Surface Interval start...

[Clownfish]

1 It makes no difference to deco calculations and if you think you must stay out exactly 60 minutes, it is in fact safer as you will be out 64 minutes
2 It will not as I am not that anal to want to have a SI of exactly 60 minutes and I can add 4 minutes to my SI
3 No need, as I said, I can add 4 minutes to whatever the shown SI is and it makes it safer if I foreget
4 I do not know why someone would need to know their SI to this exact level


The fact is, if it was the other way, reporting a SI that was 4 minutes longer than it really was, I would support you. This is inconsequential and does not need to be resolved. Every computer I have ever shown has not shown correct SI when you later compare all the times.

Get over it, it does not matter.

[cheeseandjamsandwich]

Clownfish Wrote:
-------------------------------------------------------
> 1 It makes no difference to deco calculations
> and if you think you must stay out exactly 60
> minutes, it is in fact safer as you will be out 64
> minutes
We know it makes no difference, we've stated that clearly above. Please read the thread.
Conservatism is great, but this thread and the SI value isn't about conservatism. It's about the dive computer telling the diver how long he's been on the surface.

Clownfish Wrote:
-------------------------------------------------------
> 2 It will not as I am not that anal to want to
> have a SI of exactly 60 minutes and I can add 4
> minutes to my SI
If it doesn't matter to you, then it could be changed and you won't care. therefore we don't need your negative input.
Computers are good a maths, let it do it.

Clownfish Wrote:
-------------------------------------------------------
> 3 No need, as I said, I can add 4 minutes to
> whatever the shown SI is and it makes it safer if
> I foreget
'No need' isn't an explanation of your position. Answer the question.

Clownfish Wrote:
-------------------------------------------------------
> 4 I do not know why someone would need to know
> their SI to this exact level
You do not know why, but that does not mean the nobody does.
But it's nice to know that you agree that the current SI is wrong.

Clownfish Wrote:
-------------------------------------------------------
> This is inconsequential and does not need to be resolved.
In your view, but you can't see other peoples views.

Clownfish Wrote:
-------------------------------------------------------
> Get over it, it does not matter.
If so, then you don't need to read this thread, you don't care and won't mind if it is corrected.


Why are you being so negative and selfish about something that won't affect you and you don't care about?

[gorcio]

Stop it man, no chance (whether I agree with you or not (=not, in this case) ). It was the same with implementing Safety Stop which I advocated against, and when it was implemented, it was implemented with weird values allowed for it. I still can't understand what was the purpose of implementing something that vast majority of OSTC users won't use at all, and doing it rather in a careless manner. Jest waste of bytes

[cheeseandjamsandwich]

gorcio Wrote:
-------------------------------------------------------
> Stop it man, no chance (whether I agree with you
> or not (=not, in this case) ). It was the same
> with implementing Safety Stop which I advocated
> against, and when it was implemented, it was
> implemented with weird values allowed for it. I
> still can't understand what was the purpose of
> implementing something that vast majority of OSTC
> users won't use at all, and doing it rather in a
> careless manner. Jest waste of bytes

Sigh.
Please RTFT!!!
I just spotted a bug and asked for it to be fixed.
The 'Surface Interval' reported is 240 seconds shorter than it should be. It's very, very simple. No extra functionality is being added, no Custom Functions are being created. If it is corrected, you probably won't even notice.

Why are you being so negative to someone reporting a bug??? What are you after?

Posts like yours and others are not doing this community any favors. The 'Safety Stop fiasco' (i reread it all) was an utter embarrassment, so many negative posts and what can only be described as Deco-Snobbery. Like Matthias said, they probably lost a few customers due to those arguments and unfortunately we might do here too. This thread is almost certainly going to put off anyone even thinking of submitting a bug report for the fear of the pack descending on them with with hateful negativity and insistence that they must use their brain for every little thing.
If you think i am wrong about the bug, then justify yourself with a thought-through explanation, that's what I've had to do (and didn't expect i'd have to, as it's sooooo bloody easy to see and understand). "I'm right because I AM" is not an explanation or justification.
How is your world going to be affected by this fix??? It probably isn't. If something doesn't matter to you, then we probably don't need your input. And definitely not your negativity.


This is a simple bug fix request.

[Laurie_the_Knot]

I remember the "Safety Stop" correspondence and the heated discussion contained therein. Initially I was against it's implementation as at the time we only had 64 CFs to play with. Subsequently Matthias has added an additional 32 CFs and the safety stop functionality has been added using 5 CFs, one more than necessary if CF70 were used to enable/disable the safety stop feature in my opinion. I now have the feature enabled and use it on every no-deco dive I do.

