BSAC Trimix

[Graham]

Hello all, nice to see the new BSAC forum off & running, long may it continue.

I have registered recently & by way of introduction I have a question.

With the advent of a BSAC Trimix course, I am curious to know other members feelings about the maximum depth limit of 50M for Dive Leaders.
Would or indeed should this be reduced for air divers?

Regards
Graham

[Steve Pearson]

I don't think it is a problem, and personally have done a lot of 50m dives on air before qualifying on Trimix.

I came up throught the old Novice diver route in the late 80's, and when I passed my sports diver was qualified to 50m, which was subsequently reduced to 35m.

Diving to 50m isn't a problem if you are confident in your equipment and abilities, and are able to effectively identify when you are narked and can manage it.

I think that even though someone may be a dive leader, it doesn't automatically make them a 50m diver. Some may not want to go down to those depths, which is entirely their choice, however those who do decide to go that deep should do it progressively, with someone more experienced who is competent at that depth, until they themselves are confident and competent.

the type of narcosis I experience is a reduction in peripheral vision, and feeling of claustrophobia. I manage it by constantly doing "what if" drills in my head, and mathematical sums. I find that it helps me to focus better on what I'm doing, and the effects of narcosis on me are then minimised to the extent that I no longer notice them. Moving onto Trimix however is fabulous from a narcosis point of view but has penalties associated with it, one being cost. For a typical trimix dive to 60m+ I would expect to pay in excess of £45, as opposed to about £10 for a 50m air dive

Steve

It is also important to ensure that when diving to those depths you have the right equipment for the job with sufficient redundancy for any incidents.

[Alan Ewart]

An interesting question. I'm not sure it needs to be reduced. With the right skill level, the right kit and the right mindset I think it's safe enough. I wonder how often any of us dive to this depth on air anyway?

[Paul Oliver]

I am quite happy diving on Air to 50m as well although i always use a bit of Nitrox even if its only EAN23. I'd only go to 50m a couple of times in a season and often not at all. I aim to do a Trimix course but the cost of the course and fills are (as Steve says) rather high, i very much doubt i would use Trimix for anything shallower than 40-45m.

There is also the fact that i may well end up with a binned dive and a fill in me twinset that was of no use for some time (although i dive off the club Rhib on me single 15 and Pony generally).

I see no reason to reduce this depth qualification, i also know a lot of DL's who have not been below 35-40m and have no interest in doing so.

As a personal view i would like to see more accessibility and understanding of the ERD Course and its emphasis on good dive planning, gas management and planned Deco.

As an aside i am rather keen to be a guinea pig on the first BSAC Trimix Course :)

[Graham]

Personally, I have done quite a few dives to 50m on air, gradually building up to that depth, not only throughout my diving career but during the diving "season".
I do feel however that (as the article in this months Dive suggests ) with other agencies & resorts around the globe reducing the maximum depth for air divers, BSAC will follow.
I believe it's just a matter of time.

[Ben Panter]

Although I've done a fair number of 50m air dives in the past, in the last few years I've not bothered. In fact, I'm not even sure of the last time I went to 40. Although properly dived up I'm sure that I could manage a dive to those depths, I don't think I would have much memory of the dive, and were a serious incident to occur I don't think I would be in a fit state to deal with it. I'd guess that this sort of logic comes to most people in the end, and they either stop diving deep or switch to mix.

Is it worth bringing the depth limit down? I don't know. For most folks I would guess it is self regulating anyway, hopefully by the time that a diver has become DL they've evolved the smarts not to rush straight down to as deep as they can go. At first glance, the incident reports don't seem to highlight it being a major cause of incidents.

The biggest hassle I can see for changing it would be the members who qualified years ago and see it as their competency being challenged. They'll be vocal and huff and puff and, worst case scenario, change their clubs over to regimes where that depth is still permitted. We don't want that.

So what's the solution? I think continual education. Encourage people to consider 50m as allowable, but too deep for air for the majority of dives.

[Andy Wade]

Although I've done a fair number of 50m air dives in the past, in the last few years I've not bothered. In fact, I'm not even sure of the last time I went to 40. Although properly dived up I'm sure that I could manage a dive to those depths, I don't think I would have much memory of the dive, and were a serious incident to occur I don't think I would be in a fit state to deal with it. I'd guess that this sort of logic comes to most people in the end, and they either stop diving deep or switch to mix.

