DSMB inflate in cold water - purging

On Wed, 28 Jan 2004 11:39:07 +0000, matts wrote:

> AA> A self inflating is much faster, and reliably much faster. The only
> AA> down side its that its bulkier than an non-self inflating bag and I can
> AA> live with that.
>
> Do you use a slob knob Al?

Slob knobs break. They are less reliable. No comparison. You can always
manually inflate a DSMBi.

Jason

--
See http://www.scuba-addict.co.uk/ to view UK dive spaces or add your own.

I> The main objective of my dive planning is to arrive at a maximised time
I> at the target depth.

It is a subtle difference but the main objective of my dive plan is to get
me back to the surface safely having achieved whatever it is I was aiming to
achieve. My main priority is to stay inside the planned envelope. Getting
as close as possible to the edges is less important and certainly I like to
be conservative about what I can and cannot achieve. In many cases the
objective is simply to go have a look at a wreck.

I> Planning a 20 minute bottom time but planning to leave the bottom at 18
I> minutes to accommodate a DSMB deployment sounds a bit odd to me.

I don't plan to leave the bottom at 18 minutes. I plan to have left the
bottom by 20 minutes.

I> If you are able to plan a 20 min bottom time then surely the plan is to
leave
I> the bottom at 20 mins, and not at 18?

At 18 mins, I prepare to leave bottom. Between 18 and 20 mins I am
deploying the bag and by 20 mins I am into the ascent. Exactly what happens
when during the two minutes is variable dive to dive. Maybe you think that
is too conservative, personally I don't care if I miss a few seconds (in
practical terms that is what it comes down to). If bottom time is that big
a deal I can play games making profiles more aggressive, but obviously that
entails increasing risks so it has to be worth it.

I> Or do you plan a 22 minute time to accommodate the deployment a sit out
I> the extra deco?

If I want 22 minutes and have the equipment then I sit out the deco. Deco
is just something you have to do, my only real concern is having enough gas.
As it is 20 mins at 70m is about the limit of my kit.

I> On a 70m dive (as quoted earlier) do you really bag-off
I> at 60m?

The context of the earlier quote was, being prepared to bag off at 60m if
you are already over time at 70m.

In normal circumstances deeper than about 30m I deploy in midwater and fin
up gently while the bag makes it's way to the surface. Generally this puts
me around 5 to 15m into the ascent before I start reeling in. I would in
fact prefer to come up a shot line from 70m but I have not always had the
choice.

Considering the turn of this thread I just want to point out that I am not
intending to make myself out as any sort of authority on 70m trimix diving.
It is at the limit of my experience as well as my kit. The bulk of my
diving is 30m to 50m. The occassions I have ventured into the 50 to 70m
range I used the same techniques for planning and DSMB deployment.

Regards
MattS

On Wed, 28 Jan 2004 11:39:07 -0000, "matts" <matts@nospam.org> wrote:

>
> AA> A self inflating is much faster, and reliably much faster. The only
> AA> down side its that its bulkier than an non-self inflating bag and I can
> AA> live with that.
>
>Do you use a slob knob Al?
>
>
He doesn't need one, he uses an inverted set.

Pete S.

matts wrote:
> Jason Poynting wrote:
> > matts wrote:
> > > Alasdair Alan wrote:
> > > > A self inflating is much faster, and reliably much faster. The
> > > > only down side its that its bulkier than an non-self inflating bag
> > > > and I can live with that.
> > >
> > > Do you use a slob knob Al?

You're trying to compare self inflating bags to slob knobs? You're kidding
right?

> > Slob knobs break. They are less reliable. No comparison. You can always
> > manually inflate a DSMBi.
>
> Is that your opinion, Al's opinion or the Inquisition's opinion?

It's certainly my opinion, I'm sure its Jason's opinion.

I haven't met the Inquisition, after all their main weapon is suprise and
fear. Sorry, their two main weapons are suprise, fear and ruthless
dedication to the Pope. No, their three main weapons are...

Al.

??>>>>> A self inflating is much faster, and reliably much faster. The
??>>>>> only down side its that its bulkier than an non-self inflating bag
??>>>>> and I can live with that.

??>>>> Do you use a slob knob Al?

AA> You're trying to compare self inflating bags to slob knobs? You're
AA> kidding right?