As we appear to have over 20 spare CF slots why can't this 'feature' be enabled/disabled by making use of one of these spare CFs. That way we can keep both camps happy.

[scubatinoo]

Laurie_the_Knot Wrote:
-------------------------------------------------------
> ...why
> can't this 'feature' be enabled/disabled by making
> use of one of these spare CFs. That way we can
> keep both camps happy.

Because it's not a feature, and it's not a bug - it's just Rich's opinion about how he understands the SI or ST...

I'm wondering what he is going to ask, if he regognizes that his OSTC will switch from surface mode to dive mode with some delay too... Ooops!

[cheeseandjamsandwich]

scubatinoo Wrote:
-------------------------------------------------------
> Laurie_the_Knot Wrote:
> --------------------------------------------------
> -----
> > ...why
> > can't this 'feature' be enabled/disabled by
> making
> > use of one of these spare CFs. That way we can
> > keep both camps happy.
>
> Because it's not a feature, and it's not a bug -
> it's just Rich's opinion about how he understands
> the SI or ST...
>
> I'm wondering what he is going to ask, if he
> regognizes that his OSTC will switch from surface
> mode to dive mode with some delay too... Ooops!

The Surface Interval has absolutely nothing to do with a dive computer, which one the diver is wearing, whether he is wearing one at all. If you have been on the surface for 34 minutes, then that is your surface interval. This is clearly defined by all the diving text books, etc.
Do you follow this? scubatinoo? Do you challenge this definition? If yes, clearly state your reasoning.


The OSTC is timing the SI after the dive mode time-out, which is 240 seconds after surfacing, therefore it isn't reporting it correctly, which is unexpected, therefore it is a bug (as per the definition of a software bug)
Do you follow this scubatinoo?

The dive mode time-out is a very important feature, it serves a purpose and does it very well. It does not need to, and must not, be changed. This bug fix request has nothing to do with the dive-mode time out.
Do you agree with this scubatinoo? I'm wondering if you've misunderstood me for wanting to change this?

scubatinoo, do you remember the Safety Stop threads? You were banging your head against the wall fighting the irrational deco-snobs. You were suggesting very sensible things and explaining them well. It's like you have now moved over to 'The Dark Side'

Laurie, no CF is needed for this, it's probably a simple change in the code to get the safety stop timer to start at surfacing instead of divemode timeout.

The only change to the OSTC will be the surface interval time displayed, no other functionality will be changed at all.

[scubatinoo]

cheeseandjamsandwich Wrote:
-------------------------------------------------------
> Do you challenge
> this definition? If yes, clearly state your
> reasoning.

Yes i do. Because if you carefully read your 2 quotes from the navy book and from wikipedia about when SI starts, you'll regognize that even this two definitions are not the same! And then, dear Rich: Not every diver is breathing air when reaching the surface... Different divers, different needs. And that's where OSTC scores!

It's definitely my EOD.

[cheeseandjamsandwich]

scubatinoo Wrote:
-------------------------------------------------------
> cheeseandjamsandwich Wrote:
> --------------------------------------------------
> -----
> > Do you challenge
> > this definition? If yes, clearly state your
> > reasoning.
>
> Yes i do. Because if you carefully read your 2
> quotes from the navy book and from wikipedia about
> when SI starts, you'll regognize that even this
> two definitions are not the same!
Therefore the Surface Interval must be wrong by 4 minutes?
So to recap, save you scrolling again:
From the U.S Navy Diving Manual rev. 6
[pre]
Surface Interval. In the context of repetitive diving, the surface interval is the
time a diver spends on the surface between dives. It begins as soon as the diver
surfaces and ends as soon as he starts his next descent.
[/pre]

From Wikipedia (100% true always!)
[pre]
The surface interval (SI) or surface interval time (SIT) is the time spent by a
diver at surface pressure after a dive during which inert gas which was still
present at the end of the dive is further eliminated from the tissues.
[/pre]
So in the context of this thread, how are they different?
"It begins as soon as the diver surfaces" at surface pressure...
"time spent by a diver at surface pressure" which is at the surface.

> And then, dear Rich: Not every diver is breathing air when
> reaching the surface...
Therefore the Surface Interval must be wrong by 4 minutes?
But he is at surface pressure breathing it.

> Different divers, different needs. And that's where OSTC scores!
Therefore the Surface Interval must be wrong by 4 minutes?