Is it worth bringing the depth limit down? I don't know. For most folks I would guess it is self regulating anyway, hopefully by the time that a diver has become DL they've evolved the smarts not to rush straight down to as deep as they can go. At first glance, the incident reports don't seem to highlight it being a major cause of incidents.

The biggest hassle I can see for changing it would be the members who qualified years ago and see it as their competency being challenged. They'll be vocal and huff and puff and, worst case scenario, change their clubs over to regimes where that depth is still permitted. We don't want that.

So what's the solution? I think continual education. Encourage people to consider 50m as allowable, but too deep for air for the majority of dives.


Agreed.
I an an 'older' diver, I qualified years ago and have done many dives to 50m on air in the past, but I wouldn't exceed 40m on air by choice.
Headaches, disorientation, scant memories of the dives done at that depth, all these factors led me to reduce the depth limit a long time ago.
30m would be about my planned max depth nowadays.
I think it's called evolution...
Either that or self preservation. :)

I can clearly remember sitting and shivering on the bow post of the Rhondo in the Sound of Mull at 52.5 metres, watching my budding standing on the mud/silt bottom in front of me, I also clearly remember the struggle after this to ascend the first few metres up to 45m, it was quite a labour. I don't remember 'seeing' that much of the wreck at that depth though. It's all a bit of a blur really, until we could see the bridge section above us.

[Chris Cherrington]

...hopefully by the time that a diver has become DL they've evolved the smarts not to rush straight down to as deep as they can go. ....

I remember the article in Dive magazine where a newly qualified DL scared himself silly by doing just that.

There are two issues here IMO. Firstly whether the DL qualification is a depth one, which it is not. And second whether dives to 50m can be conducted with air.

For myself I think that the increased depth should come with a revised AD and include depth training. DL is about leading dives and helping other divers. We have had some big debates about AD and I think there are many others that have a similar view.

As to air - for me it stops at 40m. Under ideal conditions it can be used to greater depths but the UK rarely has ideal conditions. If there are no accidents the 50m limit will probably stay, but I think that somewhere in the future 40m will become the accepted maximum worldwide and most insurance companies will demand this.

Chris

[Mike Rowley]

With the advent of a BSAC Trimix course, I am curious to know other members feelings about the maximum depth limit of 50M for Dive Leaders.
Would or indeed should this be reduced for air divers?

Regards
Graham[/QUOTE]


Graham

The BSAC recommended depth limit for air is already 40m for rebreathers.

It is widely accepted that narcosis is a major factor in many incidents, it has been identified as such by coroners. Gas density and reslutant CO2 retention which in turn has implications for oxygen toxicity and DCI are all significant considerations as I am sure you are aware.

When BSAC has a full suite of mixed gas courses in place it is logical that the current 50m open circuit air depth recommendation must be looked at again.

The logical long term move is nitrox down to 40m and trimix from there down.

Incidently, Jeff Reed (BSAC Technical Leader) announced at DOC that the current maximum depth recommendation for mixed gas diving within the BSAC for those divers suitably qualified will be increased to 80m as from 1st January 2006.

Cheers

Mike Rowley:)
BSAC NDC Tech Development Leader

[TerryH]

Graham

The BSAC recommended depth limit for air is already 40m for rebreathers.

It is widely accepted that narcosis is a major factor in many incidents, it has been identified as such by coroners. Gas density and reslutant CO2 retention which in turn has implications for oxygen toxicity and DCI are all significant considerations as I am sure you are aware.

When BSAC has a full suite of mixed gas courses in place it is logical that the current 50m open circuit air depth recommendation must be looked at again.

The logical long term move is nitrox down to 40m and trimix from there down.

Incidently, Jeff Reed (BSAC Technical Leader) announced at DOC that the current maximum depth recommendation for mixed gas diving within the BSAC for those divers suitably qualified will be increased to 80m as from 1st January 2006.

Cheers

Mike Rowley:)
BSAC NDC Tech Development Leader




Or how apout making DL 40m with deco and AD 50m with a beefed up
Ext Range/Deep air section.

Lots of scope here for some quality rewrites to whats looked at as tired
grades :-)

T.

[Steve Pearson]

Or how apout making DL 40m with deco and AD 50m with a beefed up
Ext Range/Deep air section.

Lots of scope here for some quality rewrites to whats looked at as tired
grades :-)

T.

