Dive computers and BSAC88

[Alan Prior]

Personally I have a preference for Suunto dive computers and at present dive with a Gekko. When you guys are diving on BSAC88 tables do you use a dive computer with deco capability or do you just use the computer in guage mode?

[paul_c]

personal choice

and it depends on what i am doing.

20% helium i do a tabled dive with a planner.
nnitrox or air its just on the comp in deco mode

[OneDragons]

Used to dive tables and use a watch and depth gauge.

Now use Suunto in normal mode with another one as a backup. If that goes wrong, then Ill use a table.

[Richard Whitcombe]

People are insane enough to still dive the BSAC 88s for decompression diving?!

[Ian@1904]

People are insane enough to still dive the BSAC 88s for decompression diving?!
The 88 tables are aggressive when compared more recent conclusions on ascent rates. So no I don't use 88 tables for planning deco dives. There are some excellent software planning tools out there, which provide flexibility when an actual gas mix may differ from the ideal mix.

Most people are going to purchase a dive computer as watches are of little use in the water. I use a Suunto Vytec myself-usually in nitrox mode, and gauge mode for trimix dives.

[Twinsetmad]

There was a rumour a year or so ago, BSAC were working towards a new set of tables..... these are over 20 years old now, decompression theory and understanding has moved a long way in the last 20 years.... has anyone heard anything..?:)

[GaryC]

I like the 88 tables for teaching deco and getting new people into a mandatory decompression dive that is essentially not a deco dive on the computer.

Gary

[Richard Whitcombe]

As a teaching tool they're great to show decompression theory and simple to use to illustrate concepts *in a classroom*. Far easier than other format tables.

But there isnt a chance in hell id ever do a decompression dive on them. Aggressive to the point of terrifying on some profiles. Dont think ive ever met someone that actually does mandatory deco dives on them either.

[DarrenA]

I would echo what others have said...88 tables are too aggressive and multiple dives are practically impossible.

I use Sunnto computers (Helo2 and Vyper for backup) and "cut" the tables using the Sunnto Dive Planner which mirrors the dive computers very closely.

I then write the dive plan on my slate, write the backup plan on the slate and then dive.

I dive the slate.

Only if I cut the dive short would I then look to the computer to see if that is telling me I can get out of the water earlier. Only then.

If non-deco diving, I dive the computer.

[Richard Whitcombe]

VPM or Buhlmann and a slate. Computers in gauge mode for me.

No way id use the suunto model either :)

For normal single tank no-stop dives its just computers as normal.

There is no dive id actually be prepared to do on the 88s.

[Richard Whitcombe]

VPM or Buhlmann and a slate. Computers in gauge mode for me.

No way id use the suunto model either :)

For normal single tank no-stop dives its just computers as normal.

There is no dive id actually be prepared to do on the 88s.

[neil_richardson]

PROVIDING you know the logic, and PROVIDING you understand EXACTLY the theory and how the tables were put together, than you realise the tables are actually not that aggressive, and are on par with pretty much every other dive table. On many instances, actually safer, especially on the 2nd dive.....

However, nope i do not use them for dive planning, as im a devote Haldane'ite.... so typically run Buhlmans B 20/70... but factor in the haldanite findings.....

HOWEVER, for complete emergency, i have got the tables in my wet notes....

[Gareth]

As a teaching tool they're great to show decompression theory and simple to use to illustrate concepts *in a classroom*. Far easier than other format tables.

But there isnt a chance in hell id ever do a decompression dive on them. Aggressive to the point of terrifying on some profiles. Dont think ive ever met someone that actually does mandatory deco dives on them either.

I am certain back in the day, that diving used to be more agressive (in terms of decompression).

In the very early 90's my first two seasons were on 88's, & that included 50m dives. But then we only did two dives a day.

After that I bought a computer, & I started using the computer profile.
All the early diving was on air. I didn't graduate to Nitrox until 96, & that was after a season of dives with 30-40minutes of deco stops (on air).
We only used Nitrox 50 as a decompression gas, using an air profile. Partly because it was difficult to source Nitrox, partly because we didn't know what we where diving until the day, so all dives were air (back gas) Nitrox 50 for decompression (3l cylinder).
Carrying Nitrox on to a boat was often frowned upon, or immediately resulted in you being banned.
Using Nitrox or worse still Helium put you in the insane & dangerous nutter group.

Some of the comments you get from those that have experienced easy access to Nitrox & Helium amuse me no end.

I also have a long enough memory to remember all the new 'super' decompression theories & how they where super safe with the added benefit of getting you out of the water super quick. Interesting how they moved from version A to version B, version C....
Funnily enough, old Haladyn, seemed to get most things right. Despite all the new theories & tables, Buhlmann tables [1] see to be pretty 'in touch' with most of the modern variations

Even modern computers are far more conservative to the earlier ones. Just compare a Monitor II with any of the new generation!

That said, the benefits of using Nitrox or Trimix are fantastic.
Including reducing DCI risk, reduced sub-clinical DCI, better likelyhood of a full recovery if you are unfortunate to suffer DCI, & reduced Narcosis.

Gareth

[1] Yes I realise there are a number of versions / G/F

[Richard Whitcombe]

PROVIDING you know the logic, and PROVIDING you understand EXACTLY the theory and how the tables were put together, than you realise the tables are actually not that aggressive, and are on par with pretty much every other dive table. On many instances, actually safer, especially on the 2nd dive.....

Quite simply, no they're not. Compared to modern theory, modern approaches they're exceedingly aggressive. Yes they maybe on par with traditional buhlmann or US navy but nobody actually uses those. Hence gradident factors, deep stops and so on.

Quite simply, the 88s out of the book are extremely aggressive and i cant imagine anyone actually diving them.