> It's definitely my EOD.
"I'm right, because I AM"?

Why must the surface interval be wrong by 4 minutes??? Or by whatever time a diver chooses for the totally unconnected Dive Mode Time-out... ????

Where's this 240 seconds written in the decompression theory papers and books? cite them.

You are making zero sense. Do you understand logic? Are you just trolling?

[Stephane]

I am very fine with the way SI is implemented. I would be very fine if it was implemented the way you want.
You think this is a bug but others don't (and most important of all, HW don't see this as a major bug).
So if you want it to be changed, either provide some stronger arguments or find someone that can correct the software for you.
I once asked if it would be a good idea to implement a "turn off" function, Mathias replied that he did not think so and that he wouldn't do it, I'm not a programmer, I'm living without my (not so) great idea.

[cheeseandjamsandwich]

Stephane Wrote:
-------------------------------------------------------
> I am very fine with the way SI is implemented. I
> would be very fine if it was implemented the way
> you want.
For a lot of divers, there's no reason at all to worry about the surface interval being 4 minutes out.
And i genuinely thought that everyone would be like you, and would be fine about it being fixed. Why would they???
I'd assume that if SI time was wrong, then a few people, like me, would care, but if it was reading correct NO ONE would object.

> You think this is a bug but others don't (and most
> important of all, HW don't see this as a major
> bug).
The issue here is that it is quite simple to see that it is a genuine bug. I wasn't expecting any conflict or arguments over this fact. It reads wrong by 4 minutes. That is all.
HW didn't indicate whether they thought it was a bug or not, just that they didn't think they'd change it.
I totally agree that this is only a minor bug. But it is needlessly wrong, and something that i'd expected to be eliminated very early on in development and no one would have ever noticed. But bugs remain and pop up, fact of life.
But i really thought that this would have just been acknowledged and fixed, with no one throwing their dolls out of the pram about it.

> So if you want it to be changed, either provide
> some stronger arguments or find someone that can
> correct the software for you.
Why should i keep a simple bug fix to myself?
I don't know if you noticed, but i've calmly gone to great lengths to justify this bug. Establishing the cause. Pulling out all the definitions for the SI and Software Bugs. Listing the numerous little reasons why it might be nice to know how long a diver has been on the surface. And repeated them a few times.
So many of the posters have totally ignored these justifications, repeating stuff that's already being addressed or just coming out with weird stuff that doesn't use any form of logic or reasoning.

> I once asked if it would be a good idea to
> implement a "turn off" function, Mathias replied
> that he did not think so and that he wouldn't do
> it, I'm not a programmer, I'm living without my
> (not so) great idea.
This is just a bug, not a feature.
Bugs are usually always fixed when found.
But new features must be examined before implementation to see if they are necessary, useful, a bitch to code, use up valuable resources, cause safety concerns, etc, etc, etc...
Feature requests are also subjective. Some people like them, some people need them, some people won't use them, some people hate them.

Just like the whole Safety Stop Fiasco. There were some genuine arguments for not implementing it, like the lack of Custom Functions available (that was fixed with the 3rd CF page)... feature creep, which is something to keep an eye one for sure, too much stuff littering the display, etc... but they were week (subjectively speaking Sadly the other reasons for not wanting it appeared to be based on 'deco-snobbery', people not wanting their tech diving computer to have any recreational dive computer features! This was bizarre and made no logical sense as the feature could be turned off. The reasoning for implementing it were strong and described quite clearly, listing genuine realities of diving, whereby tech divers will probably be doing many recreational dives too, and that this feature is a nice to have, a dive computer is very good at simple little tasks like this. Plus safety stops genuinely save a few lives.
The initial implementation of the feature wasn't perfect, and more arguing continued rather than just letting the modifications be requested and justified.
The final implementation of the safety stop feature is now probably the most flexible of any DC, it works perfectly and has all the settings we need... Including the all important on/off switch

The Surface interval bug is logical, not subjective. That's why i am sticking up for myself and justifying it with the reasons.
Someone has to rewrite the definition of a Surface Interval for it not to be a bug... And that would be an interesting thread to read! LOL!

HW fixes bugs every day... How the hell did this one turn into such a mess?!

But thank you Stephane for stating that you'd be ok with fixing it.
I guess many people are too scared to post here now.


So for the millionth time, this is a simple little bug that is needlessly wrong and easy to fix.

[heinrichsweikamp]

Is swimming/diving between 0 and 1m already part of the surface time or is is just the final part of the dive?