I agree with you on this point Terry, a reduction to 40m for DL would be a good reason for those wishing to go deeper to go for AD, or a Trimix course.

The AD qual definitely needs beefing up, and an ERD type module as part of the AD course would make sense, especially when diving to 50m, as it should really be done with twins, and preferably a deco gas as well. There is certainly a lot of scope for inclusion of a number of elements currently contained within SDC's to be incorporated into a new AD grade.

Steve

[johnkendall]

I can clearly remember sitting and shivering on the bow post of the Rhondo in the Sound of Mull at 52.5 metres, watching my budding standing on the mud/silt bottom in front of me, I also clearly remember the struggle after this to ascend the first few metres up to 45m, it was quite a labour. I don't remember 'seeing' that much of the wreck at that depth though. It's all a bit of a blur really, until we could see the bridge section above us.

You wouldn't see much of the wreck at that depth, there's virtually nothing there.

I once was told the following "You don't want to do the rondo on Mix, it's boring. It's only fun on air"

HTH
J

[Beanie]

You wouldn't see much of the wreck at that depth, there's virtually nothing there.

I once was told the following "You don't want to do the rondo on Mix, it's boring. It's only fun on air"

HTH
J

I did the rondo on mix :)

[PeteM]

I did the rondo on mix :)

And was it boring?

[Beanie]

And was it boring?
No

It was quite amusing watch the two who went to the bottom on air shoot down past us and back up again only to be still decoing when we got back to the stern :)

20/30 to 30m its the way forward :D

[Mike Rowley]

I agree with you on this point Terry, a reduction to 40m for DL would be a good reason for those wishing to go deeper to go for AD, or a Trimix course.

The AD qual definitely needs beefing up, and an ERD type module as part of the AD course would make sense, especially when diving to 50m, as it should really be done with twins, and preferably a deco gas as well. There is certainly a lot of scope for inclusion of a number of elements currently contained within SDC's to be incorporated into a new AD grade.

Steve

Steve & Terry

I have seen no evidence to suggest that Advanced divers are less suseptible to nitrogen narcosis, CO2 retention due to gas density, oxygen toxicity or DCI.
The issue surely is whether it is safer and more logical to use a lower narcotic and molecular weight gas for dives deeper than 40m, not whether to find a reason for doing Advanced Diver. The latter needs to be a qualification that stands on its own merits and attracts applicants for that reason.

Mike:confused:

[Steve Pearson]

Steve & Terry

I have seen no evidence to suggest that Advanced divers are less suseptible to nitrogen narcosis, CO2 retention due to gas density, oxygen toxicity or DCI.
The issue surely is whether it is safer and more logical to use a lower narcotic and molecular weight gas for dives deeper than 40m, not whether to find a reason for doing Advanced Diver. The latter needs to be a qualification that stands on its own merits and attracts applicants for that reason.

Mike:confused:

Mike

whilst I agree with you in a small part, O2 tox down to 50m isn't an issue as the ppO2 is only 1.26, DCI can happen irrespective of depth or gas, and CO2 retention at these depths is probably pretty negligible unless exerting yourself and shallow breathing, therefore the only real issue is Narcosis. This affects different divers in different ways and at different depths and to different degrees of impairment. Therefore what is detrimental to one diver may not be to another, and therefore each should make their own decision as to whether they are capable of handling the depth within the limits of their experience, which as I said earlier comes down to training, correct equipment and experience.

I have personally done over 12 dives to 50m this year on air, and over 30 greater than 40m and did not have a problem with doing so, however I agree that doing it with a mix gives much better clarity and reduces sensual impairment, but at a cost, and that cost may be outside the budget of some divers.

It is not a reason on it's own to go for advanced diver, but the qual should reflect the level of training, after all, one of the reasons some people go for DL is not so they can lead a dive, they can do that quite adequately as SD, they go for it so as to be insured down to 50m for deeper dives.

Looking at the incident stats it doesn't appear that there are many incidents in the 41-50m range, with the majority being in the 21-30m range. This is the same for the depths at which the incidents started, so is diving to 50m on air really as big an issue as you seem to make out.

I hope that the depth isn't reduced just so that Trimix can be pushed at a cost to the masses.

Steve

[Janos]

The AD qual definitely needs beefing up, and an ERD type module as part of the AD course would make sense, especially when diving to 50m, as it should really be done with twins, and preferably a deco gas as well. There is certainly a lot of scope for inclusion of a number of elements currently contained within SDC's to be incorporated into a new AD grade.

