Planning the dive and slates etc, etc... [Archive]

Rowly

14-01-2010, 12:27

Dear reader,
I have recently qualified as OD and am studying and training toward SD.
Throughout our training we used tables and learnt to plan our dives etc.
It would seem that most divers just go with their computers.

I have a computer but still want to carry a DIVE CONDUCT SLATE.

I don't know if I should buy the Nitrox tables, which come with the slate (this includes the level 1 air tables). £18 is a bit steep, particularly if I use some other table or algorithm to plan on (I have read loads of debate on all this.....)

I see that there are all sorts of blank slates, wet notes and so on.

Do you use any of the BSAC products, including the slide rule computer whatsit? Are they robust and what's best to write with?

Have you managed to overlay the Dive conduct table onto a blank slate? How would I do this so that it is permanent?

I know this is very novice like stuff but hey this is the place right?
Kind regards,
Rowly

Woz

14-01-2010, 12:34

I use a set of IANTD wetnotes stuck in a pocket with a Croquis pencil, 6B. Cost you about £15 for both.

http://cgi.ebay.co.uk/IANTD-Wet-Notes_W0QQitemZ280449053092QQcmdZViewItemQQimsxq20 100110?IMSfp=TL100110234002r27355

http://www.cultpens.com/acatalog/Pilot_Croquis_Artists_Pencils.html

northern_diver

14-01-2010, 12:54

Hi Rowley,

True enough many divers do use the computer to calculate deco obligations, however, we are taught to use the respective tables of our agency (our's of course been the '88's) for a couple of reason's however. Both are still in regular use and are useful planning tools. The tables are often a little more conservative, due to the nature of how ever work, were as computers are more accurate. But that doesnt make either 'right' per say.

-As a fail back set if the computers die (either on land-great- or under water-not as great), this way be can consult a mini-table or a conduct table that some people carry. These mini-tables have either a limited amout on table data on, which ou can plot your dive or like the conduct slates, have a 'slightly deeper', 'slightly longer', 'worse case' set of data on (based on dive site specific information) than can be used. You need to have a secondary time keeper for this, a diving watch will do fine, to plan how ong you been down and time your stops.

-As a planning tool, while not as accurate as the computers as one works off a dynamic plan and one (the tables) works off a so called 'square' profile, they are still very handy. The table allow you to see a estimated dive profile, in terms of how long you will be down (with your deco) at given depths, this allows estimated gas provisons to be made as well as other dive planning, such as suitablity of dive for equipment or divers present. You might simply find your planned dive is too long for the amount fo experience or gas you can/want to take.

The '88 can be picked up from the website or some members sell them on every now and again. If memory serves, the old issues of the '88 had a mini table in, the new issues only have a conduct table in. Dont quote me however. The nitrox tables have a conduct table in and also air (nitrox 21) tables...but with out any provision for altitude. The '88 do have altitude provision in however.

Some people with experience of other agencies use other table's, which is fine as they are likely trained in them, i would recommend getting used to 1 set, before moving to another. But cherry picking skills/idea's from different organisations isnt a bad thing.

You can buy seperate conduct slates from BSAC.com as well as the tables-
http://www.bsac.com/shop.asp?section=000100010044&permissionserror=2&itemid=2557
You can also buy the tables here-
http://www.bsac.com/shop.asp?section=1362&sectionTitle=Decompression+Tables

Seems that the mini-tables are sold as Deco solution calculators, handy, but the conduct slate and table..with good dive planning practice should be all you need.

HTH

John

Edward

14-01-2010, 13:30

Dear reader,
I have recently qualified as OD
Congratulations.
I see that there are all sorts of blank slates, wet notes and so on.

Do you use any of the BSAC products, including the slide rule computer whatsit? Are they robust and what's best to write with?

Have you managed to overlay the Dive conduct table onto a blank slate? How would I do this so that it is permanent?
In the past I have ruled up, in ink, pages of a waterproof notebook. I then enter the details in pencil which can be rubbed out so the page can be used a number of times. To make it easier to find the right page underwater I use Post Office elastic bands (they don’t last long but grow all over the place).
I know this is very novice like stuff but hey this is the place right?
Kind regards,
Rowly

Right.

