Air planing

[Mark Cowgill]

Hi all

Taking my sports diver theory lessons at the moment just wondered if one of you kind people could remind me of the air planning equation so I can study it when I have quiet periods at work, I do have the information at home but I am away from home for a while.:)
Mark.

[Chriis Heywood]

Do you mean surface usage = 25L of air per min then +25L per 10 M depth?
This is based on an average usage, Some people do breath more!
Chris

[Mark Cowgill]

Yes based on standared use of 25 ltrs per min on surface

[Gareth]

Sports Diver Theory

amount of air required = 25l/min x Absoulte pressure (bar) x time minutes
remember to add a third (reserve) (x1.5)



amount of air in cylinder = Cylinder capacity (l) x air pressure (bar)


Gareth

[Mark Cowgill]

Thank you Gareth

[Woz]

And the questions always ask "what size cylinder will you need to do dive X" which is utter bollox. You don't have a range of cylinders to choose from on a dive trip.

A much better question would be "you have a red hot 250 bar fill that you know will cool to a crappy 180 bar fill of dodgy oily air off a boat compressor in an O2 clean 12 so you're now really annoyed. How long can you dive for to 30m before getting back out with a cracking headache and puking over the side?"

Much more realistic.

[Mark Cowgill]

Gareth

Can you please check this equation for me

If my dive plan time is to dive to 30 mtrs for 20 mins on a twelve ltr cylinder at 230 bar.

25 ltrs per min at surface, at 30 mtrs I would be at 4 bar = 4 x 25 =100

100 ltrs x20 mins =2000 ltrs leaving 760 ltrs

cylinder size is 12 ltrs, capacity is 230 bar

230x12=2760

2760 devided by 3 =920

Therefore I would not have enough air when I came to surface using the rule of thirds

Am I correct or do I need to go back to the drawing board.

Mark.

[Mark Cowgill]

Crikey Woz they told me diving was fun at the club house not so sure now, If I am on a dive trip I will grab the cylinder I have planed for not bothered whos it is either:)

Mark.

[Nigel Hewitt]

If I am on a dive trip I will grab the cylinder I have planed for not bothered whos it is either:)Well the white one with the stickers is mine but as it has pure oxygen in it you probably won't live long enough at 30meters to run out.

[Mark Cowgill]

Got that Nigel,I meant any cylinder except the white one with stickers on it:)

Mark

[Dave Bewick]

Gareth
Can you please check this equation for me
If my dive plan time is to dive to 30 mtrs for 20 mins on a twelve ltr cylinder at 230 bar.
25 ltrs per min at surface, at 30 mtrs I would be at 4 bar = 4 x 25 =100
100 ltrs x20 mins =2000 ltrs leaving 760 ltrs
cylinder size is 12 ltrs, capacity is 230 bar
230x12=2760
2760 devided by 3 =920
Therefore I would not have enough air when I came to surface using the rule of thirds
Am I correct or do I need to go back to the drawing board.

Mark.

BSAC recommends you have at least 25% cylinder capacity as a reserve, so use 2760/4 not 2760/3. This means you need 2000lt + 690lt which is within your 2760lt total. Practically this leaves you surfacing with about 63Bar which is fine. The old rule of thirds (1/3 no clear surface, 1/3 clear surface 1/3 reserve) has been overtaken by events as most no clear surface diving involves more than one cylinder (or at least mine does!).

[Mark Cowgill]

Thanks Dave but will I pass the exam using this method as I dont think this information has filtered through to our club yet.is it possible that our instructors are using the old method and when the test paper is put in front of us it will be the new method which sounds like the rule of 1/4s to me. by the way was my calculation correct.

[Dave Bewick]

Thanks Dave but will I pass the exam using this method as I dont think this information has filtered through to our club yet.is it possible that our instructors are using the old method and when the test paper is put in front of us it will be the new method which sounds like the rule of 1/4s to me. by the way was my calculation correct.