I don't think AD such be a deep diving qualification.

Janos

[Steve Pearson]

I don't think AD such be a deep diving qualification.

Janos

You're missing the point. The max depth for DL/AD is 50m, the question is should this depth limit be reduced to 40m, I'm saying NO!, and if they do reduce it, do it for DL only and keep AD at 50m, but introduce some advanced training to cover ERD practices for safely going to that depth. It isn't saying that all AD's should and would go to that depth, but if we start reducing it, the insurance cover will be removed for depths below the new depth of 40m, and therefore it would preclude everyone diving to those depths unless they've done a Trimix course, and want to pay £50/dive just to go there.

Leave it alone, get the Trimix course introduced instead of just talking about it, and educate people that they really should be diving to those depths using mixed gases for a better dive.

Steve

[TerryH]

Steve & Terry

I have seen no evidence to suggest that Advanced divers are less suseptible to nitrogen narcosis, CO2 retention due to gas density, oxygen toxicity or DCI.
The issue surely is whether it is safer and more logical to use a lower narcotic and molecular weight gas for dives deeper than 40m, not whether to find a reason for doing Advanced Diver. The latter needs to be a qualification that stands on its own merits and attracts applicants for that reason.

Mike:confused:


BSAC currenty allow 50m on air once progression is done during Dive Leader.
Trouble is that although talked about there is no actual requirement or
training that includes any redundant systems such as twins. That topic only
gets taught physically in the Advanced Nitrox course.

Yet between 35-40m we will be edging or going into minor deco, deeper and
its major deco.

There is a very defined line here between what is a safe intermediate
dive and what is a deeper more advanced dive. No matter what benefits
we have doing Trimix, there are many of us who wont be spending
dosh just to do the odd deeper dive.

So why not make Advanced into a true advanced grade and inclusive
of all the elements to manage a 50m air dive?

Its not about depth. Its about filling in all the gaps in the present
syllabus that allow such depth, but doesnt go over any of the techniques
to do it. Big difference.

TerryH

[Mike Rowley]

Mike

whilst I agree with you in a small part, O2 tox down to 50m isn't an issue as the ppO2 is only 1.26, DCI can happen irrespective of depth or gas, and CO2 retention at these depths is probably pretty negligible unless exerting yourself and shallow breathing, therefore the only real issue is Narcosis.

It is not a reason on it's own to go for advanced diver, but the qual should reflect the level of training, after all, one of the reasons some people go for DL is not so they can lead a dive, they can do that quite adequately as SD, they go for it so as to be insured down to 50m for deeper dives.

Looking at the incident stats it doesn't appear that there are many incidents in the 41-50m range, with the majority being in the 21-30m range. This is the same for the depths at which the incidents started, so is diving to 50m on air really as big an issue as you seem to make out.

I hope that the depth isn't reduced just so that Trimix can be pushed at a cost to the masses.

Steve


Steve

PO2 is, as you say 1.26 bar at 50m. However, the work of breathing is greater at 6.0 bar absolute than at 5.0 bar absolute due to density of gas. CO2 retension has always been an issue, even with open circuit diving. There is some evidence that if a diver is breathing a gas PO2 > 0.8 bar then there is less likelyhood of CO2 symptoms presenting until the diver starts to black out. On this basis many of us may be experiencing levels of CO2 retension during deeper air dives and be completely unaware of it.

I have witnessed several incidents, one of which resulted in the casualty blacking out a number of times underwater. He was saved by his buddy carrying out a CBL from 50m. Many more divers regularly surface complaining of headaches. Now, you can put this down to sub-clinical DCS or CO2 retension. CO2 does not show up on post mortems as far as I know, although I would defer to more knowlegible people on this. The fact remains that the two conditions are often related. Many of us unintensionaly skip breathe even when on open circuit and CO2 retension is an inescapeapable fact when you begin to work a bit harder. The denser your gas the more significant this becomes. Extremely small PCO2 values lead to problems.

CO2 is a vasodilator and leads to increased physical exercise in itself. This mitigates towards oxygen toxicity, narcosis and DCI. If a lighter, less narcotic gas is used then CO2 retension is reduced and the propensity to the others similarly reduced.