We only used Nitrox 50 as a decompression gas, using an air profile. Partly because it was difficult to source Nitrox, partly because we didn't know what we where diving until the day, so all dives were air (back gas) Nitrox 50 for decompression (3l cylinder).
Carrying Nitrox on to a boat was often frowned upon, or immediately resulted in you being banned.
Using Nitrox or worse still Helium put you in the insane & dangerous nutter group.

Sadly a lot of dinosaurs remain in some clubs that still have the nitrox is devil gas attitude. Air and Air deco maybe 50% if you're a renegade. A 15l and 3l pony is perfectly good for 50m diving. Wings will kill you.
Ive heard that very recently from certain people who still teach new divers those idea.

Then again i do remember having someone that recently stood for NDO telling me my wing would push me face down on the surface and drown me then proceeded to try to "prove" it without success in the pool.

[ChristianG]

Quite simply, no they're not. Compared to modern theory, modern approaches they're exceedingly aggressive. Yes they maybe on par with traditional buhlmann or US navy but nobody actually uses those. Hence gradident factors, deep stops and so on.
I guess I was one of the first to get the '88 tables here in Oz. A friend sent them to me, about '90 IIRC. At that time I was exceedingly distrustful of those newfangled computers, in fact I remained so for about the next decade.

So, for that time period I used those "so dangerous" BSAC tables together with the DCIEM tables of which I have the full set - all the way to 72 metres. Before that I mostly used the US Navy table ('58 ones was it?) and the old BSAC tables. Touch wood, to my knowledge I have yet to get bent.

But lets reflect on those old US Navy tables and the BSAC '88s, two of the most commonly used tables of their day. I get just a little exasperated when people, today, say that they were dangerous, or aggressive, or stupid, or whatever. The fact of the matter is that when they came out they were nothing of the sort and the pertinent point here is those four words when they came out. Yes, it could be construed that they were aggressive, or whatever, by today's standards but so were the original computers (anyone remember the original "cockroach" computers for example?). There is absolutely no point, or reason for that matter, in comparing the standards of decompression of that day with what is today's standard, it (a) doesn't work and (b) is completely illogical. I dare say that in twenty years time we will consider today's standards as quaint and obsolete, just a long as we don't at that time describe them as stupid in some way. They're the best that, today, we've got.

[Richard Whitcombe]

They're the best that, today, we've got.

Exactly, so use the best we've got with the best current knowledge can give you. Not the best 22 years ago had despite current theory showing it to be far from ideal.

[MattS]

Quite simply, no they're not. Compared to modern theory, modern approaches they're exceedingly aggressive.I think you are overstating the case.

The BSAC 88s are basically a dissolved gas model. They are similar to every other dissolved gas model. All the dissolved models are not that much different from the original JS Haldane tables of 100 years ago. Basically Haldane made the innovative step and for the next 90 years people were just refining it.

What the 88s and all the other dissolved gas models lacked was the notion of free gas (bubbles). That was a further innovation, made possible by the development of portable Doppler monitors which were then applied to divers in (IIRC) the 1970s. Despite the technology being around for 40 years, it is still a subject which stirs much controversy amongst physiologists and decompression scientists.

In fact the 88s made some allowances for free phase, reducing the ascent rate from 18m/min to 15m/min _or_less_ and 1m/min from 6m. Further, off gassing rates are slower than on gassing, effectively increasing surface interval times. Hence the 88s are less flexible and could be said to be less aggressive than some other mainstream tables, the RDP for instance.

But let's not let detail get in the way of an extreme opinion!

True, there are some areas of the 88s that are troublesome in view of free gas being present and the trend toward longer bottom times. 15m/min probably is a bit quick. Ascending straight to 9m probably is a bit stressful. The inwater stop times probably are a little short. This is a long way from overtly dangerous though.

When my stop times on 30m+ dives started getting closer to the end of the 88s table than the start, I sometimes finished the day feeling a bit crap. Not the aches, pains, pins and needles, rashes, blurred vision or anything else that I would associate with an overt bend, just a bit too tired. So over a period of years I started using Nitrox, introduced Pyle Stops and eventually switched to higher FO2 decompression gas (circa 1999). Which seems to work fine for me and the diving I want to do - 30 mins to 1 Hour bottom time, 30m to 50m, Air + 80%. I also switched to using a computer that deals with that and carrying wet Buhlmann's for backup.

I still use the 88s for diving to 25m and they are a damn site easier to use than my computer or my Buhlmann tables.

Pick your decompression strategy to match your dive and your body. The biggest variable always turns out to be the Human body. In the scheme of things the difference the flavour of table might make is so small as to be unmeasurable. From what can be measured it turns out the safest thing to do is hydrate properly and spend less time at less depth.

Wings will kill you. Ive heard that very recently from certain people who still teach new divers those idea.Did they say _will_ kill you or _can_ kill you. The first is a myth born of holding an extreme view, the second is factual if not usual.

[Woz]

There was a rumour a year or so ago, BSAC were working towards a new set of tables..... these are over 20 years old now, decompression theory and understanding has moved a long way in the last 20 years.... has anyone heard anything..?:)88's use an algorithm that's more modern than virtually all recreational dive computers.

Problem is that no one will fund research into it as there is no commercial interest.

Gradient Factors are a Buhlmann bodge, VPM has bent lots of people in the early days. The new Uwatec computers with the heart rate thing use an unfinished theory Bertie was developing when he died. Pyle stops were made up by a man in distressing board shorts.

Trimix recreational diving is basically one great big experiment. No-one really knows what's happening!

[Richard Whitcombe]

Did they say _will_ kill you or _can_ kill you. The first is a myth born of holding an extreme view, the second is factual if not usual.


I had a WILL on a few occasions.