PDA

View Full Version : Suunto's conservatism comparisons



Aussie
11-26-2007, 22:09
I noticed that alot of people state that they didn't like the Suunto computers as they are too conservative. No one really could explain how conservative they are.

On my recent trip to Vanuatu to dive the USS President Coolidge, I decided to double check the conservatism of my Suunto computers (D9,Vytec) against my old Aladin pro backup (as the Aladin known to be more aggressive).

I was doing two dives a day all of which were deco dives. The range in depth was from 40m (130fsw) to 64m (210fsw). Safety stops were done at 12m,9m,5m. Most dives were for a minium total time of 60min.

The Aladin was clearing its deco time on avergae 5-6minutes before the Sunnto's.

Given that the diving I was doing was well outside the recreational limits and doing decompression dives on every dive it show that the difference was only minor.

I would of like to have taken a Oceanic/Aeris computer for a further comparison.

Aussie

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-26-2007, 22:27
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

Soonerwink
11-26-2007, 22:30
My dive buddy dives an Oceanic veo 180 and I dive a Suunto vyper. We don't do deco dives and our computers are never more than a couple of min. different.

Aussie
11-26-2007, 22:43
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

I agree BouzoukiJoe,

What kind of dives are these people doing when they say "I get so much more bottom time with brand x compared to brand y"?

I believe that the conservatism of the Suuntos would be alot safer when preforming deco dives like I did. This is where the surface is your enemy and more time under the water the better it is for you.

Aussie

Mtrewyn
11-27-2007, 01:21
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

I agree BouzoukiJoe,

What kind of dives are these people doing when they say "I get so much more bottom time with brand x compared to brand y"?

I believe that the conservatism of the Suuntos would be alot safer when preforming deco dives like I did. This is where the surface is your enemy and more time under the water the better it is for you.

Aussie

:smiley32: This sounds like the voice of reason to me. :smiley20:

Zenagirl
11-27-2007, 07:03
I don't choose to dive a Suunto because my computer is well within the recreational dive limits and there is no evidence whatsoever that diving a Suunto is safer. I can make my computer more conservative if I choose or dive it a little more aggressively, but still well within the NDLs.

If I were regularly diving deco profiles, I'd likely be looking at a Uwatec or Dive Rite computer.

Just my preference.

ianr33
11-27-2007, 09:22
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

I like my Aeris computer for its flexibility. Surface in the green and it is fairly conservative.Surface high in the yellow and it is aggressive.

I have only ever done a couple of dives when I surfaced with it in the yellow but I felt pretty beat afterwards.

Do the deco/safety stops that are right for you,not your computer.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 09:55
... Everyone who uses a dive computer is part of an uncontrolled experiment. We are all really guinea pigs for the computer manufacturers.

Especially when we are doing saw-tooth or inverted profiles and relying on the computer's decompression model instead of the data from the decompression studies. This data comes mainly from normal square profiles with deepest dive first. In effect, we are providing the data to validate (or not) the models that the computers use.

I am not saying that the computers that use other models are wrong but the Reduced Gradient Bubble Model makes sense to me. I am not a diving physiologist but I did my engineering thesis at the MIT fluid mechanics lab studying the effects of fluid shear on human endothelium so I am not a total moron when it comes to evaluating these sorts of things.

FWIW, I am able to change a constant in the RGBM to make it more agressive if I wish. At 41 years old and a taste for beer I don't choose to do this.

Navy OnStar
11-27-2007, 10:45
I agree with the conservatives here. I will sacrifice a few minutes of bottom time to reduce the risk of getting bent. That was the whole reason I went with Suunto and I changed some of the setting to actually reflect ME and made it a little more conservative.

I'm not saying anybody is right or wrong but it doesn't make sense to me to try to push an envelope that not everybody agrees is THE envelope. Until it comes out that this is the way everybody reacts every day to depth and here is the model to use (which will never happen) - I'll stay with the conservative.

OnStar

wheelman
11-27-2007, 10:50
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

I agree BouzoukiJoe,

What kind of dives are these people doing when they say "I get so much more bottom time with brand x compared to brand y"?

I believe that the conservatism of the Suuntos would be alot safer when preforming deco dives like I did. This is where the surface is your enemy and more time under the water the better it is for you.

