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

[LowVizWiz]

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???

#25

And Cuba is not such a bad place for tourist anyway! On the plus side, your deco would be cleared by the time you get there

 

[Kilili]

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???

I would never let the actions of the group override my common sense regarding safety. I've been diving in Cozumel many times. I jump in with a camera, and before I know it, everyone else is gone.
Do I care? No.
Have I been to Cuba? Not yet, but wouldn't it be a great story?
Has the boat crew ever forgotten me, or has it ever caused a problem? No.
Though being in the water alone, even for a short time may not suit anyone. I still think it wise to adhere to the first sentence.
In Cozumel, regardless how you do it, have a whistle or some such, plus a surface marker that can be seen in choppy water, not one of those dinky 3-4 ft things.

 

[TSandM]

Going into deco, and letting the computer clear as you multi-level the dive, is what's called a technical dive . . . No, seriously, it is! That's exactly what we do; we do dives that violate the no-deco limits, and we do the amount of deco that's required, sometimes accelerating it with other gas mixes.

There are a few things that change when you do that. One is that you HAVE to plan your gas, and this one of the big reasons why most recreational divers shouldn't even think about going into deco. If your computer shows ten minutes of deco, but you only have 300 psi left in your tank, what are you going to do? What if your buddy runs OUT of gas before you've completed your deco -- do you have enough to get you AND him through? Most people don't do the calculations to know how much gas they need at depth, and how much for deco, and how much for contingencies, but technical divers spend a LOT of time doing this.

Second, if you are going to incur a deco obligation, you have lost the ability to make a direct ascent to the surface with a reasonable likelihood of coming out unscathed. That means you now have to solve problems where you are. A lost mask, a malfunctioning regulator, bad cramps . . . doesn't matter; you have to stay where you are until you have done your time. Technical divers spend a lot of time practicing emergency procedures and drilling coping with failures -- and they set their gear up with a lot of redundancy, so if something fails, they have a backup. Most recreational divers don't do this -- one tank, one first stage, one buoyancy source.

Now, admittedly, the small amounts of deco you're talking about, and especially with a conservative algorithm, may not put you at such a high degree of risk. But you bought the computer because you wanted something to tell you how long you could safely spend underwater -- and now you're proposing to ignore it. Since the strategy I use for decompression does not involve a computer, I don't necessarily condemn this. But you have to be sure you a) have the knowledge to do it, and b) you're willing to accept the risks of doing something which is not tested, and is certainly beyond the representations the computer manufacturer made to you when you bought the thing.

I believe the CMAS 3* rating includes a little backgas deco -- deco is not black magic. But it requires understanding and acceptance of risk.

 

[gasgirl]

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.

Ok, sorry if I seem like I am being difficult. I really do appreciate all the help I get from everyone who takes the time to answer. I guess I thought there was a simple yes or no answer to my question I posed if someone knew the way the Suunto algorithm was doing their calculations. And yes, I always take full responsibility for the way I choose to dive.

---------- Post Merged at 03:03 PM ---------- Previous Post was at 02:57 PM ----------

#25

And Cuba is not such a bad place for tourist anyway! On the plus side, your deco would be cleared by the time you get there

LOL! I think I have exhausted the goodwill of SB members. My dive plan now includes bringing my passport in a ziploc.

 

[cbm32]

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???

I have also encountered a situation similar this but did neither of the things you are contemplating. I was very close to going into deco but had plenty of gas and the rest of my party was blissfully carrying on. I chose to mirror my party from ten or twelve feet above. My Gekko was happy and I was not, what I consider, separated from my group. shortly after I made my depth adjustment the DM saw me above everyone else an quickly came up to see if there was a problem. I got him to understand why I was where I was rather easily, we gave each other the OK sign, and he resumed leading the group. Later, back on the boat, the DM indicated I had acted just as he would have wished me to act. Not sure all DM's would feel that way and wont be surprised if I hear just that after posting this.....but it worked for us on that dive ...

 

[Paul S]

If you need more time before going into deco, don't try to "play" the computer, use nitrox.

There's a couple of things to be aware of, so make sure you've been taught how to use it, but it's much safer than trying to second guess a computer doing a calculation none of us fully understand.

 

[lamont]

"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.

I think that's basically a true statement but its misleading.