I haven't read the whole thread now (Just returned from the "boot" dive show).

The surface interval starts when the unit is in surfacemode (The OSTC starts computing your desaturation time and nofly time when it's in surface mode, too) and we won't change that.

Regards,
Matthias

[cheeseandjamsandwich]

heinrichsweikamp Wrote:
-------------------------------------------------------
> Is swimming/diving between 0 and 1m already part
> of the surface time or is is just the final part
> of the dive?

I'd expect that the definition of the SI assumes that you are ascending directly to the surface, which 99% of divers probably do.
If you are swimming/diving between 0 and 1m, then the OSTC is still going to time-out of dive mode isn't it?
I'd say that this would be a special case and not relevant.

> I haven't read the whole thread now (Just returned
> from the "boot" dive show).

No probs
Jealous i couldn't go!

> The surface interval starts when the unit is in
> surfacemode (The OSTC starts computing your
> desaturation time and nofly time when it's in
> surface mode, too) and we won't change that.

The readings of the desat and nofly times are fine. They're theoretical times generated by the deco model.

But a Surface Interval is clearly defined and independent of any dive computer/mode/deco model/etc. It's just a function of the diver being at the surface.
So i'm just suggesting that the OSTC could report the time since the diver was at the surface, as per its definition.

[Clownfish]

Based on Matthias's last post, the off-gassing calculations only start when the OSTC goes into SI mode. Therefore, the way it works is exactly correct, the SI as far as the computer is concerned for its calculations only starts after the time-out period.

[heinrichsweikamp]

cheeseandjamsandwich Wrote:
> But a Surface Interval is clearly defined and
> independent of any dive computer/mode/deco
> model/etc. It's just a function of the diver
> being at the surface.

I think there are several examples where the border between surface swimming and diving is not exact. I would say your request to have the surface interval timer starting earlier will be as exact as the current solution. So why change it?

regards,
Matthias

[cheeseandjamsandwich]

Clownfish Wrote:
-------------------------------------------------------
> Based on Matthias's last post, the off-gassing
> calculations only start when the OSTC goes into SI
> mode. Therefore, the way it works is exactly
> correct, the SI as far as the computer is
> concerned for its calculations only starts after
> the time-out period.
I was wondering that too, but i think one of the other explained that the calculations are running all the time and just based on the pressure???
He said the desat & no-fly (And SI) times are calculated when dive mode times out, but they're theoretical times from the deco model, which assumes some things and can't know so many other things (diver temperature, hydration, fitness, susceptibility, tiredness, etc, etc.) So these have conservatism built in i assume and could be out by hours from your true (unknowable) desat time. A theoretical time of many hours being wrong by 4 minutes can be Ignored.

The SI is an exact time. If you have a dude sitting on the dive boat with a stopwatch, waiting for your head to pop up, he could tell you to the second (That is overkill!) what your SI is any time later. And he would be correct. It's just the time from when you surfaced.

Please understand (as i've explained above more than once) The Surface Interval has absolutely nothing to do with the dive computer. If you don't wear one, your SI is exactly the same. If you dive with a rebreather, your SI is exactly the same. It's just the time from when you surfaced.

The OSTC knows exactly when you surfaced (as far as it's concerned, when you pass certain depth/pressure thresholds, 1m?), this is when it starts timing the Dive Mode Time-Out... 240 seconds later it triggers the all the stuff listed by Matthias above and switches to surface mode. So the OSTC could just start timing the SI at the same time as the dive mode time-out. And when it becomes visible later, after switching to surface mode, the custom display will say your surface interval is already 4 minutes. And this would be absolutely correct.

[cheeseandjamsandwich]

heinrichsweikamp Wrote:
-------------------------------------------------------
> cheeseandjamsandwich Wrote:
> > But a Surface Interval is clearly defined and
> > independent of any dive computer/mode/deco
> > model/etc. It's just a function of the diver
> > being at the surface.
>
> I think there are several examples where the
> border between surface swimming and diving is not
> exact. I would say your request to have the
> surface interval timer starting earlier will be as
> exact as the current solution. So why change it?
>
> regards,
> Matthias

I agree there are examples, sure. But they're rare. it's normal for almost all divers to slowly ascend from their last deco/safety stop directly to the surface.
The OSTC, like any other dive computer has to use the assumption that the diver has surface when particular thresholds are met. Like the 1m depth setting we use??? This is just a reality.
This i think is when the dive time is recorded in the logbook? Correct? ..I read the source code and think this is when it's triggered??? My code skills are limited

At the moment, the Surface Interval is wrong by 4 minutes.
And implementing the fix will mean the surface Interval is wrong by 0 minutes.