Your arguments for the DSMBi; appear to be remarkably similar to the
reasons people use defending slob knobs; it is easier, less faff,
reliably faster, more comfortable.

??>>> Slob knobs break.

The DSMBi has a number of additional ways in which it can fail compared to a
simple bag. Forget to fill the bottle, fail to tighten the bottle, leaks,
accidental operation.

??>>>You can always manually inflate a DSMBi.

The Slob knobs I have come across have a knurled ring for use should the
cable break / foul. Of course if you can reach the knurled ring, why use a
slob knob?

A self closing bag is a very simple bit of equipment. There is virtually
nothing to go wrong during preparation or operation, and everything that can
go wrong applies equally to the DSMBi. If you can breathe into the bag why
use an inflation bottle?

I guess someone that has difficulty reaching their isolator might think it
barmy not to use a slob knob. If you don't have difficulty a slob knob is
superfluous. I don't see this debate as being all that different It's
convenience Vs complexity.

??>> Is that your opinion, Al's opinion or the Inquisition's opinion?

AA> It's certainly my opinion, I'm sure its Jason's opinion.

What is this some sort of virtual ventrilaquist act?

AA> I haven't met the Inquisition, after all their main weapon is suprise
AA> and fear. Sorry, their two main weapons are suprise, fear and ruthless
AA> dedication to the Pope. No, their three main weapons are...

Now theres a picture...John Paul in an aqualung!

I better go find a cumfy chair

Regards
MattS

On 29 Jan 2004 13:23:46 GMT, Alasdair Allan <aa@ukrecscuba.org.uk>
wrote:

>> Is that your opinion, Al's opinion or the Inquisition's opinion?
>
>It's certainly my opinion, I'm sure its Jason's opinion.
>
>I haven't met the Inquisition, after all their main weapon is suprise and
>fear. Sorry, their two main weapons are suprise, fear and ruthless
>dedication to the Pope. No, their three main weapons are...
>

And NOBODY expects the spanish inquisition!!

Pete S.

<Pete S.> wrote in message news:40197e56.30476015@news.clara.net...
> On 29 Jan 2004 13:23:46 GMT, Alasdair Allan <aa@ukrecscuba.org.uk>
> wrote:
>
> >> Is that your opinion, Al's opinion or the Inquisition's opinion?
> >
> >It's certainly my opinion, I'm sure its Jason's opinion.
> >
> >I haven't met the Inquisition, after all their main weapon is suprise and
> >fear. Sorry, their two main weapons are suprise, fear and ruthless
> >dedication to the Pope. No, their three main weapons are...
> >
>
> And NOBODY expects the spanish inquisition!!
>
> Pete S.

you really had to be there but read SMB deployment on Thursday:
http://www.outlawdivers.org.uk/notmu...=&menu=reports

On Thu, 29 Jan 2004 14:38:37 +0000, matts wrote:

> The Slob knobs I have come across have a knurled ring for use should the
> cable break / foul. Of course if you can reach the knurled ring, why
> use a slob knob?

Except that if you're using a slob knob, you've probably got the knob
pointing down. So you won't be able to reach it if it breaks. If you've
got it pointing up, it's an entanglement hazard and it will still be
harder to use the knurled ring than an conventional tank valve.

From the few people I know who use them, failure rate seems to be pretty
high.

> A self closing bag is a very simple bit of equipment. There is
> virtually nothing to go wrong during preparation or operation, and
> everything that can go wrong applies equally to the DSMBi. If you can
> breathe into the bag why use an inflation bottle?

All the failure modes you listed can be avoided by putting it together
properly. If it doesn't work, it's not a big deal, unlike not being able
to turn off your leaking gas. You just use your spare or your buddies. You
need a fallback because there's always a chance of a reel jamming or a
boat cutting your line.

I find it very strange that someone who has no problem filling a DSMB at
depth by exhaling into it, was last week claiming it was impossible for
him to orally inflate his wing by exhaling into it.

Odd that.

Jason

--
See http://www.scuba-addict.co.uk/ for UK diving reports and the UK
Underwater Visibility Database. View the database or add your own report

J> Except that if you're using a slob knob, you've probably got the knob
J> pointing down. So you won't be able to reach it if it breaks. If you've
J> got it pointing up, it's an entanglement hazard and it will still be
J> harder to use the knurled ring than an conventional tank valve.

J> From the few people I know who use them, failure rate seems to be pretty
J> high.

