Past NDL. And then this???

[KeithG]

What is the default setting on Subsurface for its Buhlmann algorithm? Does it use Gradient Factors, maybe 100/100 as a default? Perhaps that is why Subsurface gave the OP no significant deco but his Leonardo did. (I am assuming the OP is using the default Subsurface....)

I believe the default Subsurface algorithm is VPM-B with a conservatism level of +3. The default Buhlmann GF's are 30/70. My Uwatec Aladins seem to match Buhlmann 30/90.

The OP should be able to tell us how they have Subsurface configured.

 

[KeithG]

Isn't this kind of like telling someone to get a different doctor if they don't like the advice provided by the current doctor?

If someone doesn't like the advice provided by their current computer, they don't actually need to buy another computer. They can simply ignore the current computer... right? Essentially the same philosophy, but saves a good deal of money.

Stepfen, if I can offer one bit of advice that I didn't see addressed in any of the responses yet. Get in the habit of planning your dives, every dive. In this case, if you had spent 60 seconds with your buddy before that dive and compared the projected NDLs given by your computers for the next dive, you would have likely seen in advance a noticeable difference. You could then have discussed with your buddy how the two of you would handle the dive, and both of you would have been aware of the situation (i.e. that your NDL was going to be much less than his) before getting in the water.

When doing repetitive dives, I would go 1 step further and suggest that you have a high level plan for your complete day, not just the next dive.

 

[Beau640]

Ok. Now I see. English is not my native language. Hence I interpreted no 3) as time to spend on the next deco stop and not time to reach the next deco!!!

I thought the computer was telling me: Look, you will have to spend 4 mins deco at 3 meters while it was telling me, within 4 minutes you have to be at 3 meters ! It makes a lot much more sense to me now.

Thanks a million to help me see that

Think this was missed didn't see this addressed in the replies. You had it right the first time. The computer was telling you how long you have to spend at your deco stop.

 

[uncfnp]

I am not going to get into the ongoing algorithm debate. To @stepfen : this is a frequently discussed topic on SB that you jumped into with both feet. It is an interesting discussion and there is a lot of good info for a newish diver. But all the info can also be very confusing and sometimes seem contradictory (hence to SB debate).

If you can try switching Subsurface to VPM + 5 and see if the two "dives" are a closer match. If you do this let me know the result.

 

[Dan]

The OP's profile said his training is both PADI and IANTD. I assume the PADI certification is OW. With the PADI OW course, you have the choice of taking the table version of the course or the computer version. Can you tell me. @stepfen, which version it was?

In the table version of the course, you do not learn much about computers; you learn how to use the tables, and you learn to use procedures in case you unintentionally go into deco, procedures that would have been completely inappropriate to this incident and that were not mentioned. In the computer version of the course, you learn to use the ascent rate prescribed by the computer, and you learn to follow the directives of the computer in case of an unintentional deco obligation.

That's my case. I took the table version of the course and freaked out when I went into deco with my SUUNTO D4. I had a crash course on the spot on how to meet my deco obligation by following what was displayed on the screen, ascending to the ceiling at the rate shown on display (keeping the ascend rate bar graph from hitting the max and not hanging around in the deep or too slow of ascend rate either). Looking back, I wish I took the computer version of the course.

 

[boulderjohn]

Perhaps I missed this in the thread, but have you checked all your settings? I have two examples from my own past that might be of interest here. I used to own a Suunto Cobra, which ran roughly the same algorithm as your computer. I just checked the online manual for your computer, and I see it has the same features that I dealt with in the two experiences I will relate.

1. When I dived at Truk lagoon, my dive buddy (using an Oceanic computer), called me "captain Deco" because I was always getting to NDL long before he was. It was frustrating for both of us. Near the end of the week, I finally noticed that the settings for personal factors (fitness, etc.) were no longer at the 0 level where I had put them originally. They were up to the 1 level, the middle of the 3 possible conservatism settings.) It made a HUGE difference in my NDLs.

2. I stopped using that computer for quite a while after going to a different one, and for some reason I don't recall I mounted it to use while diving in Florida. I was intending to follow my new computer, but the Cobra was air integrated, and I planned to use it solely as a pressure gauge.

While on my second dive of the day, I thought about that computer, and tried to remember when I had used it last. I realized I had last used in diving in the Denver, Colorado area. I then realized that it must still be set to that altitude. I looked at it and saw that it was indeed set to the higher altitude setting, and it had me far into deco. The primary computer I was using on my wrist did not have me anywhere near deco.

As I said, your computer has both those settings, and if you are not on the most liberal, you will be heavily penalized.

 

[Asteve]

I think that the mistakes the diver made have been covered. A bigger problem is the fact the scuba industry can not agree on what algorithm I should use. When we were using dive tables pre-dive planning was easy, we could agree which table we would use and we would all have the same bottom time. We can not set cheap DC to the same algorithm. We can not use only one DC in a team.
I had this same problem when diving this DC. after the first 2 days I choose to stay above the group at all time and I would follow the NDL time up to the surface. I would surface 10 minutes or more before the dive leader ( yes I had to came up by my self, the group was not willing to dive my DC.) and he would have 10 more minutes left when he came up. We were doing the same dives all week and I never went deeper then him.
This DC is teaching new diver ( that may not under stand NDL well) not to follow their equipment because they see other getting more bottom time and having more fun. I am not saying not to follow your DC. I am saying that a new diver gets a mind set with this DC that it is so conservative, that they do not mine pushing the NDL line or blowing off a Dec stop. It has taught them it OK. This is good until they make a trip to the chamber or worst.
I replace my DC.

 

[AZNetEng]

@boulderjohn posted what I was going to. My wife inadvertently set her computer (Suunto Zoop) to A2 and her dive at the Blue Hole had her in deco. While this was a first for her she met the obligation and then back on the boat we figured it out.

OP, I think the answer that you seek is that you computer is conservative as compared to the rest of the group, and the planner you are using. Complicating it further is how the computer handles being "ignored" and the time it adds if the obligation is allowed to linger.

Your take aways from the discussion IMO should be to decide if you are going to continue to dive pushing your NDL's. If so then definitely get trained in DECO diving so that you can think and act when it happens again. More importantly it will allow you to plan for a better dive profile and ensure you have gas available for your obligation.

IMO every diver should understand what they should do and how to read their computer if they get notified of a DECO obligation. That however is a different discussion for another day/thread.

 

[Blasto]

This is why in this age of loosely-planned PDC dives some minimal deco education and simulated deco training should be part of any course that certifies one to depths where deco obligation is reasonably possible on a single al80.

Most rec divers will at some point touch their NDL, and at that point, realizing that they should do deco, but have no idea what it comprises and how to go about it, can put them in more trouble than continuing a violated table plan would.

 

[boulderjohn]

A bigger problem is the fact the scuba industry can not agree on what algorithm I should use. When we were using dive tables pre-dive planning was easy, we could agree which table we would use and we would all have the same bottom time.

Provided you all agreed to use the same tables. The differences between some tables is huge.

This DC is teaching new diver ( that may not under stand NDL well) not to follow their equipment because they see other getting more bottom time and having more fun.

There is indeed a big difference in some computer algorithms. Read enough threads about this on ScubaBoard and you will clearly see why the scuba industry does not agree on an algorithm to be used by all. If someone decides that one algorithm is better than another for whatever reason, then that person should make an educated decision on which one to use. I myself have read a lot of information on various algorithms, and I have certainly made my mind up as to which one(s) I prefer.