Your calcs were fine. Check out Safe Diving Practices at: http://www.bsac.org/techserv/sdp.htm under Air Reserve.

I don't have my instructor manual with me at the moment, but I will check my facts tomorrow and post anything I think I have missed.

[Nick Kay]

Just be careful that its not a "crafty" question and specifies a bottom-time or dive-time of xxx mins. In which case you'd need to consider the safety-stop/deco time and last part of the ascent. :rolleyes:

Not saying that BSAC Qpapers are written by that, but if you're in one of those clubs that have written their own papers and you have a crafty (aka "awkward b*****d" of a DO/TO) then... :eek:

[Paul Morris]

Can you please check this equation for me

If my dive plan time is to dive to 30 mtrs for 20 mins on a twelve ltr cylinder at 230 bar.

25 ltrs per min at surface, at 30 mtrs I would be at 4 bar = 4 x 25 =100
100 ltrs x20 mins =2000 ltrs leaving 760 ltrs
cylinder size is 12 ltrs, capacity is 230 bar
230x12=2760
2760 devided by 3 =920
Therefore I would not have enough air when I came to surface using the rule of thirds

Now, what do you think of this people....

I was taught (still do, and now teach...) that the air should be split into each phase of the dive.
Descent
Bottom Time
Ascent
Deco
Ascent from 6m (negligible but...).

For the example above:

Descent from 0m to 30m. Average absolute pressure = 2.5 bar assuming linear descent.
Air consumption on descent -> 2.5 x 25l/min = 62.5 l/min.
Time for descent = 1 min (BSAC tables max descent rate 30m/min).
Therefore descent used 62.5l.

Bottom time
Now dive time is 20min. We've already used 1min, and the ascent to 6m is going to take 2 min (rounded up). That leaves 17 min on the bottom.
Air consumption on the bottom -> 4 x 25 l/min = 100 l/min
Air used -> 100 l/min x 17min = 1700l.

Ascent phase 30m to 6m
Average abs pressure -> (0.6+4) / 2 = 2.3 bar
Average air consumption -> 2.3 x 25l/min = 57.5 l/min
Time taken to ascend is 2min (rounded up) using max ascent rate 15m/min.
Air used -> 57.5 l/min x 2min = 115l

Deco phase
30m for 20min on BSAC'88 table A is a no stop dive :eek: so, nothing here.

Ascent phase from 6m
This really is nit picking, but average abs pressure -> 1 + 1.6 /2 =1.3bar
Average air consumption -> 1.3 x 25l/min = 32.5 l/min
Ascent should take 1 min, so air used is 32.5l

Now finally, the air consumption would be:
62.5 + 1700 + 115 + 32.5 = 1910l

Your 12l cylinder filled to 230bar supplies 2760l of free air, so you have a reserve of 850l or just under 71bar.

I'd consider this ok for the dive proposed.

The rule of thirds we teach at Ocean diver level is not *the* rule of thirds. We teach:
1st third for descent and 1st part of dive (out-leg)
2nd third for the 2nd half of the dive (return-leg)
Final 3rd for the ascent & reserve.

I don't like it as it confuses with the original (and more widely known) rule of thirds, but it does simplify air planning for ocean divers. At 20m doing no stop dives, if you bother to do the maths you will always get out with more than 50bar (assuming you're not diving a pony!). In my opinion Sport divers should not be using rule of thirds, but working out the actual requirements including any deco stops, then consciously deciding on a sensible reserve value considering their dive plan. Beyond SD the real rule of thirds may be appropriate, but by that stage you should know your real Surface Air Consumption (SAC) rate which is usually far less than 25l/min.

Anyway, what do others think of this approach. Its what I was taught, and now teach. It is potentially more accurate, but taking the simple (all time on the bottom) approach does mean you build in an additional unknown reserve.

Fire at will.... :p

[PhilB]

Thanks Dave but will I pass the exam using this method as I dont think this information has filtered through to our club yet.is it possible that our instructors are using the old method and when the test paper is put in front of us it will be the new method which sounds like the rule of 1/4s to me. by the way was my calculation correct.