Aussie

I also agree... I dive with a vyper because I like the conservatism.

mm2002
11-27-2007, 10:53
I would rather have a conservative computer, who wouldn't?

ianr33
11-27-2007, 10:58
I would rather have a conservative computer, who wouldn't?

Me :smiley36:

You dont have to dive an aggressive computer to its NDL

You can always do a longer safety stop than an aggressive computer is asking for,but you cant unbend a violated conservative one.

(Well,if it has user replaceable batteries you can )

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 11:50
Good point.

I was playing with my Suunto and accidentally left it in gauge mode. I got in the pool to get my weight right for a new bottle. The thing locked me in gauge mode for 48 hrs when I had some nitrox dives coming up the next day. Bummer. I had to remove the battery to reset it so I could use the computer features. I had to dive with a computer that could have been leaking.

I understand why they did that but that is the only time I have regretted Suunto choosing to err on the side of conservatism.

Puffer Fish
11-27-2007, 12:12
What I have seen with suunto's calculations is not so much a different set of numbers, but using long time bites to do the calculation. I don't remember the model, but it was using the deepest depth, over a 30 second time frame, versus the oceanic which was every 1 or 2 seconds. If doing a square profile, they came out almost the same... doing lots of small ups and downs (like lobster hunting) and you get very different numbers.

I don't know if this is true with all suunto products... or just the one my friend had. I do know that she was using the default setting.

Given that difference, I am not a Suunto fan, but I don't know if they all are that way. but I tend to dive a very conservative profile anyway...

Puffer Fish
11-27-2007, 12:15
I would rather have a conservative computer, who wouldn't?
dive tables.. they are really conservative... I would prefer accurate calculations. I can dive as conservative as I want, as long as I know the consistency of the calculation.

BSea
11-27-2007, 12:20
I've used both an Oceanic & now have a Suunto. I havn't noticed any less bottom time. I'm sure there is a difference, but not that a sport diver will notice. For multiple day dives, I usually don't complain about a few less minutes underwater. When you make 2, 3, or even more dives per day on multiple days, what's a few minutes?

My 2 is that you should buy what you think is right for you, and that you can get easily serviced.

Mtrewyn
11-27-2007, 12:28
I agree with the conservatives here. I will sacrifice a few minutes of bottom time to reduce the risk of getting bent. That was the whole reason I went with Suunto and I changed some of the setting to actually reflect ME and made it a little more conservative.

I'm not saying anybody is right or wrong but it doesn't make sense to me to try to push an envelope that not everybody agrees is THE envelope. Until it comes out that this is the way everybody reacts every day to depth and here is the model to use (which will never happen) - I'll stay with the conservative.

OnStar


Again the voice or reason, why push for just a couple of minutes?

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 12:43
I don't know about all models but mine has an adjustable sampling rate: 1, 10, 20, 30, or 60 seconds. 20 seconds is the default.

Aussie
11-27-2007, 15:17
I don't know about all models but mine has an adjustable sampling rate: 1, 10, 20, 30, or 60 seconds. 20 seconds is the default.

My Two Suunto's have the same adjustable sampling rates. I think there is an issue if your recording your data in your computers log section. The amount of detailed log information is reduced when a higher sample rate is used. Not so important when your downloading your data every couple of days, but it will be an issue after a weeks diving or a liveaboard trip.

Aussie

Aussie
11-27-2007, 16:46
There is however plenty of evidence that diving within your computers NDL will not guaranty that you won't get a DCS hit. In fact many rec. divers that get bent are well within their computers NDL. Everyone who uses a dive computer is part of an uncontrolled experiment. We are all really guinea pigs for the computer manufacturers.

Anyone who thinks they can dive any computer on the market aggressively to the edge of it's NDL & can't ever get bent is kidding themselves. Also the deeper your dives, or the longer your dives, or the older you are puts you at greater risk of an undeserved hit.

I agree,

I feel that we too are guinea pigs to the computer manufacturers. With their closely hidden algorithms and no industry standards.