Regards

Edward

Nigel Hewitt

14-01-2010, 14:10

I have recently qualified as OD and am studying and training toward SD.
Well done...
Throughout our training we used tables and learnt to plan our dives etc.
It would seem that most divers just go with their computers.

Tables are about understanding but computers are about convenient.

I have a computer but still want to carry a DIVE CONDUCT SLATE.
I see that there are all sorts of blank slates, wet notes and so on.

Wet notes. And buy a pack of cheap supermarket plastic propelling pencils, they're a couple of quid for 10 or so, and use them and chuck them away when they break or the rubber falls out.
I know this is very novice like stuff but hey this is the place right?
Exactly. And these are the sort of things that can't go in the course notes or they'd be huge but you can pick up from other divers.

Rowly

17-01-2010, 17:37

Woz,
thanks for the links. I looked at this stuff and then researched it and found a similar thread over at Yorkshire Divers. Someone recommended this stuff there:
http://www.outdoorgb.com/p/web-tex_a6_notepad_holder/
With a couple of spare pads it all comes to a reasonable price.
I shall then get some soft retracting pencils as suggested and (as suggested by Edward) draw the dive conduct chart onto a page in ink.

Thanks everyone.
Rowly

Alex Liddon

17-01-2010, 21:40

I did ask the question at the DOC (or BSAC Conference) why the 88 tables were not included in the Ocean & Nitrox tables included in the Sports Diver training packs.

Never got a satisfactory answer.

I cant see the point of the student paying £25 for the pack, starting lessons and being told oh yes your going to have to fork out for tables.

Yes we do have some club ones for use in lessons, but these have gone walkies in the past and we end up having to buy replacements.

I know "everybody" uses a computer, but come on would it cost that much to include them?

How about printing them in the Diving Manual - I have a copy of the 1970 Diving Manual and they are in the Appendix. (or they would be if my copy didn't have them removed)

Vic

17-01-2010, 22:18

I know "everybody" uses a computer, but come on would it cost that much to include them?

Perhaps.

Aside from the fact that doing so would kill off any sales of tables the shop might get, I'm not entirely sure we could reprint for free - ISTR hearing that BSAC actually pays a royalty to the table developer for every copy sold. If this is the case (I'm not certain, but it came from a usually-reliable source), then that will increase the cost of the packs, and potentially give no real benefit to students.

Vic.

Nigel Hewitt

18-01-2010, 07:06

...that will increase the cost of the packs, and potentially give no real benefit to students.
But if it put a fiver on the pack and saved them twenty five on a set of plastic ones to moulder in the bottom of a dive box for years I make that a twenty pound benefit. :confused:

Isn't it time we admitted that nobody uses them in real life?

Ron MacRae

18-01-2010, 08:49

Isn't it time we admitted that nobody uses them in real life?
Not completely true. Our club uses them to determine maximum no-deco times for Ocean Divers or to show the maximum deco obligation in case of a computer failure for others. I as a DM ask for this as part of the dive plan.

Ron.

northern_diver

18-01-2010, 13:43

PADI supply the basic form of their tables i'm lead to believe (basic meaning, not the wheel or computer thingy) for use while training and diving in general.

I dont know what other agencies do however?

As a BSAC member, i would have liked my own copy of the tables, as the diving table excerts in 'the diving manual' (pages 144-145 mainly) arent great. BSAC still has to buy the tables to stock the shop etc, so the royality etc are sorted, I say stick them in the OD pack.

As for the nitrox tables, i say raise the price of the course packs alittle and stick them in, when i say alittle i mean not 18 quid of whatever they cost, but enough to pay for them and make BSAC some money. Lets help out the divers, not annoy them. As hands up, who would expect the Nitrox tables in the Nitrox course pack?

Bsac can still make money, the customer and club member can still make money and of course, the manufactor/developer can.

If you computer doesnt have a planning option..or you dont know how to use it, then a table is fine for using to plan the 'oh, s**t, my computer is dead' moments. Any faff on about technical diving can stow it too, thats a different set of requirements and not the OP's question.

