Does anyone who understands the Suunto algorithm know if this is a valid statement?

[gasgirl]

"Realistically on a Suunto with 5 minutes showing (2 mins mandatory + 3 mins safety stop) you're not in much danger at all. You can probably even go across that by another 5 mins at depth and while the Suunto will probably be telling you 10+ mins of deco to do, you'd be fine blowing it off if the absolute worst case happened to you."

I started a thread in the Advanced Scuba Discussion asking about how best to dive in Cozumel while using a Suunto but I was getting off topic from getting this question answered.

 

[TSandM]

If you look at what different dive computers will come up with for no-deco time at various combinations of depth and time, the "RGBM" algorithm that Suunto uses often comes up on the conservative end. That means that, if you dive with a friend who has an Aeris computer, your computer may show you into deco, when your friend's computer, which has done the same dive, still indicates remaining no-deco time.

Does this mean that you are "safe" ignoring the mandates of your Suunto computer? Maybe . . . but the minute you do that, you are outside the bounds of the computer algorithm you have chosen to use, and you are in unknown territory. I can guarantee you that Suunto didn't do any tests to find out if you could blow off what the computer thinks are 10 minutes of mandatory deco . . . But Aeris probably did some testing to make sure that people could dive THEIR algorithm safely.

When you get toward the edges of the models, there are enough differences, based on the differing assumptions and constants that are chosen by the developer, to cause some problems when diving mixed teams on computers. The general advice is to follow the most conservative device, but the real answer is that decompression is not an exact science, and there are personal and situational variables that aren't taken into account by computers, that can affect your safety.

It's very bad advice to tell someone it's fine to blow off mandatory deco . . . but with any computer or model, if I had ten minutes or less of mandatory deco and I had a situation where my safety depended on getting out of the water (I think I'm having a heart attack, or I've got a bleeding wound that won't wait ten minutes) I would omit the deco. But I think, absent a situation like a medical one, most cases where you might want to omit the deco (being low on gas, or over the time limit for the dive, or cold) are situations that should have been remedied by not incurring the deco in the first place.

 

[Kilili]

I don't understand it in depth, but you might find this article of some interest. http://ns.suunto.com/pdf/Suunto_RGBM.pdf
There's also an interesting point about long-term damage without short-term symptoms.

 

[gasgirl]

.It's very bad advice to tell someone it's fine to blow off mandatory deco . . . but with any computer or model, if I had ten minutes or less of mandatory deco and I had a situation where my safety depended on getting out of the water (I think I'm having a heart attack, or I've got a bleeding wound that won't wait ten minutes) I would omit the deco. But I think, absent a situation like a medical one, most cases where you might want to omit the deco (being low on gas, or over the time limit for the dive, or cold) are situations that should have been remedied by not incurring the deco in the first place.

I totally agree with all your points in you post - I don't think blowing off mandatory deco is ever a good idea.

I think the problem is I am not doing a very good job at posing the question I am asking.

This is what I asked in the other thread that I posed in the Advanced Scuba Discussions:

"My questions for those familiar with Suunto computers are :
1. Would you allow the Suunto computer to go into deco and assume it will clear as you slowly ascend (10 ft/min) with mulitlevel stops for several minutes at 50 and 40 and 30 feet?
2. If yes, what is the maximum deco obligation that you would incur (assuming, of course, that this still falls within the gas plan)?"

I have been given the impression that it is OK to allow up to 10 minutes of ASC time on Suunto and it will actually clear before you get to your safety stop as it will continue to give you credit for a continuous decompression model as you ascend.

So far, the only reply on that thread so far that really seems to address answering whether that assunmption is valid or not is that it will depend on the actual dive profile - which is true enough!

 

[emoreira]

Suunto RGBM algorithm is known to be conservative. I don't know if your PDC allows to be configured less conservative.
If you are not willing to follow the indications of your dive computer, you should :
1) Set it as gauge and use it as depth timer and dive tables.
2) Sell it and buy a new one with a less conservative algorithm like Oceanic.
Remember that a PDC is like a "Big Brother" that tells you what to do. If you opt to randomly skip the deco requirements, it will get upset and will penalize you the next dive.

 

[gasgirl]

I don't understand it in depth, but you might find this article of some interest. http://ns.suunto.com/pdf/Suunto_RGBM.pdf
There's also an interesting point about long-term damage without short-term symptoms.