Yes the Safe Diving Practices says keep at least 25% reserve but if you are doing this for your Sports Diver exam I would go with what is used in the SD theory lesson examples (unless your branch instructors have told you otherwise) which is the one thirds rule.

In this case air needed for dive is 4 bar x 25 litres/minute x 20 minutes = 2000 litres

Following the rule of thirds this is two thirds of what you actually need in your cylinder (if you use 1000 out and 1000 back which makes 2000 needed for the dive you then need to add another 1000 as the reserve). You can work out the one third reserve by dividing the air needed for the dive by 2 and adding it on. Or a faster method is just multiply the air needed by 1.5

So air needed including reserve = 2000 x 1.5 = 3000 litres

Air available is 12 x 230 = 2760 litres

So not enough air for the dive (in the exam anyway)

Hope this helps,
Phil

[adrian wrighton]

IF YOU ALL TAKE THE ONES WITH THE WHITE STICKERS ON THERE WONT BE ANY TANKS LEFT FO THE OTHERS???:)

[Dave Bewick]

Your calcs were fine. Check out Safe Diving Practices at: http://www.bsac.org/techserv/sdp.htm under Air Reserve.

I don't have my instructor manual with me at the moment, but I will check my facts tomorrow and post anything I think I have missed.

OK I've looked up the book, which is exactly what PhilB said. You need to work on 2/3rds to the end of your dive at depth, and then 1/3 for the ascent and reserve. So for your dive of 20 min @ 30m using 25 lt/min a 12lt tank is not enough.

If I was marking the exam I would be far more interested in your thinking (and basic maths) than which variation of BSAC advice you were following.

[Gareth]

Paul

You right about the rule of thirds issue.

The first thing I say is this is the rule of thirds - but it isn't!

I explain the Ocean diver version, then explain the traditional version, then repeat the Ocean diver version, saying this is the one you need for the theory test. Arghhh.

Good explination about air planning :)

Gareth

[Tristan Green]

Ascent phase 30m to 6m
Average abs pressure -> (0.6+4) / 2 = 2.3 bar
Average air consumption -> 2.3 x 25l/min = 57.5 l/min
Time taken to ascend is 2min (rounded up) using max ascent rate 15m/min.
Air used -> 57.5 l/min x 2min = 115l

Now finally, the air consumption would be:
62.5 + 1700 + 115 + 32.5 = 1910l

Fire at will.... :p
Well you did invite me ... :D

I'm sure you meant to type:

Ascent phase 30m to 6m
Average abs pressure -> (1.6+4) / 2 = 2.8 bar
Average air consumption -> 2.8 x 25l/min = 70.0 l/min
Time taken to ascend is 2min (rounded up) using max ascent rate 15m/min.
Air used -> 70.0 l/min x 2min = 140l

Now finally, the air consumption would be:
62.5 + 1700 + 140 + 32.5 = 1935l

This takes nothing away from your reasoning though, but I hope this will help those who may be struggling with the arithmetic.

Cheers,
Tristan

[Edward]

Sports Diver Theory

amount of air required = 25l/min x Absolute pressure (bar) x time minutes
remember to add a third (reserve) (x1.5)

Garth,

I would be interested to know where you got the (x1.5) from, as the current Diving Manual for Sport Divers suggests using 25% (pages 64/5) not 33% as a reserve for air calculations.

I know 1/3 is used for some 'interesting' dives, but the thread was to answer questions for the SD Exam. As part of our Quality Control DOs should not be using 'other' calculation methods for exams.


Edward

[John Williams]

Gareth

Can you please check this equation for me

If my dive plan time is to dive to 30 mtrs for 20 mins on a twelve ltr cylinder at 230 bar.

25 ltrs per min at surface, at 30 mtrs I would be at 4 bar = 4 x 25 =100

100 ltrs x20 mins =2000 ltrs leaving 760 ltrs

cylinder size is 12 ltrs, capacity is 230 bar

230x12=2760

2760 devided by 3 =920

Therefore I would not have enough air when I came to surface using the rule of thirds

Am I correct or do I need to go back to the drawing board.