To the OP, its 18 quid and once you got them, they will outlive you in terms of material...they might be replaced, but you shouldnt ever need to buy anew and they have, as you seen, been shown to be used for simpler stuff, planning and emergency.

Hope that helps,

John

PeteM

18-01-2010, 14:05

hands up, who would expect the Nitrox tables in the Nitrox course pack?

They were in the Basic (no longer taught) and combined course packs, only one they were not in was the advanced but you had to have done the basic to do that anyway

northern_diver

18-01-2010, 14:26

They were in the Basic (no longer taught) and combined course packs, only one they were not in was the advanced but you had to have done the basic to do that anyway

Thats handy, you have get them in the basic course that A) most people do as a combined course with their OD (new folks anyway) and B) no one teachs it....so in effect, you dont get them.

As the provision for getting them in a course pack has gone, then the remaining nitrox course, which is still Ad.Nitrox (as its not quite dead yet) should get them.

Must admit, the normal tables are IMO more useful. Dive nitrox, on a 88's or use the 88's for air diving. This is appling to divers which arent doing deep/long stuff especially, just 30 mins at 30metes or something close, couple mins deco on the line. No special, custom dive dives, no trimix, no 'breathers. Just an air or weak nitrox mix. Though admittibly, the nitrox tables do give you air and the choice to swap to a mix if needs be, so irrespective, a table could and IMO be included.

Dont make me buy more, just get me to pay alittle at 1st. It almost like a trick to force sales through the shop;)

John

Woz

18-01-2010, 15:07

David Cowan

18-01-2010, 23:05

Isn't it time we admitted that nobody uses them in real life?

Nigel,

In addition to planning dives, I use the BSAC 88 Tables as follows. I live in a locallity where there is a need to drive over some high hills to dive a number of sites - I find the BSAC '88 Tables very useful in calculating how long to wait before travelling back over these hills.

Regards

Gordon

19-01-2010, 09:11

R.Burgess

19-01-2010, 09:53

I must confess I can never remember how to use Buhlmann :confused: I have to look at the directions every time. :D I wonder how many people just use a 5 10 20 40 system for dive planning?

Nigel Hewitt

19-01-2010, 10:38

I must confess I can never remember how to use Buhlmann :confused: I have to look at the directions every time. :D I wonder how many people just use a 5 10 20 40 system for dive planning?
For planning I just use a card with bottom times for nostop, 5 mins deco and maxing out my bailouts for every depth in three meter intevals.

It gives me a quick handle on what I can do and I then tend to cut and stick the plan within those limits in the water on the computers.

ChristianG

19-01-2010, 21:43

Isn't it time we admitted that nobody uses them in real life?
Actually Nigel, although I agree with the sentiments of your comment I don't necessarily agree with the practicalities of it.

Computers, quite simply, make you lazy - they tell you what to do but not why you should do it. I still believe that there is nothing better than a good grounding in Dive Tables (of whatever flavour) to allow a student to understand how decompression works - theoretically anyway seeing as that is all that decompression is.

Nigel Hewitt

20-01-2010, 07:40

Computers, quite simply, make you lazy - they tell you what to do but not why you should do it. I still believe that there is nothing better than a good grounding in Dive Tables (of whatever flavour) to allow a student to understand how decompression works - theoretically anyway seeing as that is all that decompression is.
Rubbish.
We teach people to use tables like a bus time-table.
No understanding of decompression is required.

BSAC tables pretend to be simple but are in fact the most complicated beast. Plus they don't work on bottom time so they require offsets for dive planning.

Watching some poor prospective Sports Divers working out how long it is before they can drive over a hill to go home for the exam still horrifies me.

northern_diver

20-01-2010, 11:48

Rubbish.
We teach people to use tables like a bus time-table.
No understanding of decompression is required.

BSAC tables pretend to be simple but are in fact the most complicated beast. Plus they don't work on bottom time so they require offsets for dive planning.

Watching some poor prospective Sports Divers working out how long it is before they can drive over a hill to go home for the exam still horrifies me.

No understanding is required, but it is taught while your taught the tables, its in the same, and surounding modules. Atleast i was taught that and if i were to present this lecture, i would link it to current, accepted decompression theory.

