What computer do you dive with?

Wrist, console...for recreational or technical diving. Questions and information.

Re: What computer do you dive with?

Postby guru » Thu Apr 09, 2009 7:53 pm

I've got my Uncle's US Divers 4. Big screen which i find easy to read :)
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Re: What computer do you dive with?

Postby ChrisB » Sun Apr 19, 2009 12:13 am

As a self confessed newbie with only 35 dives, i was nearly talked out of a Mares Nemo XL and into a Puck... by my LDS (guessing this means Local Dive Store)
i purchased the XL

I have a question to ask also - while on a recent trip with Northland Dive, after a swim thru the Canterbury i went into deco and the computer showed 3m for 5min deco stop. As i ascended past 15m it suddenly changed to deepstop but doesn't show how long to stay there. Is this common for these computers, and am i expected to return to 3m then drop down to do safety stop? Am i interpreting this correctly?
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Re: What computer do you dive with?

Postby DiveDiva » Sun Apr 19, 2009 9:06 am

Hi ChrisB,

Welcome to the forum :D Do you mean that your computer switched to a deepstop mode or did it go into a decompression setting? It's usual for a dive computer to alter stops during an ascent, depending on your profile but it should tell you time remaining at each stop, shouldn't it??? I did used to have a NEMO but never took it into deco. Can anyone else help Chris out here???
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Re: What computer do you dive with?

Postby ChrisB » Sun Apr 19, 2009 11:44 pm

Thanks Divediva
Went into deco mode but as its only the first time i've been greedy on BT maybe i didn't read it correctly- it started to beep the told me to deco with depth 3m for 1 min to start with. As i ascended, as mentioned it changed to "deepstop" as i passed 15m but don't recall it showing me a time to stay as such. But i think i ended up staying for aprox 2min before continuing up to 3m.
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Re: What computer do you dive with?

Postby binklebonk » Mon Apr 20, 2009 1:21 am

EDIT- Should've read the bloody question-EDIT...... :roll:

MESSAGE FROM DD: Would you like this post deleted BB?

Nah mistakes keep us humble...
Last edited by binklebonk on Tue Apr 21, 2009 7:13 pm, edited 2 times in total.
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Re: What computer do you dive with?

Postby Andy » Mon Apr 20, 2009 10:09 am

ChrisB wrote:I have a question to ask also - while on a recent trip with Northland Dive, after a swim thru the Canterbury i went into deco and the computer showed 3m for 5min deco stop. As i ascended past 15m it suddenly changed to deepstop but doesn't show how long to stay there. Is this common for these computers, and am i expected to return to 3m then drop down to do safety stop? Am i interpreting this correctly?



That sounds a bit odd, Chris. Normally it should show you the ceiling as the deepest stop - most Mares computers essentially have a "bend and mend" model, which takes you very quickly to the shallowest stop. Maybe the newer ones have introduced a deep stop into the model, or as BB has pointed out there was something on your ascent that made it change it's minds. Knowing a bit about how the RGBM model has been implemented, I would expect that it may also be something to do with going up and down a lot in the dive profile? You are DEFINITELY NOT expected to go to 3m then drop back down to 15m.

One of the more common (and utterly unvalidated approaches from a scientific point of view) to deep stops is the "Pyle stop". A Pyle stop is generally a 2 minute stop at roughly half your maximum depth (it's a bit more complex than that - but this makes it easier to describe). So if you do a 30m, you'd stop at 15m for 2 minutes. If you had a 3m ceiling at that point, you'd then do a second stop at half the depth between the current stop and the ceiling (15 - 3) / 2 = 6; then 15 - 6 = 9m. If you still had a ceiling, you'd repeat the process.

One of the problems with many recreational computers is that they don't credit you for those deep stops - Nat was using Jamie's Nemo XL on the Warrior and we found it has this problem. Doing "a little bit of deco in recreational depths", I tend to introduce Pyle stops in all of my dives (disclaimer: I don't recommend this as the best option and suggest that people make their own informed choice after reading on the subject and getting training in decompression diving), and when I was doing my deeper stops the Nemo was still clocking up deco time. Even though we were off gassing in some tissues, it was still worrying about ongassing in the others.

We did find out later that the Nemo was set to 1500m altitude, so it will not penalise as much if it was set to sea level... but it still wasn't totally happy.

The best option for anyone intending to do some deco, no matter how little, is to get some good training and understand what the computer is telling you to do and why. Blindly following a computer and hoping it will be alright is recipe for trouble, IMHO.
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Re: What computer do you dive with?

Postby tara » Mon Apr 20, 2009 11:35 am

ChrisB wrote: ... while on a recent trip with Northland Dive, after a swim thru the Canterbury i went into deco and the computer showed 3m for 5min deco stop. As i ascended past 15m it suddenly changed to deepstop but doesn't show how long to stay there. Is this common for these computers, and am i expected to return to 3m then drop down to do safety stop? Am i interpreting this correctly?


the DEEPSTOP message is telling you that you should be staying at that depth for one minute. nemo can give you more than one of these per dive. it will alarm these deepstops when you are close to the decompression limits. it will also show you decompression stops if you are required to make them and will alarm and change the arrows if you are too deep/not deep enough for these stops.

really, you should read your manual before you go diving with new equipment especially if you are doing decompression dives.
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Re: What computer do you dive with?