Mark.

Why did you divide 2760 by 3?

The air you use (i.e. 2000l) is what should be divided by three - and the result added to the air to be breathed ....to give a reserve.

(I actually find it easier to take the air breathed divide it by three and nultiply by four - to give 4/3. I think this is where the 25% or 1/3 reserve confiusion occurs. If you have four thirds then one of those four thirds is 25% of the total - but remains a third...if you get my drift!)

The rule of thirds is generally not used in "simple" recreational diving - it is more normally used on more adventurous diving - and is a concept borrowed from cave diving ...1/3 in, 1/3 out 1/3 spare - but since we can normally come straight up we don't need to plan so securely to find the way out of the cave! Deco diving etc does put an artificial "no-clear surface" above us and people have - quite reasonably - tried to make these dives as safely as possible by considering such a non-physical barrier to the surface as more solid!

2000/3 = 667 ....so your 2760 is more than enough

or

2000 x 4/3 = 2667 ...which is less than what is in your cylinder ...so you are good to go!
(as long as you definately still have 222.5+ bar in your cylinder after you dunk it in cold water!)

because 2667/12 = 222.5

HTH

John

[Dave Bewick]

Garth,

I would be interested to know where you got the (x1.5) from, as the current Diving Manual for Sport Divers suggests using 25% (pages 64/5) not 33% as a reserve for air calculations.

I know 1/3 is used for some 'interesting' dives, but the thread was to answer questions for the SD Exam. As part of our Quality Control DOs should not be using 'other' calculation methods for exams.


Edward

I think I quoted this as well after checking the Instructor Manual (2003 p 169) I have checked the Record of Changes in the Instructor area and don't think anything is changed. I don't have the lastest version of the Sport Diving Manual with me.

[Dave Bewick]

Why did you divide 2760 by 3?

The air you use (i.e. 2000l) is what should be divided by three - and the result added to the air to be breathed ....to give a reserve.

...

John

This is starting to get me confused. I think the amount of reserve being suggested at Sport Diver is a bit over the top, but this is a worked example from ST5.

Dive to 20m for 20 mins
Breathing rate x absolute pressure x time

25 l/min x 3 bar (20m) x 20 mins = 1500 litres
This represents air for dive (Two Thirds)
Add ascent and reserve third - 1500 x 1.5 = 2250 litres Total

Reserve judged against type of diving being undertaken

[PhilB]

Garth,

I would be interested to know where you got the (x1.5) from, as the current Diving Manual for Sport Divers suggests using 25% (pages 64/5) not 33% as a reserve for air calculations.

I know 1/3 is used for some 'interesting' dives, but the thread was to answer questions for the SD Exam. As part of our Quality Control DOs should not be using 'other' calculation methods for exams.


Edward

Sorry but I'm with Dave Bewick on this one. The x 1.5 is shown in the Sport Diver theory lesson ST5 (Instructor Manual 2003 p.169 and Sports Diver Student Workbook 2002 p.74). ST5 does acknowledge that this reserve can be increased or reduced depending on the conditions and depth of dive, but I suggest that for the SD Exam we should be using what is taught in the SD lesson worked examples, not what is in The Diving Manual.

I haven't checked the exam answers but hopefully they will reflect the one third reserve as per the lesson.

Phil

[Paul Morris]

Well you did invite me ... :D

I'm sure you meant to type:

Ascent phase 30m to 6m
Average abs pressure -> (1.6+4) / 2 = 2.8 bar
Average air consumption -> 2.8 x 25l/min = 70.0 l/min
Time taken to ascend is 2min (rounded up) using max ascent rate 15m/min.
Air used -> 70.0 l/min x 2min = 140l

Now finally, the air consumption would be:
62.5 + 1700 + 140 + 32.5 = 1935l

This takes nothing away from your reasoning though, but I hope this will help those who may be struggling with the arithmetic.