BSAC tables are IMO easier to use than the RDP (i've never had to use another, thus this example), however the atlitude section (if applicable to your dive even) isnt ideal but most stressing comes from lack of skill upkeep rather than table design. Practice more often and its going to be smoother, that been said they do cause people some issues, its not mountain, much more a mole hill;)

This point of discussion is null and void, evidence has been presented that they are still in use, so they should still be taught. Fairly logical i feel people would agree.

John

Woz

20-01-2010, 13:05

The BSAC tables are a doddle to use and teach with no maths which is where Bertie Buhlmanns fall down. We don't teach the theory behind them as you don't need to know how an engine works to drive a car.

Whether you like the theory behind them or not is another matter.

In an ideal world, someone would have come up with some BSAC 88 style Buhlmann tables. I wonder who has? ;)

Rowly

20-01-2010, 13:08

Whoa, Guys....
I thought this might happen. I have read loads on here about which tables and outdatedness and so on....All I wanted to know was how I could write up my current basic and potential future more complicated plans:o

However.....Yes I agree that the tables should have been part of my induction packages. I have signed up to BSAC and trust that their products are correct (for now.)

As for bottom times and flying and whatnot I do think the BSAC tables are easy to use.
Nigel, I thought the bottom time referred to the amount of time you want to swim around the wreck etc. Isn't this catered for in the tables, e.g. 35m dive for 50 minutes requires such and such deco stops?

I have downloaded and perused H and Vplanners and they appear straightforward as does the software that came with my Suunto Vytec.

Woz

20-01-2010, 13:11

You dive time is your time from leaving the surface to the time you reach your first stop. That's why there's an "ascent time" column so you can work out your bottom time.

With most other tables the dive time is the time from surface to leaving the bottom.

PeteM

20-01-2010, 13:19

With most other tables the dive time is the time from surface to leaving the bottom.

to expand on that...

The problem with tables calculated on a leaving the bottom basis is that they have to assume a definite profile for the ascent, so if the are calculated on a 18 metres per minute ascent (as are PADI tables) and you think that this is too fast so you ascend at 8 mpm then the deco calculated is no longer correct.

The thing I like about the BSAC tables is that they do not have this restriction, you can ascend at what ever speed you like providing it is within the table limits.

Nigel Hewitt

20-01-2010, 13:20

Nigel, I thought the bottom time referred to the amount of time you want to swim around the wreck etc. Isn't this catered for in the tables, e.g. 35m dive for 50 minutes requires such and such deco stops?
Well let's make that a 37 minute air dive to 36 meters requiring 2 mins at 9 meters and 18 minutes at 6 meters.

How long can I be on the wreck?
The thing I like about the BSAC tables is that they do not have this restriction, you can ascend at what ever speed you like providing it is within the table limits.But you have to arrive on time. Other tables tell you when you should leave which I make as 10 times easier.

PeteM

20-01-2010, 13:24

Well let's make that a 37 minute air dive to 36 meters requiring 2 mins at 9 meters and 18 minutes at 6 meters.

How long can I be on the wreck?

Leave the bottom @ 35 minutes or before as it is going to take a minimum of two minutes to get from 36 to 9 @ 15mpm which comes from the ascent column if you can not work it out.

Not difficult really

northern_diver

20-01-2010, 14:37

Well let's make that a 37 minute air dive to 36 meters requiring 2 mins at 9 meters and 18 minutes at 6 meters.

How long can I be on the wreck?
But you have to arrive on time. Other tables tell you when you should leave which I make as 10 times easier.

:confused: horses for courses Nigel, You know as well as any (or should) that if you use the definations in the '88's for dive time, ascent rate, deco stops etc what that will give you.

The 'but you have to arrive on time' line isnt really especially brilliant as a criticism, as correct me if im wrong, but dont you have to run, of some sorts, to a plan on all tables? Keeping to your run times is going to be a factor whatever you do.

If your using the table then you are bound, in some way but the timing imposed within it e.g to follow your point to a logical conclusion, you have to depart on time with 'your' suggested tables...No further forward, some people get it, some people don't.

