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Looking at the profiles, you could have violated the NDL in the second dive of day two (second plot, or was that the thrd dive?). The NDL for 27 m given by the Suunto D4 Dive Planner with no accumulated nitrogen is 31 minutes with a setting of 100% RBGM (as shown on the Dive Manager plot above) and EAN 32 %.
The D4 has three dive modes - freediving, air and nitrox. It doesn't have a gauge mode. As mentioned above, if you scuba dive in freedive mode it locks you out for 48 hours after ten minutes. The display in freediving mode shows only depth and dive time which is similar to the D6 gauge mode.
If you violate the NDL's in air and nitrox mode then you get an error message and the display changes. The following are extracts from the D4 manual:
Once in the permanent Error mode, only the Er warning is shown in the center window. The dive computer will not show times for ascent or stops. However, all the other displays will function as before to provide information for ascent. You should immediately ascend to a depth of 3 to 6 m/10 to 20 ft and remain at this depth until air supply limitations require you to surface.
After surfacing, you should not dive for a minimum of 48 hours. During the permanent Error mode, the Er text will be displayed in the center window and the planning mode will be disabled. (pg 34)
In addition, an Error warning (Er) reminds you that you have only three minutes to correct the situation. You must immediately descend to, or below, the ceiling. If you continue to violate the decompression, the dive computer will go into a permanent Error Mode. In this mode, the instrument can only be used as a depth gauge and timer. You must not dive again for at least 48 hours. (pg 58)
The manual is available on line.
The graphs indicate you were operating in the 100 % RGBM mode.
Last edited by Foxfish; February 13th, 2012 at 07:46 AM.
The Suunto D4 also allows experienced divers who are willing to accept a greater level of risk to adjust the RGBM model. The default setting is 100%, which gives full RGBM effect. Suunto strongly advises you to use full RGBM effect. Statistically, very experienced divers have less incidents with DCI. The reason for this is unknown, but it is possible that some level of physiological and/or psychological accommodation can take place when you are very experienced as a diver. Thus, for certain divers and diving conditions, it may be desirable to set attenuated (50%) RGBM mode. See Table 5.7, RGBM model settings. (pg 45)
LDS only have Oceanics and Liquision...and Suunto support has closed the case, saying we dived in Free mode.
We did not plan the dive,the Diveleader told us to stay close to the DM, or else we could get problems following him in strong currents.
Also, when the D4's failed, we had problems telling the DM because he swam fast and was a bit ahead of us.
This was my buddys first dive this day(my no.2), so Deco should not be an issue, at least not for my buddy!
After wreck diving on Malta, I pay very close attention to NDL, because I got + 3 minutes on a dive.......
If the computers went in Deco mode, the display will show additional Deco time in the display. I have had 3minutes deco in addition to the safety stop once before.
This time, the display only showed minutes and seconds, counting. If I went up, it counted one way, down, the opposite.(it's been a month now, so I don't remember too well). And, as mentioned earlier, for one diver(my buddy), it was the very first dive this day.
After all these replies, it looks like we both must have been diving in Free mode...even if I was 100% convinced from the start that it was in Nitrox mode......
Yearly battery change was in May 2011, but since my D4 randomely was resetting Time/date to 2007, the distributors technician checked it, pressure checked it(displayed depth 40cm less), and changed battery again 30/12-2011, this issue disappeared....
Main reason for changing batteries every year, is because both D4's stopped working on the same dive once....
It seems like buying a backup computer will be a good idea!
Interested to read your comment about the dive manager. I did a dive recently where we had an almost identical problem. The dive manager expected us to follow his computer. On the second dive this would have got very close to exceeding NDL on my computer. He expected us to follow at his pace which was too fast for the general group in a relatively strong current. He ended up losing two divers after traveling from one end of the wreck to the other and then had to swim around trying to find them. Seems like a recipe for disaster.
After all these replies, it looks like we both must have been diving in Free mode...even if I was 100% convinced from the start that it was in Nitrox mode......
It seems like buying a backup computer will be a good idea!
Based on what you've written, it seems like the most reasonable approach would be to simply ensure that your computer is set properly (Dive Mode: Air or Nitrox).
Even if you had been using a backup computer on the repetitive dive series in question, there's a good chance that it would have been set the same way as your other computers...and would have gotten locked out as well.
My experience with wearing a Suunto Vyper and Uwatec Galileo Sol at the same time is that the Suunto (at P0) is more liberal on the first dive, but on repetitive diving it flips--the Suunto becoming increasingly conservative. It's somewhat like the Uwatec with a higher conservatism set (MB>0) and the optional Level Stops of the Uwatec are true deco stops on the Suunto. The old Vyper does not allow the 50%RGBM so I can't comment on it.
RGBM 100 and RGBM 50 did not differ too much in this review: A sense of algorithm - Divernet
which I think worth reading for every recreational diver looking for a dive computer :-)
My experience with dive buddies using Suunto has been poor. Maybe Suunto is difficult to use? There batteries are/where not user replaceable so that has been an issue. I think that has changed. They seem to lock out users for very minor violations for 48 hours.
I was diving a similar profile vs a buddy that got locked out, so the dive profiles were safe by other computers standards. User error may have been involved, but Suunto seems prone to locking up if users don't do things by their book. Another common mistake is to forget to set you Nitrox profile. So you are diving 32% but the computer is set to 21%. That does not lock out the Aeris, just adjust the mix for the next dive. The computer will penalize you thinking you were diving 21% so that second dive should be shallow if possible. You could also set the puter to a higher mix, but games like that can be dangerous.
My Aeris Epic is not conservative, and will not generally lock users out. Maybe Suunto's ultra conservative profile is a good thing. My experience is divers ignore it and dive anyway as its often a setup error vs a real violation.
I recommend Oceanic or Aeris. Simple to use, not much you can do to mess them up. Just make sure you are in DIVE mode when you ascend. Check the mix if you are diving Nitrox. Realize that If you are diving like a bonehead you can get locked out of most computers.
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Originally Posted by DiveNav
