Need suggestions about budget dive computer

[stuartv]

Can you show an real example of this variation given normal diving practices. All you are doing is regurgitating information or miss-information with no actual understanding.
...

Please can you stop with the misinformation.

Go get certified, enjoy diving and build some real knowledge through experience.

I already posted a link in this thread, to a sticky'ed thread in this forum, with a table showing the Oceanic and others giving an NDL of 57 minutes compared to the Suunto NDL for the same dive of "40 - 48" minutes. You really think I don't understand what that line in that table means? Is it not "a normal diving practice" to dive to 60' and stay there as long as 50 minutes? And if it's misinformation, I am not the one who posted it. Further, no one in that (reasonably long) thread disputed the data in that table, so I'm skeptical that it is "misinformation".

It's nice that you and Lorenzoid have more conservative computers and you don't have an issue with the dive time you get. But, why do you feel like it's okay to use your personal dive habits and preferences as assumptions about what other divers are doing or going to do? You tell us that you have no issue with your Mares and Lorenzoid has no issue with his Suunto, implying that one of those should be good enough for anyone. Well, instead of implying that no one should have an issue with limiting their dives to as short as what you do, what is wrong with giving the OP the info about how the different computers work and let the OP decide what will be best for him or her?

This whole thing is really simple. The OP asked about budget computers, including listing some specific ones being considered. I made the observation that Suunto seem to be more limiting than other brands on bottom time. I have posted a link to a thread with data that supports my statement. I also stated that that data is A reason (but not the only reason) why I have removed Suunto from my own personal shopping list. And I have been attacked relentlessly for it. Where is the error in what I said?!? Some of you are acting like I called your baby dumb and ugly! If you cannot refute the data posted, using other data (not anecdotes), apparently, you still feel a need to attack me by pointing out my inexperience in diving - as if my diving experience has something to do with the truth or falsity of the statements made about how these different computers work.

If someone posts a comment that the computer you use is more conservative than others, and the comment was made as providing data that a person might use as they see fit when shopping for a computer, and that irks you (as Lorenzoid said it does him), you need to either refute the data or get over yourself! Personally, I would LOVE to see more actual data on the subject, so if you have some PLEASE post it. If you don't have anything more useful to say than "I use XYZ and it almost never limits me," well, I don't see how you're actually helping the OP or anyone else.

I suspect you and several others have developed an opinion of me that I am some kind of idiot and you expect that I'm going to be the kind of diver that you would never want to dive with. To that I say: I am a very experienced motorcyclist. I have even won several roadracing championships. And if you ask anyone that rides with me, I think they will ALL tell you that I am a safety Nazi! Many of them would probably also say that I sometimes ride extremely fast on public roads. But, even those people would also tell you that I have the best safety record of anyone they know. I have crashed on the street 1 time in the last 28 years or so. And that is because I work hard to KNOW what the limits are in whatever activity I'm engaged in. And then I am adamant about staying within the safe limits. At this point I have done enough research that I would say I have a basic understanding of how the dive tables work and all the different algorithms being used in these different Rec diving computers, and how the Buhlman algorithm with Gradient Factors works - in practical terms. Like motorcycling, I am approaching diving as something to learn as much as I can about it before I even put my first toe in the water. So, YOU may be perfectly comfortable limiting yourself to what your Mares tells you and I pass no judgment on that. But, I want to know what all the options. I want to know how they all work. And then I will make my own informed decision about what to use so that I am comfortable that what I am doing is safe - while also allowing myself the most time to enjoy the sport of diving. And make no mistake, making my own informed decision includes factoring in the input from experienced divers. I have been around the block enough times to know that experience often trumps spec sheets. Experience doesn't change the data - it just helps interpret the data in a different way than you might otherwise. That said, even the most experienced diver in the world could tell me "well, I use a Mares and it's fine for me, so there's no reason you could have for considering it to be too conservative" and I will still ask them "why? Can you show me the data on or explain why a more liberal computer wouldn't be better for me in the long run?"

I do understand that there's more to an NDL than just a number. There is a qualitative aspect to the decompression. And if I buy a computer that lets me stay down longer and I find that I don't feel that good when diving to those NDLs, then I will adopt a more conservative approach. But, I won't be FORCED to do that by my computer.

The bottom line: You cannot be considered "safe" (at least, not by me) if you don't KNOW what the limits are. If you are engaged in any activity that has hard limits (e.g. diving or riding a motorcycle or flying a plane or whatever), then the only way you can truly be safe is if you know what the limits really are. Otherwise, you will never know who close you are to them. I am researching the limits (of diving) and the limitations (of things like dive computers), in order to be as safe as I can. And I chose to share some of what I have learned. And I really do hope that if I've said something that is incorrect, someone will explain to me what is incorrect about it. For my safety and the safety of anyone who comes along later and reads what I posted.