John

Vic

20-01-2010, 14:47

But if it put a fiver on the pack and saved them twenty five on a set of plastic ones to moulder in the bottom of a dive box for years I make that a twenty pound benefit.

What if it cost them twenty five to save that twenty five? And what if they already had access to the tables anyway - being as how they're in a club, and these things get passed around...

Isn't it time we admitted that nobody uses them in real life?

If we do, then it makes even less sense to enforce their purchase.

Vic.

Vic

20-01-2010, 14:49

But you have to arrive on time. Other tables tell you when you should leave which I make as 10 times easier.

I disagree.

Other tables tell you when to leave *and* you still have to arrive on time.

BSAC tables just tell you when to arrive; I make that quite a bit easier...

Vic.

Nigel Hewitt

20-01-2010, 15:04

I disagree.

Other tables tell you when to leave *and* you still have to arrive on time.

BSAC tables just tell you when to arrive; I make that quite a bit easier...
Which takes me back to the fact that almost everybody tends to use computers. The fallback on your own computer is your buddy's computer.
The fact that that might not quite match your dive means we need to understand how and when to add extra margin (safety factors).

We need to teach what people will do formally, not make them have to pick it up as they go from whoever. I saw this on the primary take thread. Nobody is taught to do primary take but we all say a good percentage faced with a problem will do it. Most will use computers and you are more likely to have a computer failure than an OOG.

I see people in angst the first time their buddy's computer doesn't agree with their's and yet it is so simple. Also gas planning a computer dive is radically different.

Woz

20-01-2010, 15:15

Let's all learn ratio deco and chuck the tables in the bin. I reckon I could teach it in about 1/2 an hour.

Vic

20-01-2010, 15:58

We need to teach what people will do formally, not make them have to pick it up as they go from whoever.

I can't argue with that - but I don't see how it's relevant to whether or not the '88s are easier to use than any other table...

Vic.

Vic

20-01-2010, 15:59

I reckon I could teach it in about 1/2 an hour.

Go on then - write a page...

Vic.

Vic

20-01-2010, 16:01

The problem with tables calculated on a leaving the bottom basis is that they have to assume a definite profile for the ascent, so if the are calculated on a 18 metres per minute ascent (as are PADI tables) and you think that this is too fast so you ascend at 8 mpm then the deco calculated is no longer correct.

I've seen it claimed that the RDP is the table most widely used for diving; I would suggest that, in fact, almost *no* dives are conducted on the RDP...

Vic.

Vic

20-01-2010, 16:16

In an ideal world, someone would have come up with some BSAC 88 style Buhlmann tables. I wonder who has? ;)

Can you send me a copy, please?

Ta!

Vic.

PeteM

20-01-2010, 17:08

I've seen it claimed that the RDP is the table most widely used for diving; I would suggest that, in fact, almost *no* dives are conducted on the RDP...

Vic.

I would agree, but the point was to illustrate the importance of a defined ascent rate on a "bottom time" table and why you might want to not follow that for which purpose it works :D

Rowly

20-01-2010, 18:16

Blimey, what have I done:confused:

northern_diver

20-01-2010, 18:32

Blimey, what have I done:confused:

Feel the shame Rowly;) :rolleyes: :p

This is, unfortunately the down side of having a mixed experience and mixed 'genre' diving forum. Ideals and protocols which are suitable for one are sometimes placed up against another where, while they can be mutually assisting, arent always and arent alwas required.

That been said, the more you know and experience, the more capable or 'correctly' applying yourself to the world.

I hope, somewhere in the midst of all the OFF TOPIC replies, you were able to find something of use.

John

Rowly

20-01-2010, 19:06

ChrisW1

20-01-2010, 19:13

I bought a set of tables last year on one side is the Dive conduct slate - the other has a grid with a mini table on.

Woz

21-01-2010, 17:41

John, and the rest,
thanks, I do like a good debate. As for things to write on I have taken a lot of sensible advice and gone for a wetnote derivative and pouch to hold it. I have also learnt that to write on it I need a softer pencil like a 6b (and I hadn't even thought of that!).