I knew it! :o
Was bound to happen!

Thanks.

[purdy]

Now, what do you think of this people....

I was taught (still do, and now teach...) that the air should be split into each phase of the dive.
Descent
Bottom Time
Ascent
Deco
Ascent from 6m (negligible but...).

For the example above:

SNIP

I don't like it as it confuses with the original (and more widely known) rule of thirds, but it does simplify air planning for ocean divers. At 20m doing no stop dives, if you bother to do the maths you will always get out with more than 50bar (assuming you're not diving a pony!). In my opinion Sport divers should not be using rule of thirds, but working out the actual requirements including any deco stops, then consciously deciding on a sensible reserve value considering their dive plan. Beyond SD the real rule of thirds may be appropriate, but by that stage you should know your real Surface Air Consumption (SAC) rate which is usually far less than 25l/min.

Anyway, what do others think of this approach. Its what I was taught, and now teach. It is potentially more accurate, but taking the simple (all time on the bottom) approach does mean you build in an additional unknown reserve.

Fire at will.... :p

Hurray anoher one

Yes I was taught this way for Dive leader a long time a go and was staggered that I was the only one in our club who taught it this was at that level still.

Oooh I feel so much better now

:D:D

[purdy]

Now, what do you think of this people....

I was taught (still do, and now teach...) that the air should be split into each phase of the dive.
Descent
Bottom Time
Ascent
Deco
Ascent from 6m (negligible but...).

For the example above:

SNIP

I don't like it as it confuses with the original (and more widely known) rule of thirds, but it does simplify air planning for ocean divers. At 20m doing no stop dives, if you bother to do the maths you will always get out with more than 50bar (assuming you're not diving a pony!). In my opinion Sport divers should not be using rule of thirds, but working out the actual requirements including any deco stops, then consciously deciding on a sensible reserve value considering their dive plan. Beyond SD the real rule of thirds may be appropriate, but by that stage you should know your real Surface Air Consumption (SAC) rate which is usually far less than 25l/min.

Anyway, what do others think of this approach. Its what I was taught, and now teach. It is potentially more accurate, but taking the simple (all time on the bottom) approach does mean you build in an additional unknown reserve.

Fire at will.... :p
Hurray anoher one

Yes I was taught this way for Dive leader a long time a go and was staggered that I was the only one in our club who taught it this was at that level still.

Oooh I feel so much better now

:D:D

[John Williams]

Not saying that BSAC Qpapers are written by that, but if you're in one of those clubs that have written their own papers and you have a crafty (aka "awkward b*****d" of a DO/TO) then... :eek:

...ah, but what he IS saying is that HE is a "crafty" DO!:D ;) :D

John

[John Williams]

If I was marking the exam I would be far more interested in your thinking (and basic maths) than which variation of BSAC advice you were following.

I'll second that!
...rational thinking and a sensible air management strategy is far more important than the same answer as is written in the book!

Give me sound reasoning and a "wrong" answer over a lucky guess anyday!

John

[Edward]

All

Oh dear, we appear to have two BSAC sources giving conflicting advice?

1. The Diving Manual gives 25% of the air required for the dive as the reserve.

2. ST5 gives 33% of the air required for the dive as the reserve.

I'm going to flag this one to the appropriate NDC Group for comment.

Edward

[Dave Bewick]

All

Oh dear, we appear to have two BSAC sources giving conflicting advice?

1. The Diving Manual gives 25% of the air required for the dive as the reserve.

2. ST5 gives 33% of the air required for the dive as the reserve.

I'm going to flag this one to the appropriate NDC Group for comment.

Edward

Common practice would support having at least 50bar on return to the surface. I'm not sure a proportion of the air for the dive makes much sense, much better to use a proportion of the capacity of the clyinder(s). This would be in line with Safe Diving Practices.

[Gareth]

Edward

As stated above, I pulled it straight out of the Sports Diver Vis' Aids, to ensure that it matches what should have been taught & what should be on the question paper.