So, do you have some data to share? Do you have more of an explanation than "I'm an old hand and it works fine for me and you're a newb, so you are automatically assumed to be stupid"? Or, let me make it even simpler for you. On a first dive to 60', an Oceanic computer will let you stay for 57 minutes. A Suunto will let you stay for "40 - 48" minutes. That is, according to another thread here on SB. What is the problem with telling someone that when they post that they are shopping for a computer and they list Oceanic and Suunto computers as ones they are considering?

---------- Post added September 22nd, 2014 at 02:29 PM ----------

Sure, some dive boats/ops supposedly "require" a computer... Guess what... I can't tell you how many times I flashed a Xen at an op that *required* a computer and they never blinked. A Xen is a BT only... not a PDC at all. The *required PDC" is a complete non-issue!!

Stuart, *please* consider waiting to dispense advice until you have some dives under your belt. There is a world of difference in what you can glean from research, and what you learn from experience. This is why almost everyone keeps telling you to get some experience [emoji4].

I hear you. I am trying. I THOUGHT that I had not given any advice in this thread. I didn't advise the OP to buy or avoid anything. I shared data about computers that I have learned from research. And I shared my own shopping plan, since I felt like I am in a similar situation to the OP. And from there, Lorenzoid jumped on me like I kicked his dog.

If sharing information is considered "giving advice" and it's unwelcome based on the number of dives the poster has, rather than based on the accuracy of the information, I am a bit disappointed, to say the least.

 

[doctormike]

Some of you are acting like I called your baby dumb and ugly! If you cannot refute the data posted, using other data (not anecdotes), apparently, you still feel a need to attack me... Lorenzoid jumped on me like I kicked his dog

Sorry, don't see any of that, even reviewing the thread. Your own posts seem pretty angry, actually, but I don't see much in the way of personal attacks going the other way (unless you consider pointing out that you have not actually tried scuba diving yet as an attack).

I suspect you and several others have developed an opinion of me that I am some kind of idiot and you expect that I'm going to be the kind of diver that you would never want to dive with.

No, you might be fine to dive with. Not sure I would want to be your instructor, though.

Experience doesn't change the data - it just helps interpret the data in a different way than you might otherwise.

What experience does is put the data into meaningful context. We see this a lot in the medical literature. Someone finds a paper that shows "x", and then it gets picked up by the press, and people who don't have the background or training to understand why "x" isn't clinically significant misunderstand the importance of the finding. Seriously, sometimes it's more than a single data point.

It seems that you are saying that one should pick the most "liberal" computer, and then decide on your own how close you want to get to NDLs, right? It's better if the computer tells you that you have 5 minutes left, and then you can decide when to go up, as opposed to the computer telling you have racked up 5 minutes of deco, and then you can decide whether or not it's safe to blow it off? Because it seems like that is what you are attempting to do, when you are choosing your computer based solely on that single table. Maybe I'm misunderstanding you.

Here, if you want another table to cut and past into these arguments, try this one. It shows the Suuntos to be less conservative. Maybe that will be helpful...

If sharing information is considered "giving advice" and it's unwelcome based on the number of dives the poster has, rather than based on the accuracy of the information, I am a bit disappointed, to say the least.

Sorry we disappointed you. We have done this before...

 

[lv2dive]

You are presenting information - sometimes irrelevant or misleading information - under the guise of "sharing data." 'Nuff said.

To the OP... Glad you have been able to sort through the sidetrack this thread has taken. There is a lot of good information here, from *experienced* divers. Have fun with your choice and your diving!

...
I hear you. I am trying. I THOUGHT that I had not given any advice in this thread. I didn't advise the OP to buy or avoid anything. I shared data about computers that I have learned from research. And I shared my own shopping plan, since I felt like I am in a similar situation to the OP. And from there, Lorenzoid jumped on me like I kicked his dog.

If sharing information is considered "giving advice" and it's unwelcome based on the number of dives the poster has, rather than based on the accuracy of the information, I am a bit disappointed, to say the least.

 

[Imla]

My personal experience... for any new person, not knowing what theyd do in the future, Id recommend a Suunto Vyper. It is reliable, reasonably cheap, well known, and has both light, nitrox and gauge mode.
It was the first computer I bought, and it is the only one I bring on _all_ my dives. (From avg time/depth single dive a day via tech dives gauge mode to multiple days multiple dives nitrox)
I have owned the following
Scubapro Bottomtimer (Impossible to break...)
Uwatec Tec2G (I think I ended up with 6 of them... they kept dying! Ie: bought one, and had it replaced 5 times...)
Suunto Vyper (My baby, just works and works...)
Shearwater Petrel (Hello mama!! Nice display, uses AA batteries, easily changeable, bluetooth transfer, full control of gradients and algorithms... Gotta love that baby!

