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Scuba Forum / UK Scuba / June 2009Suunto Vitek Ascent rates
I did a dive at the weekend on the Frognor, which is about 35m. After 29 minutes, and with 10 minutes required to reach the surface, my buddy and I set off from 34m. It took us 5 mins to reach 6m, which works out at an ascent rate of less than 6M/min. Looking at the profile on my PC the ascent is as close to a continuous line as you could hope to see, yet I ended up with 3 SLOWs indicating I was ascending too fast during that phase of the dive. What sort of ascent rate does the Vitek use? BSAC recommend 15M/min max and we were well below that, possibly too far below that if we'd had a serious deco obligation. The computer is not on the arm that I use to vent air from suit or BC and I have no recollction of having had to move my arm to any extent, my buddy was working the DSMB I was just floating. I've had SLOWs in the past in situations where something happened and they were deserved but in this case the ascent was completely uneventfull. Why would I get slow warnings from the computer in this situation? Just curious. Ron. > I did a dive at the weekend on the Frognor, which is about 35m. After > 29 minutes, and with 10 minutes required to reach the surface, my [quoted text clipped - 21 lines] > > Ron. Have you got it in RGBM mode? (Reduced Gradient Bubble Mode) see http://www.dive-tech.co.uk/resources/suunto-rgbm.pdf or deep stop mode? Dont claim to understand it, but it makes you do deeper safety stops and more of them, rather than one final stop. One example is that for a dive to 34 is that you should stop at 17m, then at 8, then at 5. Thus is that mode you would have broken the first stop and the second. Also, assuming it recalculated after the first miss, you probably missed another stop somewhere. Actually, by all ways of looking at it - you should be bubbled up or dead! By the PADI rdp on air you had about 10 mins bottom time without deco. Doing a simulation on a Suunto D9 on air Can't! So you must have use 35% Nitrox? Using 34% Nitrox (max depth 36) you needed 10 mins to surface but by the time you reached 6m, you still needed 7m safety stop at 5m. And RGBM mode is SELECTABLE for air, seems to be compulsory for Nitrox in that you can't seem to turn it off. Hello Blah, No this is an old Vitek and it doesn't have deep stop mode. When I left the bottom it told me my cielling was 3M, nothing before that. I was on 30% nitrox, the max for that depth. Ron. >> I did a dive at the weekend on the Frognor, which is about 35m. >> After 29 minutes, and with 10 minutes required to reach the surface, [quoted text clipped - 45 lines] > And RGBM mode is SELECTABLE for air, seems to be compulsory for Nitrox > in that you can't seem to turn it off. > Hello Blah, > No this is an old Vitek and it doesn't have deep stop mode. > When I left the bottom it told me my cielling was 3M, nothing before that. > I was on 30% nitrox, the max for that depth. > Ron. Therein lies your problem - my Suunto simulation for 30% shows a max depth of 38.6m , and a total dive time with deco of 51 minutes on a Vytec, so you missed some(lots) deco (assuming you did 29,5,3). you should have done 29,5,16 according to the simulator. Interestingly if you'd come straight up 34m>6m in a minute, the simulation says - 29.1,7 - ie a total dive time of 37 as opposed to 50!. The slow ascent is walloping you by adding nitrogen. Hmm. Have you got Suunto Dive Manager? is your email addy right? >>> I did a dive at the weekend on the Frognor, which is about 35m. >>> After 29 minutes, and with 10 minutes required to reach the surface, [quoted text clipped - 45 lines] >> And RGBM mode is SELECTABLE for air, seems to be compulsory for Nitrox >> in that you can't seem to turn it off. Hello Blah, >> Hello Blah, >> No this is an old Vitek and it doesn't have deep stop mode. [quoted text clipped - 15 lines] > > Have you got Suunto Dive Manager? is your email addy right? According to my BSAC tables a 30% notrox mix has a max depth of 36m with a PPO2 of 1.4. I guess you're using a higher PP02 in your calculation? The dive was to 35m and the max I got was about 35.3m. After 29mins it wanted me to take 10mins to the surface and it didn't want any stops below the 3m ceiling. I'm using Suunto Dive manager to display the dive profile and the ascent looks almost perfect on the graph, other than being too gentle/slow, and showing 3 SLOW events. The email address I'm using is one I use as a black hole, every so often I go there and just delete all the emails. I use it in many forums/websites and now it gets hundreds of spam emails per day . Ron > Hello Blah, > [quoted text clipped - 35 lines] > > Ron. Has your version of DM got the simulator built in? If not I could point you to a copy. First time I've used the simulator tho, and maybe I'm using it wrong, but it doesn't seem to simulate warnings - you can set a profile of 100m on air for 30 mins and then up to 3m and you don't get any warnings about PO or ceilings or ascent rate - which seems a bit lame. And only when putting a VERY deep dive in - to say 70m does the ceiling start to increase from 6 to say 14. Perhaps it just need more playing! And yes I used Po of 1.6 > I did a dive at the weekend on the Frognor, which is about 35m. After > 29 minutes, and with 10 minutes required to reach the surface, my [quoted text clipped - 21 lines] > > Ron. Here you go: http://www.suunto.com/suunto/main/article_2column.jsp?CONTENT%3C%3Ecnt_id=101341 98673958595&FOLDER%3C%3Efolder_id=1408474395903548 > What sort of ascent rate does the Vitek use? Slow, very slow. Several of us have been shouting warnings about the ultra conservative Suunto computers for years. Check out your partial pressure and depth limits and you'll find that your computer doesn't do them right either. >> What sort of ascent rate does the Vitek use? > >Slow, very slow. Several of us have been shouting warnings about the ultra >conservative Suunto computers for years. Check out your partial pressure >and depth limits and you'll find that your computer doesn't do them right >either. After I'd sold on my Vyper for a Quantum I did a dive with a friend still using his Vyper. We were at 40 - 42 metres for sometime, probably on 28%. The oxygen warning on his Vyper was off the scale before we left the bottom.  SignatureIan "Bother!" said Pooh as he drank Roo's blood Hello Ian, >>> What sort of ascent rate does the Vitek use? >>> [quoted text clipped - 7 lines] > probably on 28%. The oxygen warning on his Vyper was off the scale > before we left the bottom. I'm fat and over 50 so the Vitek being overly conservative doesn't bother me. It still lets me do the diving I want to do. I also changed to a 50% deco mix from 20m but didn't tell my computer so I'm VERY conservative myself anyway. If I hadn't already been very conservative I might have chucked in a deep stop too while doing the gas change. I wasn't pushing any limits here, other than boredom on the ascent. On a deeper/longer dive I might get closer to the Vitek's limits and told it about the deco gas in the understanding it is also conservative. I'm just trying to work out why I got SLOWs. The slows were not at the time of the gas change, they were spread out. Ron >I'm just trying to work out why I got SLOWs. >The slows were not at the time of the gas change, they were spread out. Momentary high ascent rate. OK different computer but last night I popped into Wraysbury with my daughter to check out some kit. I noticed an ascent warning going from 4 - 3 metres, since I could see both platform and a line I knew I had barely moved but a slight ascent coupled with bringing my right arm up was enough. SignatureIan A man with his hands in pockets feels foolish The computor monitors depth and time continuously during the dive, so when you had 3 momentary periods of fast ascent (i.e. faster than 10 m/min) it gave you 3 warnings at the time; however it only records samples of data into its memory every 20 seconds (or whatever you have set the sampling rate to be,) so unless it happened to be recording during those fast ascents they will not show later on. Cliff. >I did a dive at the weekend on the Frognor, which is about 35m. After > 29 minutes, and with 10 minutes required to reach the surface, my [quoted text clipped - 21 lines] > > Ron. Hello Cliff, The 3 slows do show up on the Dive Manager software but when I run the dive profile on the Vitek I only see 1 slow. How "momentary" are these periods. I've got the Vitek set to collect the largest number of samples as I download them fairly regularly to my PC so I'm not concerned about keeping old dives on the Vitek. Could the shorter recording period make the Vitek actually take samples more often? Are you saying that if I raised my arm quickly, for example to adjust my mask, and the sample was taken just as I did this I'd get a slow? I.e what is recorded is an instantanious snapshot rather than an average over the sample interval? Ron. > The computor monitors depth and time continuously during the dive, so > when you had 3 momentary periods of fast ascent (i.e. faster than 10 [quoted text clipped - 4 lines] > > Cliff Hello all, I've done some more calculations using the profile information used to draw the graph. While the overall ascent from 34m to 6m was at a rate of 6M/min the detail wasn't quite as smooth as the graph led me to believe. I suspect the graph drawing software is using some sort of smoothing rather than just join the dots? At 16M I rose 2.2M in 10 seconds, which works out at 13.2M/min. At 14M I rose 1.8M in 10 seconds, which works out at 10.8M/min. At 7M I rose 1.5M in 10 seconds, which works out at 9.0M/min. Everything else on the ascent was roughly 1m per interval or 6M/sec between 34M and 6M. These were the 3 events that showed up as SLOWs in the profile data and graph but only the first one showed up as a SLOW on the Vitek and in the picture of the vitek in the top right of the graph when you move through the dive in Dive Manager. All of these are below BSAC's ascent rate guideline of 15M/min. I suspect the Vitek's ascent rate is not linear all the way to the surface so the last one might be justified as I'm getting close to the surface but BSACs recommeded ascent rate from 6m to the surface is still 6M/min. I guess what I've learned is 1) The graph won't show up short relatively fast ascents, other than by the SLOW symbols, the graph can still look smooth. 2) Not all SLOW events are reported on the Vitek screen. 3) I didn't realise just how conservative the Vitek ascent rate is. 4) My ascent wasn't as text book as I thought it was. Thanks for your time guys, Ron > Are you saying that if I raised my arm quickly, for example to adjust my > mask, and the sample was taken just as I did this I'd get a slow? Exactly. Cliff. |
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