I have seen slob knobs rigged variously, up and over the shoulder, down and
round the side. What appears to be the common denominator amongst the slob
knob users I have spoken to is they think the risk of not being able to
operate the isolator fast enough is greater than the risk of the slob knob
breaking...and their buddy can always operate the knurled ring if it does.

These people must percieve benefits above your/my method of reaching for the
isolator else they would not be using a remote isolator. Personally I don't
see the benefit (convenience) as being worth the complication.

??>> A self closing bag is a very simple bit of equipment. There is
??>> virtually nothing to go wrong during preparation or operation, and
??>> everything that can go wrong applies equally to the DSMBi. If you can
??>> breathe into the bag why use an inflation bottle?

J> All the failure modes you listed can be avoided by putting it together
J> properly.

Quite possibly this is what a slob knob user might say if you pointed out
the assembly could break, 'not if you maintain it.' And he has a less
efficient fall back, he or his buddy can operate the knurled ring. They are
the reasons I have been offered when I have enquired.

J> If it doesn't work, it's not a big deal, unlike not being able to turn
J> off your leaking gas. You just use your spare or your buddies.
J> You need a fallback because there's always a chance of a reel jamming or
a boat
J> cutting your line.

Right. So all we appear to differ on is whether the fall back need be any
different than the main method. IMVHO if it is good enough to fall back to
it is good enough to use as a primary technique. Even so, if I thought a
DSMBi provided me with significant benefits I would use one, but it doesn't.
I find using a manual DSMB no more a faff than reaching for an isolator.

J> I find it very strange that someone who has no problem filling a DSMB at
J> depth by exhaling into it, was last week claiming it was impossible for
J> him to orally inflate his wing by exhaling into it.

Of course if you bother to read the original thread you will see that I
claimed no such thing. To save you the trouble; I have a problem with
coordination and so struggle with pushing the button at the time I am
blowing. It is not impossible, just not easy.

Breathing into a bag requires zero coordination. You hold the bag open and
breathe out. If you happen to find this more difficult than using a DSMBi
then use a DSMBi, I certainly will think no less of you.

J> Odd that.

Possibly only if your attempting to be inflamatory.

Personally I find it odd that intelligent, experienced divers can find it so
hard to accept that we each have our own strengths and weaknesses and should
adjust our techniues to account for them.

Anyhow I think we have demonstrated adequately what I said at the beginning.

Expressing an opinion on this group that certain personalities do not agree
with often result in being told;
+ You should agree,
+ You are obviously inadequate for not agreeing
+ The technique you find so easy is actually very complex, dangerous and
should not be used by anyone ever

Regards
MattS

On Mon, 02 Feb 2004 01:50:00 +0000, matts wrote:

> round the side. What appears to be the common denominator amongst the slob
> knob users I have spoken to is they think the risk of not being able to
> operate the isolator fast enough is greater than the risk of the slob knob
> breaking...and their buddy can always operate the knurled ring if it

But speed is of the essence when turning off your gas. There were tests in
Diver which showed just how quickly a tank can empty. IIRC you lose a hell
of a lot of gas in under 30 seconds. By the time you're buddy's there, you
could be out of gas.

> Of course if you bother to read the original thread you will see that I
> claimed no such thing. To save you the trouble; I have a problem with
> coordination and so struggle with pushing the button at the time I am
> blowing. It is not impossible, just not easy.
>
> Breathing into a bag requires zero coordination. You hold the bag open and
> breathe out. If you happen to find this more difficult than using a DSMBi
> then use a DSMBi, I certainly will think no less of you.

Oh come on. You don't need to just breath into the bag. You have to get
about the right amount of air into it, hold the reel and then release it.
That also requires some coordination. It's not just a matter of breathing
into a bag.

Not that it's particularly hard, I just find a DSMBi less hassle. I still
use a manual one every now and then, mainly on second dives because I
can't be bothered to refill the bottle.

> Anyhow I think we have demonstrated adequately what I said at the beginning.

Which I think was the point of your posts. You deliberatedly trolled so
so could could prove your point about a group of people ganging up. And
you chose your target well. It's probably the only piece of kit that I
have that Pete and Al also use. Apart from a DSMBi, I don't think I have
any other piece of kit the same as them, possibly one of my reels.

Jason

--
See http://www.scuba-addict.co.uk/ to view UK dive spaces or add your own.