A Dive Computer for the Tech Newbie - Page 3

**neilh** · June 17th, 2009, 09:32 AM

Quote: (Originally Posted by Jack911)

You don't carry computers? Seriously?

Yup, seriously.
Well, ish

Technically I (and many others) do wear a dive computer - but as someone posted earlier it's set in gauge mode so during the dive all it tells me is the depth, time and temperature. After the dive I can access the logs on it or download the profiles to my PC - but it's not being used to compute anything during the dive.

Quote: (Originally Posted by Jack911)

I'm intrigued. Can someone please explain how a bottom timer is safer than a computer?

Is it any less safe?
A computer is looking at the gas you've told it you're using, your depth and your time and applying whatever model it's designed with to those parameters to decide on what decompression you need to do.

What we do instead is to work with slightly different models that allow us to identify the decompression that is needed based on average depth and bottom time. Therefore an expensive computer is not necessary.

Picking up on your point about wanting to start out with the tools that you'll end up using, you may find that quite a few technical divers who aren't DIR also use bottom timers instead of computers and follow tables on slates having planned the dive on the surface.

**GLOC** · June 17th, 2009, 09:36 AM

Having spent a weekend with an experience IANTD Adv Trimix IT, I found out that he doesn't teach computers on his courses until he gets to Adv Trimix. Anything before that is tables and bottom timers...

Learn what is happening, not follow something "blindly"

andriyuk · June 17th, 2009, 09:49 AM

Quote: (Originally Posted by Jack911)

You don't carry computers? Seriously?

I'm intrigued. Can someone please explain how a bottom timer is safer than a computer?

I have a very similar dive history to you. I am padi rescue 100 dives. The idea of diving without a computer seemed crazy alright.

I have then gone and done TDi advanced nitrox and decompression procedures. We actually did not use a computer on both courses. We used v-planner, then wrote everying on wet notes and then dived this plan. my instructor had x liquidvision but only as a backup. The question i asked what happens if you lose your computer or it breaks. Yes you could have a back up one but $ starts to add up. His answer was we only use it as a back up but otherwise rely on the diveplan.

I thought a lot about buying liquivision thing but then instead used cash to do Fundamentals course. i do not know anythign about your skills but no computer can replace what you will learn on the fundamentals course. so have a look into it. you can go further and do tech-1 where they teach you how to do deco in your head. all these guys do it and stay alive so it must work!

**Frank Griga** · June 17th, 2009, 10:18 AM

Quote: (Originally Posted by Jack911)

I was trying to ascertain what computer would carry me through the whole Tech learning process.

Your BRAIN would certainly carry you through the whole TECH learning process. It is cheapest alternative available and reliable.

**keri.lewis** · June 17th, 2009, 10:27 AM

Like many people entering the technical diving realm, I bought a lot of equipment that I don't use any more (Bungy wings, upstream regulators etc. etc.) I do have a VR3 that I bought some time ago. I now use it every day - it's a paperweight on my desk. I dive a gauge now. Why? you may ask..

I was diving the VR3 as a back-up to tables. It quit on me 3 times in dives - I don't just mean - you missed a stop, use tables - I mean quit..

I have dived with people using computers in the past. I find that the algorithms on the computers are either way too fast or way too padded for my body. I once waited 25 minutes on the deco bar (breathing 50% and getting bored) for a buddy's computer to clear on a repetitive 65M dive..

Now I try for simplicity in everything I use in diving. If it's a big dive - I may carry a second bottom timer, but the gauge and the plan do everything I need. The wetnotes carry the bailout/contingency plans, and a calculation sheet for RD..

IMO - A gauge is the simplest way to solve the problem - and is pretty cheap too boot.. the paperweight reminds me to think several times before buying any new gear.

deepocean · June 17th, 2009, 10:40 AM

This is exactly my thought too. When I think about it I feel much more safe if I know I have to rely on skills that I have trained for and paid for through a training course than a computer. I have seen my buddies Apeks computer lock up a couple of times in fresh and undeep waters.

This way I feel much more in control than using a computer. But then again one of my degrees is one in computer science and perhaps that is exactly why I don't trust any computer that I cannot toss out at any time in any place.

Personally, I think in general: high tech electronics under water is a bit scary for me.

Quote: (Originally Posted by andriyuk)

I have a very similar dive history to you. I am padi rescue 100 dives. The idea of diving without a computer seemed crazy alright.

I have then gone and done TDi advanced nitrox and decompression procedures. We actually did not use a computer on both courses. We used v-planner, then wrote everying on wet notes and then dived this plan. my instructor had x liquidvision but only as a backup. The question i asked what happens if you lose your computer or it breaks. Yes you could have a back up one but $ starts to add up. His answer was we only use it as a back up but otherwise rely on the diveplan.

I thought a lot about buying liquivision thing but then instead used cash to do Fundamentals course. i do not know anythign about your skills but no computer can replace what you will learn on the fundamentals course. so have a look into it. you can go further and do tech-1 where they teach you how to do deco in your head. all these guys do it and stay alive so it must work!

Niko · June 17th, 2009, 01:21 PM

Quote: (Originally Posted by Jack911)

I'm intrigued. Can someone please explain how a bottom timer is safer than a computer?