The 25% you qoute is in the Ocean Diver Vis' Aids OT4. But the 'new' way its taught at Ocean Diver is that you use a third for the ascent & exit, leaving 25% in the cylinder on exiting the water.

This is still the same theory at Sports Diver, 25% should remain on exiting the water.

33% for descent & outward leg of dive.
33% for return to shot line.
33% for ascent & safety reserve.

This should leave 25% or more in the cylinder as a reserve.

Gareth

[Mike Halligan]

All

Oh dear, we appear to have two BSAC sources giving conflicting advice?

1. The Diving Manual gives 25% of the air required for the dive as the reserve.

2. ST5 gives 33% of the air required for the dive as the reserve.

I'm going to flag this one to the appropriate NDC Group for comment.

Edward

Edward,

I don't think it is quite that bad.

"The Diving Manual" (for OD, SD level) says 25% of cylinder capacity at illustration on p64 and the same 25% or min 50 bar in text at p65.

"Safe Diving" says a minimum of 25% of cylinder's capacity (p4).

ST5 student notes say 2/3rds up to leaving the bottom, 1/3rd for ascent AND reserve (p74). They also note this will generally give 50 bar reserve at the surface.

ST5 then goes on about adding half, but this is in the context of calculating that final 1/3rd (p75). ST5 V/As are consistent with the Student Notes

We may be splitting hairs on this one. 25% of a SD's 15 litre 232 (when chilled to 220) less an ascent from 30m is not going to be very far from 50bar. The discrepancy, if there is one, should be covered in what the instructor adds in discussion of V/A content and worked examples, I guess.

Mike

[Edward]

33% for ascent & safety reserve.

This should leave 25% or more in the cylinder as a reserve.

Gareth


ST5 student notes say 2/3rds up to leaving the bottom, 1/3rd for ascent AND reserve (p74). They also note this will generally give 50 bar reserve at the surface.

ST5 then goes on about adding half, but this is in the context of calculating that final 1/3rd (p75). ST5 V/As are consistent with the Student Notes


Hi,

I think having two calculation methods based on thirds has caused some confusion (otherwise this thread wouldn't exist). If it was as simple as implied then why are we having this discussion.


I don't like it as it confuses with the original (and more widely known) rule of thirds...

Edward

[PhilB]

Hi,

I think having two calculation methods based on thirds has caused some confusion (otherwise this thread wouldn't exist). If it was as simple as implied then why are we having this discussion.




Edward

I don't think the fact that there are several methods of calculating an air reserve is the problem. ST5 specifically states that the amount to leave in reserve will vary depending on the conditions and depth of dive.

Surely a more fundamental problem is that in the theory exams (eg Sports Diver paper A question 15) we ask an exam question which requires you to use one particular method in order to get the 'right' answer. Not really fair on the student. How about amending these questions to include any assumptions that are to be used ie how much to leave in reserve and what surface air consumption rate to use.

Phil

[Dave Bewick]

I don't think the fact that there are several methods of calculating an air reserve is the problem. ST5 specifically states that the amount to leave in reserve will vary depending on the conditions and depth of dive.

Surely a more fundamental problem is that in the theory exams (eg Sports Diver paper A question 15) we ask an exam question which requires you to use one particular method in order to get the 'right' answer. Not really fair on the student. How about amending these questions to include any assumptions that are to be used ie how much to leave in reserve and what surface air consumption rate to use.

Phil

Gets my vote.

[Mark Cowgill]

Thanks all for your help I am taking the exam tonight so I will let you know how I get on with these particular questions ,I am confident on the maths of it now so fingers crossed here we go:eek: .

Mark

[Steve Walsh]

I don't think the fact that there are several methods of calculating an air reserve is the problem. ST5 specifically states that the amount to leave in reserve will vary depending on the conditions and depth of dive.