The common comment of "I choose my computer because it gives me 10 minutes more NDL than my buddies" is not the best example for new divers looking at buying a dive computer. Even more so when you add in other factors like which a computer does not:

physical condition of the diver (ie over weight, injuries)
age of the diver
amount of dives the diver does (are they one a year or once a day)
dehydration of the diver at the time of the dive
task loading at depth (are they working themselves at depth)
type of profile the diver performs (zig-zag profile, square, gentle slope on assent)
thermal protection of the diver (has the dive got enough wetsuit/drysuit for the conditions)
water temperature
alcohol/drug use prior to diving
Diving location (tropics or cold waters)
So an experience diver who is 50 years of age, which due to work can only do a liveaboard for a week once a year. He/She is overweight due to their desk job and has a couple of old sports injuries from when they where younger.
They are on a liveaboard for a weeks diving holiday and the night before they had a few drinks to relax and get into their holiday mode. They have left their own wetsuit behind in the mad panic of packing for the trip and had to use a hire suit which does not fit them correctly as they are an odd size (big bum).
They sleep in and turn up late for the first deep morning dive. They didnt get a chance to have a nice long drink of juice or water and are feeling a little dehydrated. Especially when they are diving in the tropics and its very humid.
They are now in the very warm tropical waters doing a drift dive along a reef wall. Water temp is 29c/85f which is great as the hire suit doesn't fit, but its warm even down to 30m/100f. Suddenly a cold thermocline rolls in and the water temp drops to 21c/70f. Now their buddies tanks band has come undone, so they have to wrestle the tank back on.
Our experienced diver is great on their air so they rely on their dive computer (agressive) more than air consumption. The NDL is getting to about 5min so our experience decides to slowly head up to shallow waters as they are also getting cold and have a headache. They do the required safety stops which their computer has indicated. They get back onboard after a nice long dive and are little on a the cold side. They have a nice mug of hot coffee and go up onto the sundeck to soak up some hot tropic rays.

At lunch time our experienced diver on his/her first day of diving is performing their first dry dive in the local decompression chamber.


This just shows how even when diving with any type of dive computer that there are so many other factors which the computer can not calculate into its algorithm and will put a diver into risk. There is levels of conservatism on most dive computers but again we are in the hands of the secret algorithms that manufacturers have locked away.

Some form of industry standard should be set so that this uncontrolled experiment be accountable.

Stating "I choose my computer as it gives me more NDL time and I want as much time underwater as I can" isnt the right message to be expressing to new divers and people in the market for a new computer.

In the end of the day the most important computer you have is your brain and use your dive computer as a tool for your brain. Maybe when we can see and compare each and every algorithm/dive computer thats when we will get a more accurate account of which algorithm /computer is most suited to the individual. Maybe like some Tech dive computers that the everyday computer will provide a different range of algorithms to choose from for different diving situations.

Aussie

Puffer Fish
11-27-2007, 16:52
I've used both an Oceanic & now have a Suunto. I havn't noticed any less bottom time. I'm sure there is a difference, but not that a sport diver will notice. For multiple day dives, I usually don't complain about a few less minutes underwater. When you make 2, 3, or even more dives per day on multiple days, what's a few minutes?

My 2 is that you should buy what you think is right for you, and that you can get easily serviced.
I've seen as much as 10 minutes a dive... which adds up on a 6 dive day...but don't think all profiles or computers have this big of a difference.

mcc2318
11-27-2007, 18:35
I'd rather be safe when it comes to dive computers whats a few minutes when it comes to your well being

CompuDude
11-27-2007, 18:57
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

Why not just return to the surface 10 minutes earlier, and increase your BT further? That would be safer still, right?

Personally, I'd rather be the one choosing to shorten my dive by a few minutes, than have my computer insist on doing so and lock me out should I make the informed choice to push things on a given dive.

Again, if someone could prove to me that Suunto has a better safety record (and you know Suunto would be the first to trumpet this if they could do so), then I'd be more interested in them. Meanwhile, given the safety record of all computer manufacturers and my preference for freedom of choice, I'll never recommend a Suunto (outside of gauge mode usage).

Interesting tidbit I heard recently. Suunto computers are very popular with DiveMasters on liveaboards as loaners, because they get them back on the boat a lot sooner.

Edit: Some actual testing and comparison of algorithms: Crunching the Numbers - Scuba Diving Magazine (http://www.scubadiving.com/gear/divecomputers/article3685/?m_nPage=2)

I'll see if I can dig up some more links, because I know there is at least one other article like this (but with more detail) that I've seen...

