the SMG course highly enough, it was the first course I've been on were I found myself being challenged by the diving I was doing, and it was brilliant. I called this dive the BIG one for two reasons. Firstly it was by far the deepest I've ever been and also 60m is the same size as the first drop on the Pepsi Max big one in blackpool. That put things into perspective for me and made me realise even more that there is a lot of water in between me and the surface when I'm doing this type of diving. This course isn't for the faint hearted, it is challenging and also quite complicted, I like the physiology side of things because I want to understand more about DCS etc, this knowledge really helped me on the course so I would recommened anyone thinking of doing the course looked up some diving physiology and understanding the reason for the ascent profiles you will be doing. I must say a final thank you to Joe and Paul for coming with me and to Dennis for being our instructor and showing great patience with the kit problems we suffered with!
http://phildonegan.co.uk/images/deep_thumb.JPG (http://phildonegan.co.uk/images/deep.JPG)
Click image for a larger version.
Phil
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