I also learnt that I can draw the conduct slate on my wet paper so don't have to buy this.

As for tables it's terribly complicated but to keep things simple at my level of experience I will plan dives as taught. Write it all down in case my computer fails and I lose my buddy!

At the moment this allows me to calculate how long I can dive for and how much air I will need.That's fine for dive 1. But what do you do for dive 2 when the tables and your computer are miles apart? Or dive 3?
And on a multi-day trip, then what? By day 4 your Suunto will still be showing residual nitrogen and your tables will be clear.
What works well at OD level is planning your dives on your computer. Write down:

Plan (NDL -3 min)
Just deeper (+3m)
Just longer (NDL)

on your slate. Repeat for the next dives.
However at SD+ level where you are planning a deco dive, most computers (there are a few exceptions) won't plan a deco dive. VR3, Uwatec Galileo are 2 that do off the top of my head but none of the Suunto range do.

I use an example where you do 2 45min dives in Stoney to 21m max with a 2hr surface interval that I did between xmas and new year a couple of weeks ago. No problem on a computer as it takes into account your profile. On air tables, it can't be done, even with deco.

northern_diver

21-01-2010, 18:21

That's fine for dive 1. But what do you do for dive 2 when the tables and your computer are miles apart? Or dive 3?
And on a multi-day trip, then what? By day 4 your Suunto will still be showing residual nitrogen and your tables will be clear.
What works well at OD level is planning your dives on your computer. Write down:

Plan (NDL -3 min)
Just deeper (+3m)
Just longer (NDL)

on your slate. Repeat for the next dives.
However at SD+ level where you are planning a deco dive, most computers (there are a few exceptions) won't plan a deco dive. VR3, Uwatec Galileo are 2 that do off the top of my head but none of the Suunto range do.

I use an example where you do 2 45min dives in Stoney to 21m max with a 2hr surface interval that I did between xmas and new year a couple of weeks ago. No problem on a computer as it takes into account your profile. On air tables, it can't be done, even with deco.

Assuming AIR and assuming A1 start code

Dive 1-

21m, 45mins = G-1 min @ 6m Deco

2 hours interval = CTC(current tissue code) C

Dive 2-

21m, 37mins (max allowed on this table) = G-2 min @ 9m + 18 min @ 6m

it only just doesnt make it, though the deco is silly for the dive benefit IMO

If worked on a interval of 4 hours however, you could do-

Dive 2

21m, 45 min =G- 1 min @ 9m + 6 min @ 6m

With up to 57 mins allowed.

Not ideal, but if using nitrox 36 for example, your dives would be as follows-

Dive 1-

21m, 45mins = D-no Deco (could have dived till 50 mins)

2 hours interval = CTC(current tissue code) C (could have as little time as 1 hours)

Dive 2-

21m, 45mins = G- 3 min @ 6m (could dive till 51 mins)

So i guess its possible, if you use the correct tools. Tables will always be less accurate than computers as, as we know, they use a simple square profil, not the significantly more accurate dynamic (for want of a better term) profile. Even without using the nitrox, the dives can be reached almost with tables. Lets not forget that OD's are qualified to use Nitrox36 straight from the stables. As for the Deco, do it on the trot, like most do and you havent a problem, under Nemo's or something.

I think that shows a slightly more fair view of the tables, with the benefits and disadvantages shown a little. As the benefits of Nitrox, the planning side of the tables used for gas requirements etc and limitations of depth and time are shown.

I dont disagree that tables should be used over computers, but that they can be used.

John

P.s I hope those are right, i just sprung those out before i go for a run, as im in a bit of a rush:rolleyes:

Woz

22-01-2010, 10:30

There is also a method of doing a multi-level dive on 88s that is outlined in Advanced Sport Diving. The point is that the dives I did were mostly at 6m for dive 1 with a quick bob down to the helicopter then dive 2 was a proper 21m dive for a furtle round the new wreck. Tables penalise you massively for this.

Either way, you should scribble down your NDL from your computer before you jump in the water. This way, you have a backup based on your actual tracked nitrogen loading rather than a massively innaccurate estimation.

Relying on your buddy's computer for anything but max depth and dive time is a no-no.