Charting the Differences (http://dive.scubadiving.com/images/200408GR_computer_charts.gif)

OTGav
11-27-2007, 19:13
Interesting tidbit I heard recently. Suunto computers are very popular with DiveMasters on liveaboards as loaners, because they get them back on the boat a lot sooner.



"Get them back on the boat sooner" sounds like a negative, one to make the DM's life easier, and get through the day quicker.

Loaners are more likely to be for occasional divers, and less familiair with the gear (not to mention fitness etc.)- surely reducing their bottom time by a couple of minutes, and sounding the alarm earlier if they do go outside the computers recomendations is a good thing, an easy margin of error to build in for them all, and an increase in saftey?

Not saying that DM's don't want a nice short day too :smiley2:

To be honest I would have thought that 9 times out of 10 it's air not bottom time that brings them back to the boat.

Puffer Fish
11-27-2007, 19:15
I like Suuntos because they are conservative. Why increase my risk of taking a hit for a couple more minutes of bottom time?

Thanks for posting.

Why not just return to the surface 10 minutes earlier, and increase your BT further? That would be safer still, right?

Personally, I'd rather be the one choosing to shorten my dive by a few minutes, than have my computer insist on doing so and lock me out should I make the informed choice to push things on a given dive.

Again, if someone could prove to me that Suunto has a better safety record (and you know Suunto would be the first to trumpet this if they could do so), then I'd be more interested in them. Meanwhile, given the safety record of all computer manufacturers and my preference for freedom of choice, I'll never recommend a Suunto (outside of gauge mode usage).

Interesting tidbit I heard recently. Suunto computers are very popular with DiveMasters on liveaboards as loaners, because they get them back on the boat a lot sooner.

Edit: Some actual testing and comparison of algorithms: Crunching the Numbers - Scuba Diving Magazine (http://www.scubadiving.com/gear/divecomputers/article3685/?m_nPage=2)

I'll see if I can dig up some more links, because I know there is at least one other article like this (but with more detail) that I've seen...

Charting the Differences (http://dive.scubadiving.com/images/200408GR_computer_charts.gif)

The differences are so big, it is hard to believe that both could be even close to being correct. Very odd..

OTGav
11-27-2007, 19:26
The charting the Diff link is pretty amazing.

Compairing one extreme of the chart to the other - incredible, I can see why some people do promote Suunto now - in the middle of the range, no extreme variences across the dives, a steady model under all conditions tested - same for the Tusa.

I guess the only arguments comes from if the left hand extereme of the chart is "safe", and all the others are just being more or less paranoid and conservative under certain conditions.

Puffer Fish
11-27-2007, 19:41
The charting the Diff link is pretty amazing.

Compairing one extreme of the chart to the other - incredible, I can see why some people do promote Suunto now - in the middle of the range, no extreme variences across the dives, a steady model under all conditions tested - same for the Tusa.

I guess the only arguments comes from if the left hand extereme of the chart is "safe", and all the others are just being more or less paranoid and conservative under certain conditions.
I think you have the issue correct, either one is paradoid, or the other dangerous... If they both have the same safety record.. then the answer is obvious... but I am not completely sure we know that answer. I dive scubapro, which is closer to oceanic than Mares, and choose to use the five minute rule.. I avoid DECO by at least 5 minutes. But I know a lot of Oceanic divers that push the limits... which somewhat surprises me they don't seem to have any issues, and they do it a lot.

I am also not sure that they are as far off as shown, as the real issue is what does it show, right before you begin to go shallower.. showing 70 minutes versus 20 in 20 ft of water is rather meaningless. I think most people use one to manage the "turning point"

Travelnsj
11-27-2007, 19:54
I don't know about all models but mine has an adjustable sampling rate: 1, 10, 20, 30, or 60 seconds. 20 seconds is the default.

My Two Suunto's have the same adjustable sampling rates. I think there is an issue if your recording your data in your computers log section. The amount of detailed log information is reduced when a higher sample rate is used. Not so important when your downloading your data every couple of days, but it will be an issue after a weeks diving or a liveaboard trip.

Aussie

Learned my lesson...forgot I had my sampling rate set at 10 seconds on my D9 and Corba....did about 40 dives between Bali and Wakatobi.....lost 12 dives....on my way to Lembeh Straits/Raja Ampat in three weeks....set my sampling to 20 seconds.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 20:02
I think you have the issue correct, either one is paradoid, or the other dangerous... If they both have the same safety record.. then the answer is obvious...