Surely a more fundamental problem is that in the theory exams (eg Sports Diver paper A question 15) we ask an exam question which requires you to use one particular method in order to get the 'right' answer. Not really fair on the student. How about amending these questions to include any assumptions that are to be used ie how much to leave in reserve and what surface air consumption rate to use.

Phil


all the figures are in the sports diver manual, rev2 jun 2004 p 73 under air required for dive subsection nervousness a safe rule of thumb is to base calculations on 25 L/m.
p72 of the same version explains the rule of thirds for SD level.

Personally I calculate on a higher rate 30L/m as if the brown tuff hits the rotating device you will increase air consumption and may need them extra few bar, if it means a shorter dive then so what at least I can get another dive in another day.

[Mark Cowgill]

Passed, :) got the questions correct on air planing thanks everyone. Just one comment though and I hope I aint speaking out of turn. I thought although the test paper was overall a good selection of relevant questions it seemed to me that some of the questions were designed to trip you up rather than test your knowledge on diving. I felt that I had done a lot of revision based on what I had been taught in the theory lessons and what it says in my sports diver student notes. I passed with a mark of 27 out of 30 which with my past exams results at school stands up pretty well but as I say it seemed as though some of the questions were how to read a question that is not clear and straight forward. then again that could be the way of Bsac finding out how you deal with situations that are not obvious.
Thanks again :D



Mark

[Dave Bewick]

Passed, :) got the questions correct on air planing thanks everyone. Just one comment though and I hope I aint speaking out of turn. I thought although the test paper was overall a good selection of relevant questions it seemed to me that some of the questions were designed to trip you up rather than test your knowledge on diving. I felt that I had done a lot of revision based on what I had been taught in the theory lessons and what it says in my sports diver student notes. I passed with a mark of 27 out of 30 which with my past exams results at school stands up pretty well but as I say it seemed as though some of the questions were how to read a question that is not clear and straight forward. then again that could be the way of Bsac finding out how you deal with situations that are not obvious.
Thanks again :D



Mark

Questions designed to trip you up are wrong. It is worth pointing any of these out through your T.O. to the area coach, or straight to HQ if you prefer. In the past we have had multiple choice questions on '88 tables where the options have been.

A. D
B. C
C. B
D. A

I kid you not. It takes a while to fine tune these things, but please do provide feedback while it is still fresh in your mind.

P.S. Well done on passing!

[Dave (Simmo)]

I work for an employer who sets exams in the same format as BSAC. Where you HAVE to read every IF, AND, OR, BUT, etc etc or you will fail the exam. The argument they use is if you know your subject matter [as you obviously did] and you read [not speed read] the question you will get the answer correct. But if you don't know your subject matter you'll fail.

the proof of the pudding as they say is in the eating.
Diving exposes us to a degree of risk, which is minimised by good training. Given the low number of diver fatalities, I’d say the exam's are well pitched to test us and readily achievable. In my club after each exam i've passed the answers have been reviewed and any wrong investigated to determine why, leading to a re-teach of misunderstood subjects.

[PeteM]

I work for an employer who sets exams in the same format as BSAC. Where you HAVE to read every IF, AND, OR, BUT, etc etc or you will fail the exam. The argument they use is if you know your subject matter [as you obviously did] and you read [not speed read] the question you will get the answer correct. But if you don't know your subject matter you'll fail.

the proof of the pudding as they say is in the eating.
Diving exposes us to a degree of risk, which is minimised by good training. Given the low number of diver fatalities, I’d say the exam's are well pitched to test us and readily achievable. In my club after each exam i've passed the answers have been reviewed and any wrong investigated to determine why, leading to a re-teach of misunderstood subjects.
The trouble is we are teaching diving not English Comprehension. If we are teaching to someone for whom English is a second language is it reasonable to put barriers in their way? What about people who are severely dyslexic?

I've had people fail the standard papers basically because they could not get through the nuances of the questions, I’ve then taken them through a paper verbally asking them for a lot more detail and they have had no problem.

