Suunto Vyper vs Uwatec Galileo algorithm

[Hatul]

On my recent trip to Cozumel my Vyper locked out for 48 hrs after surfacing from the second dive of the day.

The first dive was to Palancar Caves, a 51 minute dive with max depth of 95 ft and ave depth 49 ft. The surface interval was rather short 47 minutes and the Vyper took revenge on me on the second dive. The attachments show the dive profile of the second dive from Suunto Dive Manager/Uwatec SmartTrak side by side. The first photo is at 26 minutes and the second photo is at 46 minutes into the dive:



The second dive was Dalila: 61 min dive, max depth 67 ft, ave depth 39 ft. At 26 minutes into the second dive the Vyper is in deco with ceiling of 10 ft and ascent time of 3 minutes, while the Galileo shows 13 min no deco time.
At 46 minutes the Vyper has deco of 11 minutes ascent time from depth of 25 ft, 10 ft ceiling. The Galileo here shows 199 minute no deco time.
To make long story short the Vyper continues in deco while is Galileo shows almost unlimited no deco time.
I ended up doing a 6 minute safety stop, but the Vyper still had deco of 5 minutes of ascent time after this and I surfaced nevertheless, at which point the Vyper went into error mode and locked out for 48 hrs.

After this experience I would avoid Suunto computers as I'm convinced my profile was perfectly safe and it was not reasonable to lock out for two days.

 

[Hatul]

I think I have an understanding of what happened here. If you look closely at the screenshots of the Dive Manager profile from the Vyper, right on the initial descent there is violation symbol-- a triangle with an exclamation mark inside. This has been discussed on Scubaboard before and is always there if the SI is less than one hour. Subsequently the Vyper shortens the no deco times as I found and put my dive into deco.

I'm not sure if this holds for other newer Suunto computers, but at least for the Vyper it's important not to dive until the SI is at least one hour.

 

[LowVizWiz]

I'm glad you found the answer to your issue with the Vyper.
I won't debate the conservatism issue as that horse has been beaten to death many times over.
I will simply point out that the computer did exactly what it was programmed to do.

From the Vyper manual section 3.2.5 on Decompression Diving

DISPLAY ABOVE THE CEILING If you ascend above the ceiling, a downwardpointing arrow will appear and a continuousbeeping starts (Fig. 3.19). In addition, anerror warning Er reminds you that you haveonly 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 goes into a permanent ErrorMode. In this mode the instrument can only beused as a depth gauge and timer. You must notdive again for at least 48 hours (see also section3.8. “Error Conditions&#8221.

This is typical of any recreational dive computer in the case the diver violates the parameters in which the computer is designed to work, and I'm left trying to figure out what is it that you are trying to say?

 

[Hatul]

I'm glad you found the answer to your issue with the Vyper.
I won't debate the conservatism issue as that horse has been beaten to death many times over.
I will simply point out that the computer did exactly what it was programmed to do.

From the Vyper manual section 3.2.5 on Decompression Diving

This is typical of any recreational dive computer in the case the diver violates the parameters in which the computer is designed to work, and I'm left trying to figure out what is it that you are trying to say?

Thanks for your response. I have no problem with conservative algorithm and I have my Galileo Sol now set to MB level 2 (on a scale of 0-5) and include the deep (PDIS) stops. The issue I have is this: if your surface interval is less than 1 hr the Vyper shows a violation at the start of the dive apparent on the DM software, and then severely limits your non-deco times, to the point that while my Galileo showed unlimited non-deco time the Vyper was in deco, at least at one time. Also this behavior of severely restricting the non deco times and showing a violation is not documented anywhere in the manual that I could see.

As far as locking out for 48 hrs, I'm not sure your statement is correct. I don't believe the Galileo locks out. The combination of undocumented severe conservatism and 48 hour lockout on violation can spoil your dive vacation if you don't dive with another brand computer as well.

I'm not sure if this behavior is limited to the old Vyper or to the newer Suuntos as well. Perhaps someone with a Zoop or other newer Suunto can comment on the SI issue.

 

[EL Pistoffo]

I too would be very interested to know if the new Zoop has this issue as I just received two new Zoops. I probably wont be putting them to use till May.

It seems strange that you would get a violation on descent simply for the 47 min SI.

 

[LowVizWiz]

The issue I have is this: if your surface interval is less than 1 hr the Vyper shows a violation at the start of the dive apparent on the DM software, and then severely limits your non-deco times, to the point that while my Galileo showed unlimited non-deco time the Vyper was in deco, at least at one time. Also this behavior of severely restricting the non deco times and showing a violation is not documented anywhere in the manual that I could see.

You are correct, the manual does not mention that your bottom time will be greatly reduced during repetitive dives where the first dive comes close to the suunto NDL if the SI is under one hour. However, (I'm really not trying to argue with you, I actually understand your frustration) if you had entered into the computer your plan for the second dive with your current SI it would have told you precisely how much bottom time you would have before entering deco.

My beef with people who usually complain about the conservative nature of suunto computers is that usually they want to jump in and out of the water and have the computer tell them they are ok after the fact. Rather than planning their bottom times and being informed before the fact. I'm not saying that's your case, I'm just pointing out that the typical rec. diver does not take time to plan their dives properly then gripe about how the computer sucks.