Why fix any bug?
OK it's only a small one, but there's no reason for it to be wrong.

[heinrichsweikamp]

cheeseandjamsandwich Wrote:
> At the moment, the Surface Interval is wrong by 4
> minutes.
> And implementing the fix will mean the surface
> Interval is wrong by 0 minutes.
>
> Why fix any bug?

Ok, last try: We don't consider this as a bug and we won't change it in the release branch. Surface Interval timer is started when the surface mode is entered. Everything before is considered as part of the dive and logged into the profile memory.

Regards,
Matthias

[cheeseandjamsandwich]

How about we think about this the other way around.


Imagine that the OSTC had been programmed to start the Surface Interval timer when it had assumed you'd surfaced, when the depth threshold was reached, when it then started timing the dive mode time-out... And how most, if not all other DCs work... It had done that from day one, everyone was used to that.

Now imagine that i pop up, posting in the forums, that i wanted the surface interval to start 4 minutes later, at the time when the screen changed from dive mode to surface mode, and i had some reasoning for this (i can't actually think of any).

This would cause a much larger deluge of posts objecting, telling me to use my head, telling me to just forget about it, etc, etc. And they would be 100% correct and justified in what they'd say.

[cheeseandjamsandwich]

heinrichsweikamp Wrote:
-------------------------------------------------------
> cheeseandjamsandwich Wrote:
> > At the moment, the Surface Interval is wrong by
> 4
> > minutes.
> > And implementing the fix will mean the surface
> > Interval is wrong by 0 minutes.
> >
> > Why fix any bug?
>
> Ok, last try: We don't consider this as a bug and
> we won't change it in the release branch. Surface
> Interval timer is started when the surface mode is
> entered. Everything before is considered as part
> of the dive and logged into the profile memory.
>
> Regards,
> Matthias

A question:
So is the dive time decided at the end of the dive mode time out? So if i did a dive and promptly surfaced 20 minutes later, the logged dive time would be 24 minutes?

I've never noticed a difference in dive times between my dive computers (need to check this tomorrow).
But i do notice that the surface interval is 4 minutes out every time...
Hence my initial post.

[heinrichsweikamp]

cheeseandjamsandwich Wrote:
> So is the dive time decided at the end of the dive
> mode time out? So if i did a dive and promptly
> surfaced 20 minutes later, the logged dive time
> would be 24 minutes?

No.

> But i do notice that the surface interval is 4
> minutes out every time...
> Hence my initial post.

I think most of us fully understood your request. See the following dive:

[img]file.php?2,file=491,filename=image.PNG[/img]

Even that I was at the surface again at about 34:45, (for me) the dive ended at ~40min. And after that the surface interval starts.

Regards,
Matthias

[cheeseandjamsandwich]

heinrichsweikamp Wrote:
-------------------------------------------------------
> Even that I was at the surface again at about
> 34:45, (for me) the dive ended at ~40min. And
> after that the surface interval starts.
I don't totally follow what you're saying here.
Diving Log correctly gives the dive times on my dives, with the 4 minute surface 'tail' of the profile showing like yours does above. So diving log said your 'dive time' was 34:45?

When YOU SURFACED, that's when YOUR SURFACE interval starts. It's defined as that.
It has nothing to do with when the OSTC.

It's about you being on the surface.

This is pure logic.

Why must the time the diver has been on the surface be reported as 4 minutes less than the time the diver has been on the surface?

[cheeseandjamsandwich]

heinrichsweikamp Wrote:
-------------------------------------------------------
> I think most of us fully understood your request.

Shame only 2-3 of them posted in this thread though

[boefst]

I totally agree with you Rich.

I remember the Swedish dive tables from the 80:s used ten minutes instead of the four minutes the OSTC now uses.

If I surfaced to speak to my buddy, I could do that for up to ten minutes, without the need to calculate a new dive. Just as the OSTC does, if I descend again within the four minutes. It is still the same dive.
If we in the 80:s decided to descend again, the few minutes on the surface was included in the total dive time and had to be considered when planning the next dive.

However, if we instead of continuing the dive decided to swim ashore for lunch, the SI was calculated from surfacing. Not ten minutes after. The time from my appearance at the surface was used to calculate were to enter the tables when planning the dive after lunch.

Pretty obvious, I think.

Why the OSTC has another approach to this I don´t understand.



/anders