There seems to be a consensus forming within most diving agencies that 40m is the logical safe diving limit for air and nitrox is a safer gas for these depths anyway. My personal view is that this is the correct way to go given the wealth of evidence supporting it.

Your point about the majority of incidents occuring in the 20 - 30m depth range is again correct. However, a more detailed analysis reveals that a significant number of serious underwater incidents happen during deeper dives. Looking at 2004 fatalities 41.6% happened on dives >30m and 25% on dives > 40m. These tend to be the depths where narcosis and possible CO2 retension may begin to become issues.

The extension to 50m at Dive Leader did not arrive as a result of the Dive Leader sylabus being designed to give people the skills to cope with extra depth. In fact there is little in Dive Leader that addresses this issue, either theoreticaly or practicaly. It was actually a reduction of depth for Sport Divers to 35m as I remeber, largely driven by external pressures. This seems to me to have been an effect of the "law of unintended consequencies" that people often see DL as a passport to 50m depth. Currently DL and AD have more to do with leading and organising diving rather than extending depth capabilities, ERD is where we really begin to get to grips with this.

The question is where does recreational diving end and technical diving begin?

Trimix cost is an issue. It is not necessary to run particularly rich mixes for dives in the 40 - 50m range, 21/30 is adequate for this but I do agree it is more expensive. Of course, on a rebreather its very cheap and flexible to run trimix diluent all the time. Sorry about that, couldn't resist the plug.:D :D :D

Having said all of that, the issue is not likely to rear its head any time soon and by the time it does you may well be one of the people making the decisions, me having been retired to more sedentary pastimes.:D

Cheers

Mike

[Steve Pearson]

Hi Mike,

I had to play a bit of devils advocate, and am trying to protect the current depth issue with regards to insurance.

I am in total agreement with you that diving below 40m is better on a mix, and feel that once the Trimix course has been introduced, at an affordable cost for everyone, then the majority will use it for deeper dives, without the need to reduce maximum depths.

It's just about educating people as to what's best for them.

Steve:)

[Graham]

You're missing the point. The max depth for DL/AD is 50m, the question is should this depth limit be reduced to 40m, I'm saying NO!, and if they do reduce it, do it for DL only and keep AD at 50m, but introduce some advanced training to cover ERD practices for safely going to that depth. It isn't saying that all AD's should and would go to that depth, but if we start reducing it, the insurance cover will be removed for depths below the new depth of 40m, and therefore it would preclude everyone diving to those depths unless they've done a Trimix course, and want to pay £50/dive just to go there.

Leave it alone, get the Trimix course introduced instead of just talking about it, and educate people that they really should be diving to those depths using mixed gases for a better dive.

Steve

In my own mind (pocket also) I am generally in agreement with Steve on this one, but I still feel that external inflences will push BSAC to revise the depth limit for air, both for DL & AD. I just don't think the arguments for air to 50m will stack up with the actuaries for much longer.
I must admit though, Ive not yet had chance to study the incident reports for depth related problems.

I also think that the AD course is a little "light" & would benefit from some Extended Range Training. :)

Graham

[MattS]

I guess what annoys me about this is that whenever an absolute LIMIT or RULE is imposed it infers that BSAC divers are incapable of understanding the risks and must be told what to do. I unreservedly disagree with that notion.

Statistics and damn statistics. We thankfully don't have enough fatalities to start making meaningful conclusions. Even if gas mix was stated in the incident reports it would not really mean anything. The risk of serious injury or fatality rises exponentially with depth. We know that. We have known it for years.

Using a CCR to make 40m to 50m He dives compared to similar dives on OC air is quite an interesting conundrum in terms of risk! The complexity of a CCR provides wider scope for equipment failure and human error. The Air diver has to cope with the influence of narcs but his kit is simple to use and far more reliable.

Diving can be unforgiving, deep diving particularly so. That really is about the only safe conclusion you can make. Deep diving is not for everyone, deep air is not for everyone, CCRs are not for everyone. Accept it all or ban it all because there seems to be absolutely no firm evidence that one approach is any safer than another.

Perhaps the lack of statistics and BSACs excellent safety record needs mentioning to these actuaries from time to time.

Just my 2p



BTW Steve, if you know nothing else about CO2, just know to avoid it. You should have been taught that during ERD training. Like narcosis CO2 makes pretty much everything worse.

[ray]

Hi.