Sure.
To really understand how decompression works you need to work with it. Design your own tables, change the parameters to your personal needs, play with ratio deco and you will know a lot more about decompression than any gadget will ever know. Despite from that every human body decompresses different, every dive is different (e.g. temperature, task load) and every day is different. If you listen to your body and know how a nice deco curve can be created, you can modify the decompression to your individual needs. A computer can't do this. But he can let you hang and he will do one day. And if you don't know what to do on that day, you'll have a problem.

Here is a nice example for a ratio deco decompression for a 62m dive with 111 min total time. We did the deco calculation on the fly, based on the data from our bottom timers and our experience. The red lines show the different tissues, the blue one is the M-value line (the tissue which is nearest to critical supersaturation).

I doubt if any computer could do better ;-)

andriyuk · June 17th, 2009, 01:38 PM

Quote: (Originally Posted by Niko)

Sure.
To really understand how decompression works you need to work with it. Design your own tables, change the parameters to your personal needs, . If you listen to your body and know how a nice deco curve can be created, you can modify the decompression to your individual needs. ).

the issue for me is that i think it is really hard for someone new to know how to find out how "deco feels". How do you actually find out how to build this curve? do you need to run some profiles on deco planner, dive them and see how you feel? that is why giving up a computer seems such a hard idea.

wilbo · June 17th, 2009, 01:43 PM

andriyuk · June 17th, 2009, 01:45 PM

what do you guys do when you go for a simple 18m reef dive somewhere nice and warm? Do you also run the decoplanner and dive the plan? I have not been taught deco ratios on the fly method so i cannot really think of anything else but the planner.

would you actually consider using a simple computer on such a dive?

June 17th, 2009, 09:36 AM	#22 (permalink)
GLOC(Offline) Moderator Join Date: Nov 2005 Location: Fleet, Hants Posts: 2,692	Having spent a weekend with an experience IANTD Adv Trimix IT, I found out that he doesn't teach computers on his courses until he gets to Adv Trimix. Anything before that is tables and bottom timers... Learn what is happening, not follow something "blindly" __________________ Gareth Images of Life Photography DIR Team Foxturd Travels Underwater and Further Afar “Set your expectations high; find men and women whose integrity and values you respect; get their agreement on a course of action; and give them your ultimate trust.” “It is far better to be trusted and respected that it is to be liked.”

June 17th, 2009, 10:27 AM	#25 (permalink)
keri.lewis (Online) Wreck Ferret Join Date: Nov 2007 Location: Hampshire Posts: 930	Like many people entering the technical diving realm, I bought a lot of equipment that I don't use any more (Bungy wings, upstream regulators etc. etc.) I do have a VR3 that I bought some time ago. I now use it every day - it's a paperweight on my desk. I dive a gauge now. Why? you may ask.. I was diving the VR3 as a back-up to tables. It quit on me 3 times in dives - I don't just mean - you missed a stop, use tables - I mean quit.. I have dived with people using computers in the past. I find that the algorithms on the computers are either way too fast or way too padded for my body. I once waited 25 minutes on the deco bar (breathing 50% and getting bored) for a buddy's computer to clear on a repetitive 65M dive.. Now I try for simplicity in everything I use in diving. If it's a big dive - I may carry a second bottom timer, but the gauge and the plan do everything I need. The wetnotes carry the bailout/contingency plans, and a calculation sheet for RD.. IMO - A gauge is the simplest way to solve the problem - and is pretty cheap too boot.. the paperweight reminds me to think several times before buying any new gear. __________________ Even a "bad" day diving beats a day in the office... Keri The more I learn.. the more ignorant I realise I am..

June 17th, 2009, 01:21 PM	#27 (permalink)
Niko(Offline) New Member Join Date: Jun 2006 Location: Hannover, Germany Posts: 129	Quote: (Originally Posted by Jack911) I'm intrigued. Can someone please explain how a bottom timer is safer than a computer? Sure. To really understand how decompression works you need to work with it. Design your own tables, change the parameters to your personal needs, play with ratio deco and you will know a lot more about decompression than any gadget will ever know. Despite from that every human body decompresses different, every dive is different (e.g. temperature, task load) and every day is different. If you listen to your body and know how a nice deco curve can be created, you can modify the decompression to your individual needs. A computer can't do this. But he can let you hang and he will do one day. And if you don't know what to do on that day, you'll have a problem. Here is a nice example for a ratio deco decompression for a 62m dive with 111 min total time. We did the deco calculation on the fly, based on the data from our bottom timers and our experience. The red lines show the different tissues, the blue one is the M-value line (the tissue which is nearest to critical supersaturation). I doubt if any computer could do better ;-) __________________ trimix-nord.de Last edited by Niko; June 17th, 2009 at 01:38 PM..

