A Dive Computer for the Tech Newbie - Page 5

wilbo · June 17th, 2009, 03:43 PM

Quote: (Originally Posted by andriyuk)

Thanks John

What do other people feel/do?
Perhaps people who has just done their fundies?

John hit the nail on the head. If you're somewhere warm, doing recreational diving - then you will be given a single tank ~ AL80 size. Your amount of available gas means that you would be out of gas before you need to start thinking about your deco.

Change that to twin 12s, in 4C water for an hour - and you'd change things.

My reference to min deco above is what we do at the end of training dives as a matter of course.. It would do no harm - but wouldn't be necessary - especially if your out having fun on holiday..

**neilh** · June 17th, 2009, 04:05 PM

Wot they said

Hopefully you remember your min deco ascent profile and minimum gas calculations from Fundies so that's the basics sorted. Even if you look at using twin 12s for an 18m dive you're probably going to hit minimum gas before going beyond min deco.

If you have an appreciation of what times you can do at various depths and still stay within min deco limits and what your minimum gas would be then you only really need to analyse your gas on the surface so you can confirm your MOD. The amount of gas you have available (above minimum gas) defines the amount of time you can spend at depth and if you track your depth and time you'll know if you're within min deco limits.

As has been pointed out on an 18m dive you'll be hitting minimum gas - so during the dive you'll have kept an eye on your depth, time and gas to make sure and you'll be thumbing the dive on min gas.

DecoPlanner will allow you to generate tables for various depths and runtimes that not only shows when you would start to get into deco, but can show you when you would have insufficient gas based on your settings. If you have a play you'll probably find a range of depths where you're going to be pretty hard pushed to get into deco on 32% unless you take a bucket load of gas down with you

**Alastair** · June 17th, 2009, 05:32 PM

Quote: (Originally Posted by andriyuk)

so would you actually use the tables to plan it?

Planning is not something I have ever worried about as with my pre fundies diving you just listened to the DM briefing, jumped in, watched your computer. the job is done.

I am now a lot more cautious after the fundies. but i will be honest i have not actually done any diving after i finished my course in May. and somehow i just cannot rememeber for the life of me what was said about simple recreational dive planning from the deco limits/timing point of view. (i hope this makes sence).

There is a rough guide in the 30 at 30 on 32 rule. It states you have 30mins of NDL at 30m diving on nitrox 32. At the end of the dive you make a minimum deco ascent.

For every 3m shallower you get 5mins more NDL. i.e.

30m = 30mins
27m = 35mins
24m = 40mins
21m = 45mins
18m = 50mins

In fact this gets massively conservative as you get shallower. You could actually do 100mins at 18m with a minimum deco profile. By the time you get shallower than 18m then your limiting factor would always be gas in a single tank.

I'm sure there are some other posts on no-deco recreational diving somewhere so it's probably worth searching. Put the above into deco planner and see what you find. The patterns you get particularly if you play with table creation often become apparent.

Cheers
Al

***Fiona*** · June 17th, 2009, 05:57 PM

Quote: (Originally Posted by neilh)

Hopefully you remember your min deco ascent profile and minimum gas calculations from Fundies so that's the basics sorted. Even if you look at using twin 12s for an 18m dive you're probably going to hit minimum gas before going beyond min deco.

As has been pointed out on an 18m dive you'll be hitting minimum gas - so during the dive you'll have kept an eye on your depth, time and gas to make sure and you'll be thumbing the dive on min gas.

I recall min gas for a 18m dive being 40 bar, which means I would probably get bored before reaching min gas.

Anders Knudsen · June 17th, 2009, 07:54 PM

Quote: (Originally Posted by Alastair)

There is a rough guide in the 30 at 30 on 32 rule. It states you have 30mins of NDL at 30m diving on nitrox 32. At the end of the dive you make a minimum deco ascent.

For every 3m shallower you get 5mins more NDL. i.e.

30m = 30mins
27m = 35mins
24m = 40mins
21m = 45mins
18m = 50mins

In fact this gets massively conservative as you get shallower. You could actually do 100mins at 18m with a minimum deco profile. By the time you get shallower than 18m then your limiting factor would always be gas in a single tank.

Cheers
Al

where does that come from ? isent that applying ratio deco strategy to MDL dives ?

I was taught to use different "set points" and then work my way from there.