The points in the section on Practical Implications of the Suunto RGBM algorithm on page 4 and the section on Controlling Bubble Formation While Maximizing Off-Gassing on page 8 is exactly what I am trying to determine is safe or not with this question that I posed in my other thread:

"Would you allow the Suunto computer to go into deco and assume it will clear as you slowly ascend (10 ft/min) with mulitlevel stops for several minutes at 50 and 40 and 30 feet?"

Thanks for the link!

 

[cbm32]

I dive a Suunto Gekko. I do not pretend to know understand the algorithm. I have however run into deco a couple of times and it was a simple matter stay at the depth for the time required. I have also seen that I was getting close to deco and come up a few feet and watched the Gekko make a time left until deco adjustment. If I had plenty of gas I wouldnt worry about it a whole lot personally.

I would not personally intentionally go into deco but, from my limited experience, a few minutes of deco would clear up with no problem on a multi level dive like you are describing. The key for me would be having plenty of gas.

 

[bbarnett51]

.It's very bad advice to tell someone it's fine to blow off mandatory deco . . . but with any computer or model, if I had ten minutes or less of mandatory deco and I had a situation where my safety depended on getting out of the water (I think I'm having a heart attack, or I've got a bleeding wound that won't wait ten minutes) I would omit the deco. But I think, absent a situation like a medical one, most cases where you might want to omit the deco (being low on gas, or over the time limit for the dive, or cold) are situations that should have been remedied by not incurring the deco in the first place.

I totally agree with all your points in you post - I don't think blowing off mandatory deco is ever a good idea.

I think the problem is I am not doing a very good job at posing the question I am asking.

This is what I asked in the other thread that I posed in the Advanced Scuba Discussions:

"My questions for those familiar with Suunto computers are :
1. Would you allow the Suunto computer to go into deco and assume it will clear as you slowly ascend (10 ft/min) with mulitlevel stops for several minutes at 50 and 40 and 30 feet?
2. If yes, what is the maximum deco obligation that you would incur (assuming, of course, that this still falls within the gas plan)?"

I have been given the impression that it is OK to allow up to 10 minutes of ASC time on Suunto and it will actually clear before you get to your safety stop as it will continue to give you credit for a continuous decompression model as you ascend.

So far, the only reply on that thread so far that really seems to address answering whether that assunmption is valid or not is that it will depend on the actual dive profile - which is true enough!

I will try to answer in a better way. If you are at 80' for 40mins you will be in deco. If you are at 125' for 15min you will also be in deco (assuming you are diving air). Those are two very different profiles and the computer is likely to react differently on ascent. So it is impossible to plan on it.

I recently had a 5 min obligation on my second dive. First dive was max depth of 105' for around 38min. I was not at max depth for the entire dive. I had an hour SI and then had my second dive at Max depth of 92' for I can't remember how long. I had a 5min obligation. I ascended slowly, took my time watching some barracuda, and still had my deco obligation. No big deal I extended my safety stop and enjoyed watching a shark below. But my point is I barely exceeded my bottom time and my deco did not clear.

I'm other words the advice that you got is not altogether true.

 

[gasgirl]

I dive a Suunto Gekko. I do not pretend to know understand the algorithm. I have however run into deco a couple of times and it was a simple matter stay at the depth for the time required. I have also seen that I was getting close to deco and come up a few feet and watched the Gekko make a time left until deco adjustment. If I had plenty of gas I wouldnt worry about it a whole lot personally.

I would not personally intentionally go into deco but, from my limited experience, a few minutes of deco would clear up with no problem on a multi level dive like you are describing. The key for me would be having plenty of gas.

Thanks for sharing your experience with the Gekko - it seems consistent with what I have been told and I am just posing the question to formulate my plan in case this scenario comes up when I am drift diving in Coumel in a couple of weeks.

ie. Is it better to continue the dive with the rest of the group and incur the ASC time obligation or is it better to end the dive and go to the surface knowing that I have now separated from the group (presumably with my buddy) and risk drifting to Cuba???

 

[Kilili]

1. Would you allow the Suunto computer to go into deco and assume it will clear as you slowly ascend (10 ft/min) with mulitlevel stops for several minutes at 50 and 40 and 30 feet?

To the point, I would never make such an assumption.

If the computer goes into deco, one must allow for working off the extra time. If it occurs by doing multilevel stops, so be it. However, without the complete dive profile, who can definitively say in advance?

You've asked for help, and many have attempted to do so. I get the feeling that you're looking for someone to sanction what you already intend to do. That's fine. In the end, it's your decision, and you accept whatever consequences that follow from it. As for what you decide, it really makes no difference to me. I have no doctrine to promote. I just offer information.