I think you answer this question yourself:


But I know a lot of Oceanic divers that push the limits... which somewhat surprises me they don't seem to have any issues, and they do it a lot.


In other words one can't be proven safer than the other because there are not enough observations. Diving within the NDL limits even on these computers is safe enough that there are not enough hits to say with confidence that there is a safety difference. At the same time we all *know* that your 5 minute rule is safer than pushing the limits. Just no statistical proof that it is so.

It's the same with diving Nitrox on the air tables. It's obvious that its safer (as far as DCS goes) but diving air within NDL is so safe that there are not enough observations to show it statistically with a high confidence level.

dannybot
11-27-2007, 20:49
[QUOTE=Aussie;98399]I noticed that alot of people state that they didn't like the Suunto computers as they are too conservative. No one really could explain how conservative they are.

Last summer, at Grand Cayman, I was diving a Gekko, my wife an Aeris XR1. We had nearly identical profiles, if anything, I hovered above her for most of the dive. Tha Suunto gave me a 13 min deco stop, and the Aeris gave her the standard 3 min.

The dive was, as I recall, rather sawtooth, since we were transversing coral fingers, and I had done one more dive the day before (which is why i stayed shallower than her). I posted this same question a while back, and the most informative response I got was to have a 75 min surface interval, which I maintained on our last trip. No further issues noted, so I will side with that bit of info. You can check what your computed bottom time will be before you dive, to check the adequacy of your SI.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 22:04
So I take it you ignored the computer's NDL time if you got into deco. I guess I'm too conservative to do that. Shadow Divers helped me learn to fear DCS. I do know that my Suunto does not like for me to make repeated ascents and descents.


One good feature is that the model allows for continuous decompression as you ascend. If I accidentally get into deco I sometimes find that my obligation is cleared during the ascent. I've only tried this in the simulator, never actually went into deco on a real dive.

Firefyter
11-27-2007, 22:23
I do know that my Suunto does not like for me to make repeated ascents and descents.

You are exactly right. I've been diving Suunto's for years, and if used correctly, they will give as much bottom time as most others. They HATE sawtooth profiles, especially when the changes are rapid, as they usually are. These computers like long, slow ascents, and when most people dive a sawtooth, they are changing fairly rapidly, even if it's for a few feet at a time. Then they drop back down, and back up another few feet, usually too quick. The thing is, most divers don't notice this like they would a normal ascent, but it's there nonetheless. You can keep these computers happy by ascending veeeeerrrry slooooowly, which is better for you in the long run. I usually ascend one foot at a time, pausing at each foot for a couple of seconds or more. I'm always the first in the water, last one out.



One good feature is that the model allows for continuous decompression as you ascend. If I accidentally get into deco I sometimes find that my obligation is cleared during the ascent. I've only tried this in the simulator, never actually went into deco on a real dive.

I have deliberately gone into deco several times, with prior planning, and it works just like in the simulator. Depending on the deco obligation, it will sometimes clear on the ascent. Other times, you may have to hang at a specified depth for a while to clear it. The key is to make sure you have enough gas to fulfill the obligation.

Travelnsj
11-27-2007, 22:38
I have also gone into Deco a few times with my Suunto's....it is very important to make sure you have enough O2 for that obligation....once I could not fulfill my 15 minutes...the last 2 minutes...suffered with a computer in gauge mode for a couple of days.

PsychDiver
11-27-2007, 22:58
I have a Suunto Cobra2 and a Oceanic VT3. I will do some comparisons and post the findings.

CompuDude
11-28-2007, 02:43
I don't believe that the Suunto or Mares use a true implementation of RBGM theory in their algorithm. Consider this; deep stops to prevent micro bubble build up are a part of the RGBM theory. In the first iteration of the above makers of RGBM computers there are no deep stops. In the second/current iteration there are deep stops, but you can turn them off. Of course I'll never know for sure (proprietary code & all that) but think they're more likely to be a neo Haldanean base with a lot of tweaks, hacks & fudges to get something similar to an RGBM outcome.

In poking around the net looking for info for my post, up above, I came across more than one reference to this, actually.

The gist was that Suunto's computers are Handane models as well. The difference is some RGBM limiting factors folded over the usual models. If you want a TRUE RGBM computer you need to buy something like the HS-Explorer.