Did you have enough gas to do an extra 5-8 minutes at 15'?

As far as locking out for 48 hrs, I'm not sure your statement is correct. I don't believe the Galileo locks out. The combination of undocumented severe conservatism and 48 hour lockout on violation can spoil your dive vacation if you don't dive with another brand computer as well.

I don't own a Galileo nor have I read its' manual, but I can assure you that most recreational dive computers will lock you out if you ignore their deco obligations. Also, the 48 hr lock out is documented on the suunto manual.

Why use different types of computers as a back up? If you must use different computers because that's all you got the diver should understand that different computers track NDL times differently and plan the dives using the most conservative of the two as not to bend the back up.

I'm not sure if this behavior is limited to the old Vyper or to the newer Suuntos as well. Perhaps someone with a Zoop or other newer Suunto can comment on the SI issue.

I've used 4 different suunto computers a Cobra, Vyper, Vytec and currently a Vyper Air and they all give you reduced bottom times during repetitive dives if the SI is under 1 hr. and the previous dive approached the suunto NDL.

 

[Hatul]

You are correct, the manual does not mention that your bottom time will be greatly reduced during repetitive dives where the first dive comes close to the suunto NDL if the SI is under one hour. However, (I'm really not trying to argue with you, I actually understand your frustration) if you had entered into the computer your plan for the second dive with your current SI it would have told you precisely how much bottom time you would have before entering deco.

My beef with people who usually complain about the conservative nature of suunto computers is that usually they want to jump in and out of the water and have the computer tell them they are ok after the fact. Rather than planning their bottom times and being informed before the fact. I'm not saying that's your case, I'm just pointing out that the typical rec. diver does not take time to plan their dives properly then gripe about how the computer sucks.

Did you have enough gas to do an extra 5-8 minutes at 15'?



I don't own a Galileo nor have I read its' manual, but I can assure you that most recreational dive computers will lock you out if you ignore their deco obligations. Also, the 48 hr lock out is documented on the suunto manual.

Why use different types of computers as a back up? If you must use different computers because that's all you got the diver should understand that different computers track NDL times differently and plan the dives using the most conservative of the two as not to bend the back up.



I've used 4 different suunto computers a Cobra, Vyper, Vytec and currently a Vyper Air and they all give you reduced bottom times during repetitive dives if the SI is under 1 hr. and the previous dive approached the suunto NDL.

Yes I had plenty of air and could have completed the deco stop required of the Vyper, 5 minute ascent time with 10 ft ceiling. I surfaced because I was convinced it was safe -- I was mainly following my Galileo and using the Vyper for backup. The Galileo showed unlimited no deco time and I had doubled my safety stop to 6 minutes. Also I was holding up the boat as everyone else was back on the boat. I confess at the time I did not know the Vyper would lockout for 48 hrs; had I known that I would have stayed the extra few minutes. When I got back to my room I looked up the "Er" display in the manual and realized the Vyper was finished for the rest of the vacation.

Why use the Vyper for backup? It's not the wisest choice-- better to use the same or more liberal algorithm for backup. The Vyper was my previous computer before I bought the Sol, so I used what I had.

---------- Post added March 25th, 2014 at 05:39 PM ----------

I too would be very interested to know if the new Zoop has this issue as I just received two new Zoops. I probably wont be putting them to use till May.

It seems strange that you would get a violation on descent simply for the 47 min SI.

Yes, this issue has been discussed on Scubaboard before:

Suunto "violation" [Archive] - ScubaBoard - Scuba Diving Forum - Diving Social Network

You need at least one hour SI if there is any significant nitrogen loading on the following dive.

 

[KeithG]

Golden rule for suunto owners: always have at least 1 hr SI regardless of your profile. Does it make sense? Not always.

And make sure you do not rush up the boat ladder either.

I have seen suunto divers locked out on live aboards due to a fast ascent violation while ascending the ladder. Probably from swinging their computer wrist from their knees to their shoulder as they climb the ladder. Happens so often that dealing with this computer behavior is now part of the boat briefing if anyone has a suunto.

Suunto has a few algorithm quirks that just do not make any sense at all.

If you understand them, you can work around them. If you do not, then you get severely punished. I will never own one.

 

[LowVizWiz]

I have quite a few dives with an SI of less than 45 minutes and I know beforehand depending on my gas choice and planned depth how much NDL I will have. I also know if I will need to exceed my computer's NDL based on the planned dive duration and adjust accordingly.

For example:
As you experienced, you had the gas to complete the dive. And most likely you knew this going in.

If at 46 minutes you had ascended to 20' instead of 25' would you have missed anything?

And if you had continued to dive for the next 15 minutes at or slightly above 20' your deco obligation would have been cleared by the time everyone else was ready to exit the water without you computer being bent.

I hope this is helpful.

 

[KeithG]

I think the key issue here is that suunto will punish you if you splash before its recommended SI is up. Other dive computers just calculate NDL based on your actual SI. They do not apply any extra penalty.

It would be interesting to find out if there was any science upon which the extra penalty was based. Seems like it is just an arbitrary design decision.