why is my d4 giving me a 10 minute deco stop??

[rab1412000]

hi guys

ive used my d4 on 26 dives and i love it. however during my 3 dives yesterday something strange happened.

on our first dive i incurred a one minute deco penalty when i shot up too fast while having difficulty deploying my smb on a current safety stop. total dive time was 49 min at max depth of 101fsw. we then proceeded on a brief surface interval of 1:11 hrs.

our next dive was 57 min with a max depth at 83fsw. the wierd thing is was given a deco penalty of 10 min (ceiling of 10 ft) plus the 3 min ss. the deco penalty only counted down when i was at safety stop level . now afaik the deco penalty will start countinh down as long as you slowly ascend towards the ceiling. mine however only started counting down when i reached the recommended ss level of <20ft.

my third dive was a no deco dive.

my question is, is this normal? could the fast ascent penalty be the one causing this?
my former deco dives would all count down as long as i slowly ascended and by the time at my ss the deco count down has usually elasped. im not a dive computer guru by any stretch of the imagination but i read the manual thoroughly and read a lot of SB posts re dive computers.
given suuntos somewhat dodgy reputation in its latest dive computers, i would really like to know...

thanks in advance

 

[imwright1985]

Could be a number of things, I would start with double checking the air/nitrox mix and see if that is right, then move into what the safety settings are and check that to see if it is set to a safe level for you. Other than that it could be from the kinda fast ascent

 

[rab1412000]

all nitrox and safety settings are set to default so it couldnt be that...

 

[DevonDiver]

The new range of Suunto computers can give you a 1 min stop if you exceed a safe ascent rate. This is certainly mentioned in the D9 manual.

It's hard to comment on the 10 min deco obligation, without knowing your exact profile. However, you have to follow an appropriate speed on ascent. Too fast and you super-saturate to excess. Too slow and you wont be credited for the effect of pressure differential releasing nitrogen from your system. Basically, the computer algorythm produces an optimal 'curve' for your ascent. Too much variance +/- from that curve will screw your predicted off-gassing.

I've done plenty of dives....where deco reduces on ascent, where it is unaffected by ascent until I reached stop depth and, also, where it has continued accumulating on ascent. This happens on all the computers I've used (Suunto Vyper, D9 and Apeks Quantum).

 

[battles2a5]

What was your average depth on those dives? Max depth doesn't tell us much, but given your stated max depths and run times you could have easily exceeded NDL's and incurred a legitimate deco obligation. I don't see a reason why your computer wouldn't start "counting down" until you hit your safety stop (again, can't really help without an idea of the profile) but after two long dives at shallower depths you are loading slow compartments so you aren't going to clear them on the ascent like you would deep stops. Suunto's are conservative to begin with, so that may be a factor as well if you do these types of profiles normally.

You mentioned doing deco dives previously. If you are doing this on a regular basis, might I suggest taking a deco procedures class so you have a better understanding of what is happening in your body instead of riding a computer?

 

[vladimir]

hi guys

ive used my d4 on 26 dives and i love it. however during my 3 dives yesterday something strange happened.

on our first dive i incurred a one minute deco penalty when i shot up too fast while having difficulty deploying my smb on a current safety stop. total dive time was 49 min at max depth of 101fsw. we then proceeded on a brief surface interval of 1:11 hrs.

our next dive was 57 min with a max depth at 83fsw. the wierd thing is was given a deco penalty of 10 min (ceiling of 10 ft) plus the 3 min ss. the deco penalty only counted down when i was at safety stop level . now afaik the deco penalty will start countinh down as long as you slowly ascend towards the ceiling. mine however only started counting down when i reached the recommended ss level of <20ft.

my third dive was a no deco dive.

my question is, is this normal? could the fast ascent penalty be the one causing this?
my former deco dives would all count down as long as i slowly ascended and by the time at my ss the deco count down has usually elasped. im not a dive computer guru by any stretch of the imagination but i read the manual thoroughly and read a lot of SB posts re dive computers.
given suuntos somewhat dodgy reputation in its latest dive computers, i would really like to know...

thanks in advance

Yes, it was probably a penalty for the fast ascent. Here, from the D9 manual:

DO NOT EXCEED THE MAXIMUM ASCENT RATE! Rapid
ascents increase the risk of injury. You should always make the
Mandatory and Recommended Safety Stops after you have
exceeded the maximum recommended ascent rate. If this
Mandatory Safety Stop is not completed, the decompression
model will penalize your next dive(s). Continuous ascent rate
violations will result in Mandatory Safety Stops.

 

[rab1412000]

Yes, it was probably a penalty for the fast ascent. Here, from the D9 manual:

thanks for the info but i did complte my deco penalty of 1min for the fast ascent.
i think it still penalized me for the fast ascent though during the 2nd dive.

 

[vladimir]

My D9 has penalized me in much the same way. If you get a 10 minute stop on what was a planned no-deco dive, chances are it's a penalty. If it were a 3-minute stop it would be more of a mystery.

 

[Jonny boy]

because you overstayed you NDL and the comp decided that you had a 10min obligation is the obvious answer. With regard to counting down the deco stop timing, the comp will only start counting down when you are within the 'ceiling' and the 'floor' of the optimum stop window, if you have not yet reached the floor then it will not o****down and if you exceed the ceiling you have 3 minutes to return to the appropiate depth before the comp locks out, at least that is my understanding of the suunto programming. The comp will count down slower the closer you are to the floor of the stop and will count down quicker when you are at the ceiling, in the manual they refer to this as continuous deco

 

[rab1412000]

My D9 has penalized me in much the same way. If you get a 10 minute stop on what was a planned no-deco dive, chances are it's a penalty. If it were a 3-minute stop it would be more of a mystery.

whats really mystifying me is the fact that when i started ascending from my max depth ( the floor) the deco time still kept adding deco minutes and only started the deco countdown when i was at my ss.
usually upon hitting deco, the computer will start the deco recomended safety stop when above the floor.
but looking at my log think i really did deserve that 10-minute deco