Apparently, on simple NDL profiles Suunto's times are pretty close, but once you get into mandatory decompression stops Bubble models (VPM, FULL - RGBM) tend to get you out of the water quicker and in some case A LOT quicker. The blurb went on to say Suunto's computers actually bend long before the true RGBM models do, as shown by deco students carrying Suunto's along with them while diving RGBM tables. The Suunto's wanted a LOT more deco than the actual tables.

I'd be very curious to test this myself... but I'm not interested in owning Suunto computers enough to take the time. :smiley36:

Zenagirl
11-28-2007, 08:40
What a great discussion!!

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-28-2007, 08:57
I don't know, first CD commits sacrilege with a constant stream of scurrilous comments about the transpack. Then he attributes my work to someone else. Well, I'm not going to take it anymore. I'm going straight over to the flame wars thread & give him hell. :smiley29:

I almost spewed my coffee when I read this. :smilie39:

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-28-2007, 09:09
The gist was that Suunto's computers are Handane models as well. The difference is some RGBM limiting factors folded over the usual models. If you want a TRUE RGBM computer you need to buy something like the HS-Explorer.

Apparently, on simple NDL profiles Suunto's times are pretty close, but once you get into mandatory decompression stops Bubble models (VPM, FULL - RGBM) tend to get you out of the water quicker and in some case A LOT quicker. The blurb went on to say Suunto's computers actually bend long before the true RGBM models do, as shown by deco students carrying Suunto's along with them while diving RGBM tables. The Suunto's wanted a LOT more deco than the actual tables.

I'd be very curious to test this myself... but I'm not interested in owning Suunto computers enough to take the time. :smiley36:

Interesting post. Clearly doing more deco is safer. Maybe unnecessarily conservative. I'm not qualified to say. Maybe after I get in another year of NDL diving and feel ready to try planned deco, I'll want to switch to another computer. Maybe not. I'll see how I feel about it at the time. For now, the Suunto is working just fine for me.

Puffer Fish
11-28-2007, 09:21
The gist was that Suunto's computers are Handane models as well. The difference is some RGBM limiting factors folded over the usual models. If you want a TRUE RGBM computer you need to buy something like the HS-Explorer.

Apparently, on simple NDL profiles Suunto's times are pretty close, but once you get into mandatory decompression stops Bubble models (VPM, FULL - RGBM) tend to get you out of the water quicker and in some case A LOT quicker. The blurb went on to say Suunto's computers actually bend long before the true RGBM models do, as shown by deco students carrying Suunto's along with them while diving RGBM tables. The Suunto's wanted a LOT more deco than the actual tables.

I'd be very curious to test this myself... but I'm not interested in owning Suunto computers enough to take the time. :smiley36:

Interesting post. Clearly doing more deco is safer. Maybe unnecessarily conservative. I'm not qualified to say. Maybe after I get in another year of NDL diving and feel ready to try planned deco, I'll want to switch to another computer. Maybe not. I'll see how I feel about it at the time. For now, the Suunto is working just fine for me.
The problem is.. there are a lot of experts out there, but it is sort of like sleeping in a library.. sure you are near really important stuff, but that does not mean you know it.

We have the technology to determine the size and amount of bubbles formed from following any "plan", yet I don't see a lot of detail or tests that show why one is better than another, and just looking at the statistics does not seem to show much. Yet, there seems to be "camps" of people that believe one is great.. another terrible... wish there was far more hard facts on this issue.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-28-2007, 09:51
We have the technology to determine the size and amount of bubbles formed from following any "plan", yet I don't see a lot of detail or tests that show why one is better than another, and just looking at the statistics does not seem to show much. Yet, there seems to be "camps" of people that believe one is great.. another terrible... wish there was far more hard facts on this issue.

Agreed. There is a definitely a lack of hard facts on this issue.