Mix 21 / 45, set point 1.3, Mod 52 metres, END 22 metres, 3 Lr Dil bottle filled with 21 /45 £ 7.50 , easy 2 dives on it. Get yourself a YBOD , plus you will be able to see the tat as you swim by :D

[Graham]

Hi.

Mix 21 / 45, set point 1.3, Mod 52 metres, END 22 metres, 3 Lr Dil bottle filled with 21 /45 £ 7.50 , easy 2 dives on it. Get yourself a YBOD , plus you will be able to see the tat as you swim by :D

Hmmmm now there's a thought. How can I get a go of one of them in the North West. :D

[Steve Pearson]

There are some rebreather try dives going on at Robin Hood Watersports, Heckmondwyke (I thinks that's how it's spelt)

Gary Wyke is organising it

PM me for details

Steve

[Chris Cherrington]

You're missing the point. The max depth for DL/AD is 50m, the question is should this depth limit be reduced to 40m, I'm saying NO!, and if they do reduce it, do it for DL only and keep AD at 50m, but introduce some advanced training to cover ERD practices for safely going to that depth. It isn't saying that all AD's should and would go to that depth, but if we start reducing it, the insurance cover will be removed for depths below the new depth of 40m, and therefore it would preclude everyone diving to those depths unless they've done a Trimix course, and want to pay £50/dive just to go there.

Leave it alone, get the Trimix course introduced instead of just talking about it, and educate people that they really should be diving to those depths using mixed gases for a better dive.

Steve

Steve, I agree that the way to handle this is to increase the depth at AD and include some training as per Terry's post. Of course this is easy for us to say but involves lots of work for BSAC HQ!!

However, I just want to pick up one point of your post and that's gas cost.

The last normoxic I bought in the UK was £23 for twin tens (21/30) and this cost could be reduced by blending with the branch compressor.

There is a perception that mix is expensive. I hope very much that the introduction of a mix ticket by BSAC will make many people look at this gas in a new light and help drive down the costs. Not all branches will want to take advantage but I hope enough will that this makes a big change to BSAC and the membership profile.

I think Mike et al are to be congradulated for this development - lets hope it lives up to expectation.

Chris

[garethwoodruff]

I've heard rumours of a skill development course aimed at Sports divers (experienced I hope), which will allow them to dive to 50 meters....

Now if this covers redundant air systems, gas shutdowns, effectively a version of the extended range course this might be the answer. I don't think its really covered until you get to extended range level diving, but to me diving on air in the 40 meter range is very much extended range type diving.

Why not look again at that and if as a sports diver you pass, you can dive to 50 meters, now theres a thought! Not sure we have the instructor base with this sort of expereince to do this justice, but just a thought

[Janos]

You're missing the point. The max depth for DL/AD is 50m, the question is should this depth limit be reduced to 40m, I'm saying NO!, and if they do reduce it, do it for DL only and keep AD at 50m, but introduce some advanced training to cover ERD practices for safely going to that depth. It isn't saying that all AD's should and would go to that depth, but if we start reducing it, the insurance cover will be removed for depths below the new depth of 40m, and therefore it would preclude everyone diving to those depths unless they've done a Trimix course, and want to pay £50/dive just to go there.

Leave it alone, get the Trimix course introduced instead of just talking about it, and educate people that they really should be diving to those depths using mixed gases for a better dive.

Steve

Sorry, I misunderstood you. I thought you were suggesting that ERD be part of Advanced Diver.

Janos

[Steve Pearson]

Steve, I agree that the way to handle this is to increase the depth at AD and include some training as per Terry's post. Of course this is easy for us to say but involves lots of work for BSAC HQ!!

Hi Chris,

This shouldn't be very much work as the depth is already 50m for AD, it's only a matter of amending the AD syllabus to include some ERD training.


However, I just want to pick up one point of your post and that's gas cost.

The last normoxic I bought in the UK was £23 for twin tens (21/30) and this cost could be reduced by blending with the branch compressor.

There is a perception that mix is expensive. I hope very much that the introduction of a mix ticket by BSAC will make many people look at this gas in a new light and help drive down the costs. Not all branches will want to take advantage but I hope enough will that this makes a big change to BSAC and the membership profile.

When I was referring to costs of £40 - £50, that was using twin 12's and with an optimum 23/33 mix, using a 50% deco mix in a 7L, depending upon availability in your area I would expect to pay approx £40. Branches with a compressor are in a minority. The costs of Helium have increased recently resulting in additional costs for the mix.