With that said. Conservatism is in the eye of the beholder. Personally I have managed to (micro)bubble my shoulder in a 45 min dive, 3m (9feet!!)avg, and 10m max depth (it resolved in 45min on the surface, so no biggie). I have no idea why... I know my suunto was happy as a pixie on speed, so no stress there. However, NDLs are not just tables and algorithms. There are so many factors that need to be considered when judging if an algorithm is conservative or not. Among these factors are rest, physical condition, weather, temperature, workload, hydration, nutritional status, and so on.

What i DO know is that most people I have talked to that use the Vyper are happy with it. Most people I have talked to using the Petrel are happy with it.
The Tec2G i LOVED, with the BIG exception that it DIED and I couldn't trust it. (It just had all the functions I wanted...)

 

[Lorenzoid]

I already posted a link in this thread, to a sticky'ed thread in this forum, with a table showing the Oceanic and others giving an NDL of 57 minutes compared to the Suunto NDL for the same dive of "40 - 48" minutes. You really think I don't understand what that line in that table means? Is it not "a normal diving practice" to dive to 60' and stay there as long as 50 minutes?

If I recall that thread, the table related to one simplified dive profile for the sake of a rough attempt to rank computers by "conservativeness." See post #28 above by doctormike. Okay, assuming for the sake of argument that someone has a good reason for giving a lot of weight to "conservativeness" as a factor in choosing a dive computer--and some divers very well might have reasons--then that table might be useful as a rough estimation. Just keep in mind that whether one computer computes more no-deco time remaining than another depends to a large extent on the profile of that dive and of previous dives in a series, even over multiple days of diving in the case of some computers. What you're looking at are just a few data points, and some of us do not believe it's enough data to draw the black and white conclusions you seem to have been drawing. As a rough estimate, yes, maybe the table is useful.

As you have observed, there are indeed divers here on SB who have at times voiced consternation at their Suunto's seemingly low NDL computations. But Suunto is, and has long been, a very popular brand among the worldwide diving population in general, so it's clearly not causing problems for everyone, and I just don't think you should take the negative comments you've read here about Suunto's supposed conservativeness and repeat them as though they are going to be helpful to every new diver--a diver whom neither you nor I know much about.

It's nice that you and Lorenzoid have more conservative computers and you don't have an issue with the dive time you get. But, why do you feel like it's okay to use your personal dive habits and preferences as assumptions about what other divers are doing or going to do?

Huh? I interpreted YOUR first post as doing what you're accusing ME of!--giving the OP advice based on what you assume YOUR dives (or the OP's) will be like when you have never experienced what it's like to actually make your way through a real dive, where you have air limitations and buddies and other things that often trump your computed no-deco time. You don't know what the limiting factors are in the OP's dive times, and neither do I. In my comment, I tried to make it clear that we do not know what the OP's diving is like and we should not assume that he's going to run into a computer's supposed conservativeness impeding his diving. If I came off sounding like I was implying I know anything about the OP, I apologize. I used my own diving as an example, and said that each of us similarly knows what our dives are like: square profiles like in wreck diving? a deep stop on the ascent? a very gradual ascent like in some shore diving? ending a dive hanging out for 20 mins. on a coral reef at 20 feet? a spearfisherman doing a lot of sawtooth profiles? long surface intervals or short ones? how many dives per day? And what about our personal air consumption rate? And our buddy's. What size tanks are my buddy and I using? Diving and dive profiles can vary greatly--computed NDLs are not just about maximum depth and total time for one single dive. All of this together affects how long the dive is going to last. Others have chimed in saying that they, too, don't see the Suunto's supposed conservativeness as any major issue to fret over in choosing one's first computer, so I would guess their diving is much like mine. I think for many recreational divers, it's just not a big deal.

By the way, I can follow the reasoning behind your decision (and implicit recommendation, or so I thought) to buy a computer with a supposedly liberal algorithm and then on every dive manually (i.e., in your head) subtract 10 or 20 minutes to add conservatism to your own liking, but I don't think your logic is sound. You cannot know how much time to subtract in order to maintain yourself at some fixed level of safety. On some dives you may end up ascending sooner than you would have if you had bought the supposedly most conservative computer.

 

[BugHunterNY]

Here, if you want another table to cut and past into these arguments, try this one. It shows the Suuntos to be less conservative. Maybe that will be helpful...



Sorry we disappointed you. We have done this before...

Gasoline on the fire... Yay Scubaboard!