June 17th, 2009, 01:43 PM	#29 (permalink)
wilbo(Offline) Senior Chimp Join Date: Nov 2005 Location: UK Posts: 1,504	__________________ Cheers! Wilbo DIR explorers: DIR Yorkshire Divers: YorkshireDivers One of the Foxturd chimps

June 17th, 2009, 09:32 AM	#21 (permalink)
neilh (Online) Wreck Enthusiast Join Date: Nov 2005 Location: Barnsley, UK Posts: 2,596	Quote: (Originally Posted by Jack911) You don't carry computers? Seriously? Yup, seriously. Well, ish Technically I (and many others) do wear a dive computer - but as someone posted earlier it's set in gauge mode so during the dive all it tells me is the depth, time and temperature. After the dive I can access the logs on it or download the profiles to my PC - but it's not being used to compute anything during the dive. Quote: (Originally Posted by Jack911) I'm intrigued. Can someone please explain how a bottom timer is safer than a computer? Is it any less safe? A computer is looking at the gas you've told it you're using, your depth and your time and applying whatever model it's designed with to those parameters to decide on what decompression you need to do. What we do instead is to work with slightly different models that allow us to identify the decompression that is needed based on average depth and bottom time. Therefore an expensive computer is not necessary. Picking up on your point about wanting to start out with the tools that you'll end up using, you may find that quite a few technical divers who aren't DIR also use bottom timers instead of computers and follow tables on slates having planned the dive on the surface.

June 17th, 2009, 09:49 AM	#23 (permalink)
andriyuk(Offline) New Member Join Date: Apr 2008 Location: London, UK/Moscow, Russia Posts: 74	Quote: (Originally Posted by Jack911) You don't carry computers? Seriously? I'm intrigued. Can someone please explain how a bottom timer is safer than a computer? I have a very similar dive history to you. I am padi rescue 100 dives. The idea of diving without a computer seemed crazy alright. I have then gone and done TDi advanced nitrox and decompression procedures. We actually did not use a computer on both courses. We used v-planner, then wrote everying on wet notes and then dived this plan. my instructor had x liquidvision but only as a backup. The question i asked what happens if you lose your computer or it breaks. Yes you could have a back up one but $ starts to add up. His answer was we only use it as a back up but otherwise rely on the diveplan. I thought a lot about buying liquivision thing but then instead used cash to do Fundamentals course. i do not know anythign about your skills but no computer can replace what you will learn on the fundamentals course. so have a look into it. you can go further and do tech-1 where they teach you how to do deco in your head. all these guys do it and stay alive so it must work!

June 17th, 2009, 10:18 AM	#24 (permalink)
Frank Griga(Offline) DIRX Supporter Join Date: Aug 2006 Location: Ireland Posts: 275	Quote: (Originally Posted by Jack911) I was trying to ascertain what computer would carry me through the whole Tech learning process. Your BRAIN would certainly carry you through the whole TECH learning process. It is cheapest alternative available and reliable.

June 17th, 2009, 10:40 AM	#26 (permalink)
deepocean(Offline) New Member Join Date: May 2008 Location: The Netherlands Posts: 82	This is exactly my thought too. When I think about it I feel much more safe if I know I have to rely on skills that I have trained for and paid for through a training course than a computer. I have seen my buddies Apeks computer lock up a couple of times in fresh and undeep waters. This way I feel much more in control than using a computer. But then again one of my degrees is one in computer science and perhaps that is exactly why I don't trust any computer that I cannot toss out at any time in any place. Personally, I think in general: high tech electronics under water is a bit scary for me. Quote: (Originally Posted by andriyuk) I have a very similar dive history to you. I am padi rescue 100 dives. The idea of diving without a computer seemed crazy alright. I have then gone and done TDi advanced nitrox and decompression procedures. We actually did not use a computer on both courses. We used v-planner, then wrote everying on wet notes and then dived this plan. my instructor had x liquidvision but only as a backup. The question i asked what happens if you lose your computer or it breaks. Yes you could have a back up one but $ starts to add up. His answer was we only use it as a back up but otherwise rely on the diveplan. I thought a lot about buying liquivision thing but then instead used cash to do Fundamentals course. i do not know anythign about your skills but no computer can replace what you will learn on the fundamentals course. so have a look into it. you can go further and do tech-1 where they teach you how to do deco in your head. all these guys do it and stay alive so it must work!

June 17th, 2009, 01:38 PM	#28 (permalink)
andriyuk(Offline) New Member Join Date: Apr 2008 Location: London, UK/Moscow, Russia Posts: 74	Quote: (Originally Posted by Niko) Sure. To really understand how decompression works you need to work with it. Design your own tables, change the parameters to your personal needs, . If you listen to your body and know how a nice deco curve can be created, you can modify the decompression to your individual needs. ). the issue for me is that i think it is really hard for someone new to know how to find out how "deco feels". How do you actually find out how to build this curve? do you need to run some profiles on deco planner, dive them and see how you feel? that is why giving up a computer seems such a hard idea.

June 17th, 2009, 01:45 PM	#30 (permalink)
andriyuk(Offline) New Member Join Date: Apr 2008 Location: London, UK/Moscow, Russia Posts: 74	what do you guys do when you go for a simple 18m reef dive somewhere nice and warm? Do you also run the decoplanner and dive the plan? I have not been taught deco ratios on the fly method so i cannot really think of anything else but the planner. would you actually consider using a simple computer on such a dive?