Compare this with the typical cost of a gas fill on twin 12's - approx £6 there is a big difference. Also the mix is usually pretty specific per dive, and unless you intend diving in a quarry to this depth (which there aren't that many) there's always a possibility of you getting blown off, and therefore may not have the opportunity of getting your next dive suitable for that mix.

Cost isn't an issue for me, but may be for some people, what is the issue is insurance, and insurance companies invalidating a claim if someone touched 41m on a dive if the limit for air has been reduced to 40m, and they had an incident.

Steve

[Mike Rowley]

I guess what annoys me about this is that whenever an absolute LIMIT or RULE is imposed it infers that BSAC divers are incapable of understanding the risks and must be told what to do. I unreservedly disagree with that notion:)

I would agree with you Matt. I don't think you will find anyone in the NDC Tech group who would dissagree.

However, that said we do have to make recommendations in BSAC Safe Diving Practices since this forms part of our risk assessment guidence. I stress the word "recommendation". I don't want to revive this old chestnut but I would just point out that someone diving slightly outside the SDPs does not automatically invalidate BSAC third part insurance. As I understand it, the test would be whether the transgretion played any significant part in a claim. For instance, if someone were decompressing on PO2 of 1.6 bar and was hit by a boat prop then the fact that they were outside the BSAC recommendations on PO2 would have no bearing on the incident therefore it would not effect the third party insurance. I can't imagine what sort of third party claim would arise out of this though, perhaps the boat owner might claim for damage to his prop.:D

By the time we have to reconsider the issue of air depth recommendation the descisions may have already been made for us by a combination of education, external pressures and general practice.

Cheers

Mike:)

[Chris Cherrington]

... Branches with a compressor are in a minority.

....Cost isn't an issue for me, but may be for some people, what is the issue is insurance, and insurance companies invalidating a claim if someone touched 41m on a dive if the limit for air has been reduced to 40m, and they had an incident.

..

On the first point that's something we should change!!! Having access to a compressor is a big plus point for me. I wouldn't join a club that didn't have one...

On the second I agree totally. I guess that insurance, rather than any "rules" or recommendations will sound the death bell for air below 40m eventually.:(

Chris

[MattS]

I hope very much that the introduction of a mix ticket by BSAC will make many people look at this gas in a new light and help drive down the costs.How is greater use going to drive down the cost? Helium is a finite resource. The faster it is used up the faster the cost will go up.

[Chris Cherrington]

How is greater use going to drive down the cost? Helium is a finite resource. The faster it is used up the faster the cost will go up.

Oil is a far more finite resource. However, I meant that the BSAC mix ticket should be a bit cheaper than the TDI/IANTD tickets and that would help. Diver's use of He is negligable compared to industry.

Chris

[MattS]

Oil is a far more finite resource.Despite the economy of scale that ubiquitous reliance on oil affords, it is rather more expensive than Helium per litre. Thankfully I can do quite a few useful trips on £30 quids worth of DERV.
However, I meant that the BSAC mix ticket should be a bit cheaper than the TDI/IANTD tickets and that would help.Is training at this level really governed by the cost of the course? The most common advice, and that with which I personally agree, is that the instructor is far more important than the particulars of the ticket.

You may want to consider the history we already have from the technical agencies. The number of Trimix courses run is far higher than the number of Trimix dives taking place warrants. Perhaps the majority of people taking Trimix courses subsequently realise they lack either the commitment or funds needed to dive Trimix regularly. Others see Trimix qualification (mistakenly) as the pinnacle of diver achievement. Whichever, it is a remarkably small number that actually use the gas in pursuit of underwater objectives.

The VAST majority of dives in the 40 to 50m range are currently performed on Air. The vast majority are performed incident free. Increased adoption of CCRs is increasing the number of Trimix dives taking place but that fact has not exactly come without cost in terms of diving incidents. Personally I think there is a lot to be said for promoting BSACs current deep diving guidelines rather than just another gas.
Diver's use of He is negligable compared to industry.Industry re-charges the cost...as do Trimix course instructors.

[John Williams]

For instance, if someone were decompressing on PO2 of 1.6 bar and was hit by a boat prop then the fact that they were outside the BSAC recommendations on PO2 would have no bearing on the incident therefore it would not effect the third party insurance. I can't imagine what sort of third party claim would arise out of this though, perhaps the boat owner might claim for damage to his prop.:D

Mike:)

:eek: Perhaps the insurance company might have something to say about doing deco stops in a place where a boat that has a prop that reaches deco stop depths might be passing?