[Mark Cowgill]

I work for an employer who sets exams in the same format as BSAC. Where you HAVE to read every IF, AND, OR, BUT, etc etc or you will fail the exam. The argument they use is if you know your subject matter [as you obviously did] and you read [not speed read] the question you will get the answer correct. But if you don't know your subject matter you'll fail.

the proof of the pudding as they say is in the eating.
Diving exposes us to a degree of risk, which is minimised by good training. Given the low number of diver fatalities, I’d say the exam's are well pitched to test us and readily achievable. In my club after each exam i've passed the answers have been reviewed and any wrong investigated to determine why, leading to a re-teach of misunderstood subjects.

As you say Dave going by the low number of fatalities within BSAC we must have it right. and what I was pleased about during the test was that there was a cut of point where if you failed you failed, it was 25 out of 30 the instructor even failed his own son with a result of 24 out of 30, this shows to me the good dicipline within BSAC, it must have hurt a bit that. but at least when they are buddying he will know that his buddy knows his onions.

Mark

[Dave (Simmo)]

Your giving your time to the likes of me for free, I am very grateful and intend when suitably experienced to give my time to someone else.
But nothing fits everyone, the HQ exams provide a thorough test of understanding of the subject without being any more onerous on the instructors than need be.
If exams are to simple some recall a fair percentage, multiple guess some more and scrape through without really knowing their subject matter. The majority of us, if we do our revision, take our time, read the questions pass the exams
If someone has a special need for whatever reason then as I understand it the DO can create their own tailored fit each one of which is likely to be different but they don't have to do it for everyone.

[Roz]

Edward

If you are passing things onto Working Groups, please can you pass this one on as well.

There is only one Rule of Thirds and credit for this goes to Sheck Exley. In 1977, Sheck published an outstanding booklet titled Basic Cave Diving: A Blueprint for Survival. This book briefly described and listed the reasons for known accidents that had occurred in the late 1960's and the early 1970's. He concluded the analysis with a summary of the principle causes of cave diving accidents. The book is a "classic" and still available through the NSS-CDS and the NACD.

Sheck Exley helped devise and make known to the tiny cave diving community of the early 1970's one of our most sacred rules, the rule of thirds. Always plan ahead for your exit or return with your remaining 2/3rd's gas supply. Whatever amount of gas allotted to going in can be used for any suitable purpose. Once you reach your planned turn-around gas supply, it is time to start out, without question. For example, you begin your dive with 3000 psi (210 bar). Your planned 2/3rd's out is 2000 psi (140 bar). The thirds rule was developed on the buddy concept. Once any member of the in exiting an overhead environment dive team reaches their first third, either diver should have enough gas left that both can reach the entrance sharing gas from one source. At least in theory, this gas plan should work for any "out of gas emergency'. Of course, it does not factor in stress and increased gas consumption rates. Perhaps the best reason to use the rule of thirds is that any problem in exiting an overhead environment must be solved underwater. The extra gas buys you the time to work with the delay and solve the problem.

So in other words it is a third in, a third out and the third third should be intact on the surface. The beauty of this rule is that it is simple. There doesn't need to be an Ocean Diver version, if you want to teach them rule of thirds, then a third in, a third out and the third third on the surface is the right one and the only version.

I look forward to seeing this being adopted.
- Roz

[Nigel Hewitt]

a third in, a third out and the third third on the surface is the right one and the only version.I was taught is as a third to take me in, a third to bring me out and a third to bring my buddy out but yes, this is the rule of thirds.

[Martyn Ward]

Edward a third in, a third out and the third third on the surface is the right one and the only version.

I look forward to seeing this being adopted.
- Roz

And so, presumably, do all the good folks out there who are running compressors and aren't giving discounts for "topping-up" third-full cylinders :D

(note to self: wait for it......)

[Gareth]

I fully agree. There is only one rule of thirds, unfortunately its not what we teach!

I know I said this earlier in the thread, but it remains a serious irritation. Worse still it now presents an area of confusion for the less experienced.

Gareth