Sent from my iPad using Tapatalk

 

[doctormike]

computed NDLs are not just about maximum depth and total time for one single dive. All of this together affects how long the dive is going to last...You cannot know how much time to subtract in order to maintain yourself at some fixed level of safety. On some dives you may end up ascending sooner than you would have if you had bought the supposedly most conservative computer.

Stuart, if you can drop the defensive posture, read Lorenzoid's point again. It is true and very helpful. "Conservatism" isn't a fixed grade that each computer gets that allows for an ordered rank list.

You can learn something from another diver even if it doesn't jibe with the conclusion that you reached based on a table you found in one thread in a public forum. Ironically, the sentence that follows the chart in the thread that you keep citing is "However, be wary of putting too much stock in this point"...!

I'm always happy to learn new things. I am not the most experienced person in this thread by a long shot, but after over 700 dives and technical training, I'm still open to the possibility that some of what I "know" for sure is wrong. So maybe try to hear what people are telling you instead of just being a right fighter.

---------- Post added September 22nd, 2014 at 04:38 PM ----------

Gasoline on the fire... Yay Scubaboard!

Meh. The fire is more interesting than the OP. Besides, I always answer that question these days with "get a Petrel".

 

[cascas]

I'm done with it. Stuart, do whatever you want.

As padi instructor, full cave and full trimix certified diver, apparently I'm not in a position to tell you anything.
I'll just shut up.

Good luck.

 

[Tbar]

I already posted a link in this thread, to a sticky'ed thread in this forum..

Sorry I don't read all of you posts

It's nice that you and Lorenzoid have more conservative computers and you don't have an issue with the dive time you get. But, why do you feel like it's okay to use your personal dive habits and preferences as assumptions about what other divers are doing or going to do? You tell us that you have no issue with your Mares and Lorenzoid has no issue with his Suunto, implying that one of those should be good enough for anyone. Well, instead of implying that no one should have an issue with limiting their dives to as short as what you do, what is wrong with giving the OP the info about how the different computers work and let the OP decide what will be best for him or her?

Again you fall back to the misinformation of dive times, and a very small information base you have seen.

I suspect you and several others have developed an opinion of me that I am some kind of idiot

Sorry to disappoint you, it is not about you or if I have an opinion, its about true information and real world experience.

The bottom line: You cannot be considered "safe" (at least, not by me) if you don't KNOW what the limits are. .... I am researching the limits (of diving) and the limitations (of things like dive computers), in order to be as safe as I can

That is just a dangerous paragraph, for a NDL every person will have different limits in different conditions and situations! There is no magic 'I am inside my NDL', the whole time we dive we have a decompression obligations, at times this can be done on the surface and at other times initiated under some pressure (a deco stop). Part of our assent is decompression and computers take this into account.

So, do you have some data to share?

Two dives over the weekend, first to 30m second to 27m with about 60 minute SIT. We had 8 divers with a range of equipment including various computers Zoop, Puck, Oceanic, and others. Two divers were on Nitrox 32%. On the first the divers on air had the same planned time, those on Nitrox additional time. On the second dive those on air had planned times with two minutes, given that their fist dive profiles will have been different this is a very close plan. I was one of the boat watch persons so was capturing the details.

I dive with similar groups regularly, on similar profiled dives, and complete the dive logs. I do not see any appreciable difference in dive plans based on computers, it is impacted more by diving different depths, times and SIT.

 

[cascas]

The bottom line: You cannot be considered "safe" (at least, not by me) if you don't KNOW what the limits are. If you are engaged in any activity that has hard limits (e.g. diving or riding a motorcycle or flying a plane or whatever), then the only way you can truly be safe is if you know what the limits really are. Otherwise, you will never know who close you are to them. I am researching the limits (of diving) and the limitations (of things like dive computers), in order to be as safe as I can. And I chose to share some of what I have learned. And I really do hope that if I've said something that is incorrect, someone will explain to me what is incorrect about it. For my safety and the safety of anyone who comes along later and reads what I posted.

Tables are based on models not on exact science. No one knows what the limits are and even if those limits were known, they would be different for you or me. They could even be different tomorrow compared to today. Don't fixate on the conservatism of computers, most have settings that allow you to adjust them to more conservative or less conservative anyway.

Besides, a more conservative computer may give you a shorter ndl than another while it may allow you to stay down longer on a repetitive dive.

Then there is the issue that while a suunto may not let you stay down as long as another brand at say 60 ft, as you are ascending your ndl will be recalculated according to the new depth. In the end you can have a dive that will get you to your gas supply limit before you ever see the ndl approaching.
There is no need ascending to the surface when your ndl at depth is met. That is why I said to do the course first, you would then have known that using a computer gives you a sliding ndl.

Have fun doing the course, and stop fussing about conservatism, it's no big deal and it will very likely never cause you any grief.