So if I rember some simple numbers.
EAN32
30min at 30m
60min at 20m
then 25 has to be somewhere in between =45min

for Air
10min at 40m
20min at 30m
45min at 20m
then 25 has to be somewhere in between = 32.5
then 35 would be - you guessed it 15min :-)

easy to remember and covers everything you need.

best

Anders

Devon Rob · June 17th, 2009, 09:09 PM

Quote: (Originally Posted by Anders Knudsen)

for Air
10min at 40m
20min at 30m
easy to remember and covers everything you need.

and some stuff you don`t

Anders Knudsen · June 17th, 2009, 09:15 PM

Quote: (Originally Posted by Devon Rob)

and some stuff you don`t

sure - I dont dive air to 30 or 40m, but I gues it works pretty well for 21/35 :-) it would not be the first time i use a 21/35 at a 20m wreck because the 45m dive was blown out.

**Alastair** · June 18th, 2009, 01:29 PM

Quote: (Originally Posted by Anders Knudsen)

where does that come from ? isent that applying ratio deco strategy to MDL dives ?

I was taught to use different "set points" and then work my way from there.
...

I think it was from Andrew Georgitsis and yes it's ratio deco style approach to MDL dives.

I play with ratios for a lot of my diving - it's quite handy.

Cheers
Al

Anders Knudsen · June 18th, 2009, 01:59 PM

Quote: (Originally Posted by Alastair)

I think it was from Andrew Georgitsis and yes it's ratio deco style approach to MDL dives.

I play with ratios for a lot of my diving - it's quite handy.

Cheers
Al

It is rather conservative - but sure that is a good thing, I just wondered as I was corrected trying to use that method in my fundy class some years ago, dident know GUE changed it.

June 17th, 2009, 03:43 PM	#41 (permalink)
wilbo(Offline) Senior Chimp Join Date: Nov 2005 Location: UK Posts: 1,562	Quote: (Originally Posted by andriyuk) Thanks John What do other people feel/do? Perhaps people who has just done their fundies? John hit the nail on the head. If you're somewhere warm, doing recreational diving - then you will be given a single tank ~ AL80 size. Your amount of available gas means that you would be out of gas before you need to start thinking about your deco. Change that to twin 12s, in 4C water for an hour - and you'd change things. My reference to min deco above is what we do at the end of training dives as a matter of course.. It would do no harm - but wouldn't be necessary - especially if your out having fun on holiday.. __________________ Cheers! Wilbo DIR explorers: DIR Yorkshire Divers: YorkshireDivers One of the Foxturd chimps

June 17th, 2009, 05:32 PM	#43 (permalink)
Alastair(Offline) DIRX Supporter Join Date: Nov 2005 Location: UK Posts: 771	Quote: (Originally Posted by andriyuk) so would you actually use the tables to plan it? Planning is not something I have ever worried about as with my pre fundies diving you just listened to the DM briefing, jumped in, watched your computer. the job is done. I am now a lot more cautious after the fundies. but i will be honest i have not actually done any diving after i finished my course in May. and somehow i just cannot rememeber for the life of me what was said about simple recreational dive planning from the deco limits/timing point of view. (i hope this makes sence). There is a rough guide in the 30 at 30 on 32 rule. It states you have 30mins of NDL at 30m diving on nitrox 32. At the end of the dive you make a minimum deco ascent. For every 3m shallower you get 5mins more NDL. i.e. 30m = 30mins 27m = 35mins 24m = 40mins 21m = 45mins 18m = 50mins In fact this gets massively conservative as you get shallower. You could actually do 100mins at 18m with a minimum deco profile. By the time you get shallower than 18m then your limiting factor would always be gas in a single tank. I'm sure there are some other posts on no-deco recreational diving somewhere so it's probably worth searching. Put the above into deco planner and see what you find. The patterns you get particularly if you play with table creation often become apparent. Cheers Al __________________ Helium is our friend - GI3

June 17th, 2009, 05:57 PM	#44 (permalink)
*Fiona*(Offline) Sister of Darkness Join Date: Sep 2006 Location: North West Posts: 1,978	Quote: (Originally Posted by neilh) Hopefully you remember your min deco ascent profile and minimum gas calculations from Fundies so that's the basics sorted. Even if you look at using twin 12s for an 18m dive you're probably going to hit minimum gas before going beyond min deco. As has been pointed out on an 18m dive you'll be hitting minimum gas - so during the dive you'll have kept an eye on your depth, time and gas to make sure and you'll be thumbing the dive on min gas. I recall min gas for a 18m dive being 40 bar, which means I would probably get bored before reaching min gas. __________________ Fiona It is impossible to make everything foolproof because fools are so ingenious. GUE Member DIVELIFE for everything you need and more