Grin
11-28-2007, 10:34
I got a slight case of the Bends a few years back. Diving a Oceanic data plus. I don't really blame the computer or it's logrithym. I was well within NDL when it happened. I adjusted other items in my dive profile and feel better then ever after a days diving these days. The biggest thing I changed is my accent speed. I went from the 20-30ft per mnute accent that everyone says is so safe/and your computer is programmed to indicate, to 10 ft per minute(or less) once I get to 60 ft(10-15 FPM below that). For deep divers this may not be a legitamate option, but I rarly see over 90-100 ft so it works great for me. I dive 1.3-1.4 PO2 mixes of Nitrox(35-38 mix) and my accent now takes 10 minutes vs the 4-5 it used to take. I now do the full 3 min safety stop to go from 20-15 ft, and then I accend that last 15 ft at 10 FPM or slower. Every once in awhile I might see a yellow caution bar on my Nitrogen display on my computer. As soon as that happens I'm done and starting my accent. Actually it's rare for me to see a Yellow bar, but I'm not afraid of it. I routinly do 50 minute dives to 70-85 ft. So my bottom times are easily over 1/2 hour in 70-80 ft which is very good for my liking.
There are so many variables to consider for DCS, a computer logrythim is not what I think is the most important thing. You have to add in all the mitigating circumstances like: cold, over exertion, nitrogen loading, depth, repeat dives and on and on.
Anyway, I know the extra 5 minutes added to accend, I now take, made a huge difference for me. I feel like million bucks at the end of the day. So often all my dive buddies are beat and dragging to get home and chill. That used to be me. This really was a non expected bonus to me as I knew if I were to continue to dive(after my case of DCS) I needed to take every option of conservatism. The result was, I now feel safer, and I also feel so supreme at the end of a days diving. That gave me the confidence to continue diving.
I came up with this super slow accent idea after reading some Duke univertisty/DAN tests they did on accent speed and the resulting bubble formation tests results. It was very apparent that slow accents resulted in less bubbles. They even described some super slow accents as "no detectable bubbles". I am no expert by any means, but I took that and ran with it, and I can 100% gaurantee that I never feel any residual effects from diving like I very commonly did before I changed my style. I actually feel better and livelier after a days diving, which is how it is supposed to be in a perfect world. A meager 5 minutes added per dive changed everything in diving for me.
I still see many people at the end of the day with symptoms that I personally call DCS. They call it a headache, or many other denial type symptoms and silly diagnosises. I used to be in denial also. I had the most common symptom to DCS of a shoulder pain, and I denied it. I wrote it off as old age pain. I was 100% an idiot and in denial. I got a DCS hit and still denied it for awhile and finally called DAN and went to a dive doc where they set me straight. I thought I had a ear issue, but it was definatly a bubble(DCS).
My little way of thinking about how to control DCS is twofold. 1. Accending slow bleeds bubbles off and keeps bubbles from forming. 2. Nitrogen buildup is the other one that gets all the attention. Obviously dive time, offgassing at safety stops, and time between dives is the way we control that.
It seems the bubble control aspect is the one many seem to forget about.
And don't forget about that last 20 ft of your accent. Many consider that the most important part(I do now). Many do their safety stop and fly up that last 20 ft. I claim that's not a good idea.
I also make 100% positive to do a super precision slow accent for my last dive of the day, maybe even adding another 2 minutes into it for good measures.
Look at it this way: A correct accent from 80 ft at 25 FPM is going to take you 6 minutes including your 3 min stop. Add 3 -4 minutes to that is all I did. That is virtually nothing. And doesn't take hardly any more gas to accomplish either. Consumption rate at above 60 ft is minimal. My way probably takes 100 Cu ft more than my old way.
I'm convinced! Others can do what they choose. To me the part about feeling better aftrer diving 100% of the time is a benfit I didn't even know existed. It's well worht it to me. I'm sure many have zero issues and scream to the limits of their computers. That's fine with me. I definalty know I see many people who seem rather tired at the end of the day alonfg with other symptoms. I know for a fact many need to adust their style, but that's up to them. A minor change of style and couple minutes, might change everything for these people who race and max everything then pay the price.
You see them race to the bottom, burning all over the place while down there, and then fly to the top, but at the dock I win in the end. And it's well worth it because that's what really counts.
I have a Oceanic VEO 250 for what it's worth.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-28-2007, 11:43
Thank you for sharing. I used to feel tired and/or have headaches after my dives when I was using tables. After I switched to the Suunto I no longer have this issue. I think its because I now ascend slower and make deep stops. The Suunto model seems to reward that (or at least punish the opposite). Don't know about the other computers. Main point is ascend slowly to give your body time to off gas whether you are using tables or a computer of any type.