(and ppO2 of 1.6bar would be 100% at 6m! or 80 % at 10m)

Who's got a rib with a prop that goes down 6-10m?
(Any boat with a prop at these depths aint even gonna notice when a diver "fouls" the prop!...unless it's a mini sub!)

John
(but I do grasp the concept to which you allude Mike:D )

[Janos]

:eek: Perhaps the insurance company might have something to say about doing deco stops in a place where a boat that has a prop that reaches deco stop depths might be passing?

(and ppO2 of 1.6bar would be 100% at 6m! or 80 % at 10m)

Who's got a rib with a prop that goes down 6-10m?
(Any boat with a prop at these depths aint even gonna notice when a diver "fouls" the prop!...unless it's a mini sub!)

As ever, the BSAC Incident Report is a good source of information and well worth a read.


August 2005 05/212
A number of divers were ascending a shotline from a dive to 27m when a large tug was seen to be heading directly for the site. The skipper of the dive boat attempted to divert the approaching vessel by steering towards it and by radio calls. The vessel did not respond and passed directly over the shot buoy at high speed. One of the divers was pulled upwards and hit by the hull of the tug several times. She managed to get to the surface after the incident and was recovered into her boat. She was in pain and parts of her diving equipment had been damaged or lost. The pillar valve of her cylinder was bent over and leaking. The Coastguard was alerted and the other divers recalled. The boat headed back to the shore and was met by a lifeboat. The casualty was taken ashore by the lifeboat and from there to hospital. She was treated for three broken ribs, bruising to her lung, injuries to her arm and facial cuts.


Janos

[Andy Wade]

As ever, the BSAC Incident Report is a good source of information and well worth a read.



Janos

What a frightening incident.
This reminds me of an RYA Navigation course I did a few years ago. Our Instructor told us:
Rights of way are defined in the 'Rules of the Road' book, based on the international regulations for preventing collisions at sea.
He also added that basically if you're a small boat with a 'right of way' over a much bigger vessel, it would always be prudent to ensure that you don't get sunk whilst defending this 'right of way'.
He also added that you might send up flares and scream at the radio to attract their attention, then just as you veer off to try and avoid the inevitable collision, you see a bloke coming on to the bridge with a fresh cup of tea in his hand and a :eek: look on his face as he spots you and turns off the autonav.

[MattS]

He also added that basically if you're a small boat with a 'right of way' over a much bigger vessel, it would always be prudent to ensure that you don't get sunk whilst defending this 'right of way'.Ahh yes. You remind me of a line I used often while working as a despatch rider.
"It matters not a jot who's fault it was when you are the one in the Hospital bed"
Avoidance is better than cure IMVHO.

[Chris Cherrington]

Is training at this level really governed by the cost of the course?

I honestly don't know. However, enough people post up on all the various fora about the "£400 for the ticket" and "£50 for gas" as if this were an excuse to push air beyond its limits.

If cost is an issue to some people then a BSAC Tx course may help.

Personally I think there is a lot to be said for promoting BSACs current deep diving guidelines rather than just another gas.

Even BSAC stop air diving at 50m. To dive beyond that requires trimix. I don't see this development as just promoting another gas.

Chris

PS 30 quids worth of diesel only just gets me to the sea (and thats at €0.85/litre)....... jealous!!! :(

[Mike Halligan]

Rule 2 - there is no right of way, save that given by one ship altering course or speed for another.

[Alan Taylor]

XXX EDIT: Moderator messed up, apologies. Recovery of post impossible, please edit this text Alan! XXX

[Graham]

With the advent of a BSAC Trimix course, I am curious to know other members feelings about the maximum depth limit of 50M for Dive Leaders.
Would or indeed should this be reduced for air divers?


Many thanks for all the responses.
Formulating a consensus on this, it seems that the many can see a 40m depth limit for air looming, but may not be too receptive.
BSAC's current guidlines seem adequate for diving to 50m, by qualifying the depth limit with experience & gradual build up.#

I am of the opinion that a BSAC TX course is overdue & can only enhance the current training syllabus. I don't see it as just pushing another gas, but as a further tool to enhance your diving & safety.

Graham