Your risk of getting bent, particularly getting bent severely is very low when you've got a few minutes showing on a sunnto. They are conservative, and there's a ton of padding baked into the recreational NDLs anyway.

However, if you're using that padding up without knowing how to decompression dive then you start running higher risks. If you are consistently diving at a level where your computer is requiring 5-10 minutes of deco and you're not ready to /absolutely/ do that deco in terms of gas management and skills, then you're going to be in a world of trouble if you go over time and you start looking at 20+ mins of deco because of getting delayed at depth due to current or gear problems, or simple inattention. And recreational divers are not operating in a system where they're ready to absolutely do the deco. They're operating in a system where 99 dives out of 100 they'll do the deco and get complacent, but if they have a free flow at depth, their buddy will be too far away, they won't be able to compete a basic gas share and they'll need to rely on a CESA. You can even push the NDLs out to a few mins of mandatory decompression and if you CESA you'll have a pretty good chance of just feeling a bit like crap and sleeping it off. But combine going overtime, racking up 20 mins of deco, and then needing direct access to the surface and a chamber ride at the very least starts to become much more probable.

So...

True, that the risk is very low even with a couple mins of deco.

False, that you can use that as a rationale to consistently push the NDLs dive-after-dive without decompression training.

And one useful takeway is that as long as you're not consistently planning on pushing over the NDLs, you don't need to panic if you accidentally go over the NDLs. Provided you have the gas you can exit your dive in an organized manner and clear your computer and its not a huge risk. Getting anxiety and a racing heartbeat and violating STOP, THINK, ACT principles just because one minute you were on one side of an entirely imaginary line and the next minute you weren't is not going to be a helpful reaction.

And one final thing is that playing the least-conservative computer game is probably not a good idea. Better to play the more conservative one. Although sometimes suuntos give silly answers for repetetive dives where I think it'd be fine to trust the PADI RDP as a tie-breaking authority (in other words, double-check what your computer says against tables before you start to disregard it).

---------- Post Merged at 03:25 PM ---------- Previous Post was at 03:19 PM ----------

If you need more time before going into deco, don't try to "play" the computer, use nitrox.

Completely agreed, however...

There's a couple of things to be aware of, so make sure you've been taught how to use it, but it's much safer than trying to second guess a computer doing a calculation none of us fully understand.

Speak for yourself.

I wrote my first ZHL-16b implementation in the time between doing my open water course and doing my first open water dive. I've written other implementations several other times during the intervening years, with gradient factors thrown in.

Anyone with a college engineering degree should have enough of a math background to understand a Suunto.

VPM is a bit harder, but it isn't string theory. RGBM is impossible simply because its a trade secret.

 

[gasgirl]

I think that's basically a true statement but its misleading...

Hey lamont! You must have ESP along with your superior engineering skills cuz I was just trying to figure out how to PM you when you posted your response.

Did you realize you were the one who originally posted the statement in a 2007 thread titled "Doing Light Deco as a Recreational Diver" :shocked2:

 

[pasley]

"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!

Short clear concise answer: NO. I would not do that dive and I would not recommend it.

As others have pointed out, your computer takes all variables of the dive you are actually doing (depth and time at each depth, previous dives in the past 24 hours etc) to compute your remaining NoDecompression Limit (NDL) for that dive.

What you are talking about is Technical diving.Technical diving requires precise planning and precise execution. This planning and execution is more than just doing a minute or two at 60, 40 and 15 feet.

Bottom line you and your dive buddies should plan (and execute the plan) to be on the surface before any diver in the group exhaust their NDL. If that means they miss 5 minutes of a dive that their dive computers say they can do, tough nuggies. That is the way it goes. To try to do a "Gee I hope the computer clears my deco before I surface" dive is not wise.

Bottom line, what do you gain by going past NDL and hoping it clears? A few more minutes of bottom time? Seriously, is that really worth the risk? After all what is the worst that could happen? Out of Air?A trip to the chamber? Paralyzed for life or dead? But hey, you squeezed a few extra minutes out of the dive. Not woth it.

 

[gasgirl]

Now that the original person who posted the statement has elaborated on the answer, I guess the matter is closed.

Thanks, lamont, for speaking up in such a timely manner... (I think there was the start of a lynch mob forming ).

Thank-you all for taking time to respond to my question about the Suunto algorithm.