I like to think of my body like a 2 liter bottle of coke. Moving up and down, expending effort, shivering etc. is like shaking the bottle. Ascending is removing the cap. The more shaken the bottle the slower you need to bleed the pressure to avoid spewing.

CompuDude
11-28-2007, 12:25
I don't know, first CD commits sacrilege with a constant stream of scurrilous comments about the transpack. Then he attributes my work to someone else. Well, I'm not going to take it anymore. I'm going straight over to the flame wars thread & give him hell. :smiley29:

:smilie39:

Sorry, quotes fixed. (the proper attribution was in there, but ignored by the board software...)

Flame on! :smiley2:

in_cavediver
11-28-2007, 18:24
The gist was that Suunto's computers are Handane models as well. The difference is some RGBM limiting factors folded over the usual models. If you want a TRUE RGBM computer you need to buy something like the HS-Explorer.

Apparently, on simple NDL profiles Suunto's times are pretty close, but once you get into mandatory decompression stops Bubble models (VPM, FULL - RGBM) tend to get you out of the water quicker and in some case A LOT quicker. The blurb went on to say Suunto's computers actually bend long before the true RGBM models do, as shown by deco students carrying Suunto's along with them while diving RGBM tables. The Suunto's wanted a LOT more deco than the actual tables.

I'd be very curious to test this myself... but I'm not interested in owning Suunto computers enough to take the time. :smiley36:

Interesting post. Clearly doing more deco is safer. Maybe unnecessarily conservative. I'm not qualified to say. Maybe after I get in another year of NDL diving and feel ready to try planned deco, I'll want to switch to another computer. Maybe not. I'll see how I feel about it at the time. For now, the Suunto is working just fine for me.
The problem is.. there are a lot of experts out there, but it is sort of like sleeping in a library.. sure you are near really important stuff, but that does not mean you know it.

We have the technology to determine the size and amount of bubbles formed from following any "plan", yet I don't see a lot of detail or tests that show why one is better than another, and just looking at the statistics does not seem to show much. Yet, there seems to be "camps" of people that believe one is great.. another terrible... wish there was far more hard facts on this issue.

I personally prefer the Buhlmann algorithm with some form of deep stops added, be it pyle, gradient factor or whatnot. My computer does Buhlmann with Pyle stops.

The reason for my choice is twofold. First, its a well established model with good data backing it up, including the 'bent' divers modifications. Its not perfect and there are a lot of the add-ons to make it better. Second, its the model I have used as I went from NDL to whatever I fell like diving. I have personal experience with my body doing these dives and the mods to make my dives great.

Just before I started tec training, I had done lots of deepish repetitive dives with the quick to 15' ascents and was beat after a day. 9 months later, after 8 hours in the truck getting up at 5:00 AM, I did a dive to 150' for 30 minutes, used Buhlmann with GF and felt BETTER getting out of the water than I did getting in the water. O2 is a great thing.
This personal knowledge/experience is hard to beat.

dannybot
11-29-2007, 21:58
I was playing with my Gekko and my wife's XR1 last night, and did some comparisons in the plan mode. I found that I get the same time for bottom times (essentially), if I put the Gekko on nitrox at 24%. This is only comparing the plan for the two, it does not take into account any other factors like ascent rate or profile.

CompuDude
11-29-2007, 22:48
I was playing with my Gekko and my wife's XR1 last night, and did some comparisons in the plan mode. I found that I get the same time for bottom times (essentially), if I put the Gekko on nitrox at 24%. This is only comparing the plan for the two, it does not take into account any other factors like ascent rate or profile.

One one dive, there's very little difference. On multilevels dives over multiple dives over multiple days, the differences add up staggeringly quick. Since planners don't usually let you forecast 2-3 dives in advance, the differences aren't immediately apparent.

dannybot
11-30-2007, 19:41
I was playing with my Gekko and my wife's XR1 last night, and did some comparisons in the plan mode. I found that I get the same time for bottom times (essentially), if I put the Gekko on nitrox at 24%. This is only comparing the plan for the two, it does not take into account any other factors like ascent rate or profile.

One one dive, there's very little difference. On multilevels dives over multiple dives over multiple days, the differences add up staggeringly quick. Since planners don't usually let you forecast 2-3 dives in advance, the differences aren't immediately apparent.

Yea, I knew it was a limited look, it simply implies that there is a difference in the two.