June 17th, 2009, 07:54 PM	#45 (permalink)
Anders Knudsen(Offline) I dont do fish Join Date: Dec 2005 Location: Denmark Posts: 271	Quote: (Originally Posted by Alastair) There is a rough guide in the 30 at 30 on 32 rule. It states you have 30mins of NDL at 30m diving on nitrox 32. At the end of the dive you make a minimum deco ascent. For every 3m shallower you get 5mins more NDL. i.e. 30m = 30mins 27m = 35mins 24m = 40mins 21m = 45mins 18m = 50mins In fact this gets massively conservative as you get shallower. You could actually do 100mins at 18m with a minimum deco profile. By the time you get shallower than 18m then your limiting factor would always be gas in a single tank. Cheers Al where does that come from ? isent that applying ratio deco strategy to MDL dives ? I was taught to use different "set points" and then work my way from there. So if I rember some simple numbers. EAN32 30min at 30m 60min at 20m then 25 has to be somewhere in between =45min for Air 10min at 40m 20min at 30m 45min at 20m then 25 has to be somewhere in between = 32.5 then 35 would be - you guessed it 15min :-) easy to remember and covers everything you need. best Anders __________________ Best regards Anders Knudsen www.Gadevang-UE.dk

June 17th, 2009, 09:09 PM	#46 (permalink)
Devon Rob(Offline) not a new member Join Date: Mar 2006 Location: Lyme Bay.Devon.UK formerly Hamburg, Ger. Posts: 538	Quote: (Originally Posted by Anders Knudsen) for Air 10min at 40m 20min at 30m easy to remember and covers everything you need. and some stuff you don`t __________________ this mail was checked for viruses,worms & bad breath

June 17th, 2009, 04:05 PM	#42 (permalink)
neilh(Offline) Wreck Enthusiast Join Date: Nov 2005 Location: Barnsley, UK Posts: 2,667	Wot they said Hopefully you remember your min deco ascent profile and minimum gas calculations from Fundies so that's the basics sorted. Even if you look at using twin 12s for an 18m dive you're probably going to hit minimum gas before going beyond min deco. If you have an appreciation of what times you can do at various depths and still stay within min deco limits and what your minimum gas would be then you only really need to analyse your gas on the surface so you can confirm your MOD. The amount of gas you have available (above minimum gas) defines the amount of time you can spend at depth and if you track your depth and time you'll know if you're within min deco limits. As has been pointed out on an 18m dive you'll be hitting minimum gas - so during the dive you'll have kept an eye on your depth, time and gas to make sure and you'll be thumbing the dive on min gas. DecoPlanner will allow you to generate tables for various depths and runtimes that not only shows when you would start to get into deco, but can show you when you would have insufficient gas based on your settings. If you have a play you'll probably find a range of depths where you're going to be pretty hard pushed to get into deco on 32% unless you take a bucket load of gas down with you

June 17th, 2009, 09:15 PM	#47 (permalink)
Anders Knudsen(Offline) I dont do fish Join Date: Dec 2005 Location: Denmark Posts: 271	Quote: (Originally Posted by Devon Rob) and some stuff you don`t sure - I dont dive air to 30 or 40m, but I gues it works pretty well for 21/35 :-) it would not be the first time i use a 21/35 at a 20m wreck because the 45m dive was blown out. __________________ Best regards Anders Knudsen www.Gadevang-UE.dk

June 18th, 2009, 01:29 PM	#48 (permalink)
Alastair(Offline) DIRX Supporter Join Date: Nov 2005 Location: UK Posts: 771	Quote: (Originally Posted by Anders Knudsen) where does that come from ? isent that applying ratio deco strategy to MDL dives ? I was taught to use different "set points" and then work my way from there. ... I think it was from Andrew Georgitsis and yes it's ratio deco style approach to MDL dives. I play with ratios for a lot of my diving - it's quite handy. Cheers Al __________________ Helium is our friend - GI3

June 18th, 2009, 01:59 PM	#49 (permalink)
Anders Knudsen(Offline) I dont do fish Join Date: Dec 2005 Location: Denmark Posts: 271	Quote: (Originally Posted by Alastair) I think it was from Andrew Georgitsis and yes it's ratio deco style approach to MDL dives. I play with ratios for a lot of my diving - it's quite handy. Cheers Al It is rather conservative - but sure that is a good thing, I just wondered as I was corrected trying to use that method in my fundy class some years ago, dident know GUE changed it. __________________ Best regards Anders Knudsen www.Gadevang-UE.dk