Postby ChrisB » Mon Apr 20, 2009 9:21 pm

[quote="AndyThe best option for anyone intending to do some deco, no matter how little, is to get some good training and understand what the computer is telling you to do and why. Blindly following a computer and hoping it will be alright is recipe for trouble, IMHO.[/quote]

Thanks for your input Andy. Will discuss it further with Jamie at next weekend. If your going to be there might talk it over with you also.

Tara - i had read the manual and had it with me but it doesn't really explain the deco stops very well, hence my questions.
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Re: What computer do you dive with?

Postby Andy » Mon Apr 20, 2009 10:43 pm

I'm going to be missing the weekend, Chris.... I'm flying out to Vegas for a week which scews up the next two weekends. I'll be in the Abbey on Thursday, though.

It doesn't make sense to me for a computer to tell you that the ceiling is 3m, then telling you after you get there that you have to do a deep stop. Unless Mares have picked up their game, I'm sure the manual is not much use - my old M1 manual was basically a set of screenshots with no info. There might be an option to turn the deep stops off??

Just done a bit of digging - the XL doesn't display the need for a deep stop until you get near the deep stop depth. WTF?! How unintuitive is that? You can, however, do a look ahead at any time to see whether you need to do a deep stop of 1min by pressing the ESC button. It's not suprising you were a bit confused, Chris.

I've got some articles on deep stops and simple deco theory - I won't do what I did to Mike (200 pages of research on whether you can dive deeper on your second dive!), but will post them up tomorrow when I get back to work.
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Re: What computer do you dive with?

Postby ChrisB » Mon Apr 20, 2009 10:59 pm

Thanks Andy will see you Thursday

Sorry everyone else for hijacking the thread !! :oops:
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Re: What computer do you dive with?

Postby tara » Tue Apr 21, 2009 1:16 am

i find the mares rather easy to use.
you cant turn the deep stops off and they only come on when you are within 1 min of decompression.

now i dont mean to be too harsh but what the hell are you doing that close to your limits with a computer that you dont know how to use.
unless you have planned your dive and noted your stops on a slate, you should know exactly what your computer is telling you - otherwise use one that you do understand (or even agree with).

the mares manual is more than screenshots now, however i take it that some people have an aversion to these computers.
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Re: What computer do you dive with?

Postby Andy » Tue Apr 21, 2009 11:01 am

tara wrote:now i dont mean to be too harsh but what the hell are you doing that close to your limits with a computer that you dont know how to use.
unless you have planned your dive and noted your stops on a slate, you should know exactly what your computer is telling you - otherwise use one that you do understand (or even agree with).



That's very harsh, Tara.

Let's be blunt, all of us have done deco without being properly trained or prepared - in many cases that's a driver to seek out additional training. I know plenty of experienced divers who have fouled up, gone in to deco and had a close call. I even know instructors who have not calculated their gas requirements or the mandatory stops and had some very near misses, even when teaching.

Let's use the benefit of our experience to help Chris along the way, rather than tell him what not to do.
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Re: What computer do you dive with?

Postby tara » Tue Apr 21, 2009 11:10 am

okay so it was harsh. true though.
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Re: What computer do you dive with?

Postby JohnSymons » Tue Apr 21, 2009 3:56 pm

Andy wrote:Let's be blunt, all of us have done deco without being properly trained or prepared - in many cases that's a driver to seek out additional training. I know plenty of experienced divers who have fouled up, gone in to deco and had a close call. I even know instructors who have not calculated their gas requirements or the mandatory stops and had some very near misses, even when teaching.


Generalizations kill as some of us choose to undertake being properly trained and prepared before undertaking a specific new type of diving (Deep, night, deco, penetration, etc). Eventually it all comes down to this adage, Plan the dive and dive the plan, whether it is "deco" diving, night diving or any other type of planning, entering the water with no max depth or time plan or reserve supply is simply just asking for trouble, especially if you are diving with someone that you are not necessarily familiar with as this can often times resulting in one person or the other pushing their limits and exceeding their experience level. Just because you know instructors who haven't done it doesn't mean that it is behavior that should be condoned or even supported as it quite literally is what is going to get divers injured or killed.



As far as the computer I dive with, I used to use Scubapros Smartcom, but recently upgraded to a Gallileo Sol when I was able to pick it up directly from Scuba Pro at keyman. Functionality of the Sol is amazing and was nice to get out of a console finally and into a wristmount system. Love both and have been enjoying the transition in data output available during dives and the ability to see more or less at will depending on what i am doing or what i want displayed.
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Re: What computer do you dive with?

Postby ChrisB » Tue Apr 21, 2009 8:16 pm

tara wrote:i find the mares rather easy to use.
you cant turn the deep stops off and they only come on when you are within 1 min of decompression.

now i dont mean to be too harsh but what the hell are you doing that close to your limits with a computer that you dont know how to use.
unless you have planned your dive and noted your stops on a slate, you should know exactly what your computer is telling you - otherwise use one that you do understand (or even agree with).

the mares manual is more than screenshots now, however i take it that some people have an aversion to these computers.


true enough tara - i could have been paying more attention, i was enjoying the dive too much, and in a group of 4 ppl. As soon as i noticed i was right on deco limit, i signalled my buddy and we headed up to better depths. Sometimes the best way to learn is to do and see, and now i understand my computer better i am more prepared. This was only the second trip i have used it, and have never come close until now.
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