Re: Computer And No Console

Lazarus X wrote:

> Seriously though, my opinion is that an SPG is a nice simple device
> that tells me how much gas I have left at a glance (i.e. 2/3s between
> empty and full). It never requires a back light and the batteries
> never fail, A gas integrated computer requires a subconscious
process
> to work out what numbers like 120 mean (you analogue brain needs to
> work out how full or empty the tank(s) are). It requires a back
light
> and the battery may fail. If the battery fails on my computer, I
> switch to my backup tables, if they fail on a gas integrated
computer,
> I would have to switch to tables (assuming the dive is not no-stop -
> note: why am I using one of these things for deco diving?) AND I have
> to worry about how much gas I have left which will probably increase
> my breathing rate which will make me worry more about how much gas I
> have left. The solution is a backup analogue SPG. If I am carrying
> an analogue SPG as a backup then I may as well use it as a primary
(as
> it is more reliable) and ditch the air integrated computer and save a
> few £s in the process.
>
> The down side? If I don't use a gas integrated computer, I won't
know
> the time to die! IMO a gas integrated computer introduces far too
> many failure/complication scenarios when there is a cheaper more
> effective solution available.

Firstly, although you lose some reliability from having a battery, you
gain some from losing a hose + O-rings. If your battery fails, how much
gas do you have left? Enough to get you to your next stop (which at
that point is all you need to know because the dive is over) - you
planned the dive. If your SPG fails due to a catastrophic hose failure,
you've got a bigger problem.
So you're making it slightly more likely that you'll have to exit the
water, in exchange for making the worst possible failre less likely.
Secondly, if you don't know what "200 bar" means in terms of empty/full
without having to think for too long, you probably shouldn't be diving,
so analogue v digital readout is pretty much a non-issue. Backlight:
You're going to have to turn it on anyway to check your no-deco time so
you lose nothing by checking your gas at the same time.

I carry both. The reason I carry my SPG is that it's an easy way to
tell somebody else how much gas I have, or ask somebody how much gas
they have.
When I'm no longer training I'll probably remove it.
And personally I always use my computer to see how much gas I have left
- since I'm checking no-deco time / deco information / depth anyway, I
may as well know how much gas I have left and vise-versa. It's also on
my wrist - which is nice.

Alun Harford

alunharford@yahoo.com wrote:

> Secondly, if you don't know what "200 bar" means in terms of empty/full
> without having to think for too long, you probably shouldn't be diving,
> so analogue v digital readout is pretty much a non-issue.

It's a bit more subtle than that though. Although here in Europe we use
bar pretty exclusivly, in the states and the carribean PSI are far more
common. Although multiplying by 14 isn't that tricky, I reckon it is
simpler for a foreign buddy to work out what is going on with an
analogue spg - Full, half full, quarter full is easier to interpret than
a number which doesn't correspond to something you're familiar with.


Ben


--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Ben Panter, Edinburgh, UK
email is false. Use my name (no spaces) at bigfoot which is a com.

-----------
Firstly, although you lose some reliability from having a battery, you
gain some from losing a hose + O-rings. If your battery fails, how much
gas do you have left? Enough to get you to your next stop (which at
that point is all you need to know because the dive is over) - you
planned the dive. If your SPG fails due to a catastrophic hose failure,
you've got a bigger problem.
-----------

And how do the transmitter's fit into the first stage? With o-rings by any
chance?
And as it's a rigid thing sticking out from your first stage, if it gets
knocked then its going to be much less forgiving than a hose that can just
bend out of the way.

David

"David Walker" <wbsdavenews@hotmail.com> wrote in message
news:413d8ea6$0$16901$ed2619ec@ptn-nntp-reader01.plus.net...
> -----------
> Firstly, although you lose some reliability from having a battery, you
> gain some from losing a hose + O-rings. If your battery fails, how much
> gas do you have left? Enough to get you to your next stop (which at
> that point is all you need to know because the dive is over) - you
> planned the dive. If your SPG fails due to a catastrophic hose failure,
> you've got a bigger problem.
> -----------
>
> And how do the transmitter's fit into the first stage? With o-rings by
any
> chance?
Yep. Many SPGs have are 1st stage - connection - hose - connection - SPG
(although some avoid this now I'll admit, which is good - as you've only got
an extra hose to fail in exchange for a battery).
AI computers are 1st stage - connection - transmitter.

> And as it's a rigid thing sticking out from your first stage, if it gets
> knocked then its going to be much less forgiving than a hose that can just
> bend out of the way.
It's a large chunk of metal made to take 300 bar. When do you hit *your* kit
with sledgehammers?

Alun Harford

> It's a large chunk of metal made to take 300 bar. When do you hit *your*
> kit
> with sledgehammers?

Never, but other people's kit however... ;o)

David

> It's a large chunk of metal made to take 300 bar. When do you
> hit *your* kit with sledgehammers?

There are different types of loading. You can load something axially,
rotationally (torque) or you can try to bend it (I forget the technical term
for this). Just because something is designed to take an axial load of 300
bar, does not mean that it can necessarily take any other type of load of
that magnitude.

I can say that with confidence, having managed to screw a hose in so tightly
that it sheared off (the first UKRS SETT dive). I've also had a manifold
bent, though I'm not sure how. I am, however, pretty sure that the bending
force applied was nothing like 300 bar. It's extremely easy to bend a
manifold when assembling a twinset, if one is not careful about keeping the
tanks aligned. Again, considerably less than 300bar need be applied.

As for sledgehammers, consider a scenario that I have seen. a scuba set is
assembled on a boat, is untied from the side and an unfortunately timed wave
hits the boat. The set pitches forward, landing on it's regulator. Now
imagine that the impact was taken on the transmitter. Think it would
survive?

Iain

Iain Smith wrote:
>> It's a large chunk of metal made to take 300 bar. When do you
>> hit *your* kit with sledgehammers?

> As for sledgehammers, consider a scenario that I have seen. a scuba set is
> assembled on a boat, is untied from the side and an unfortunately timed wave
> hits the boat. The set pitches forward, landing on it's regulator. Now
> imagine that the impact was taken on the transmitter. Think it would
> survive?

Yes but that same scenario will trash the camera it lands on at ten times
the price. You can break anything in a 'what if' case. I've yet to see an
AI sender broken, it must happen but not near me yet, so I don't think
that is an argument against them.
If all I was doing was single mix diving I'd quite like the gas used
on the computer dump but these days I don't use gas so it's no longer
relevant. Actually I would far prefer the computer on my wrist so I would
go for a sender rather than a dangly AI.

However I would not like the 'all the eggs in one basket' approach of
putting all my instrumentation in one place on one battery. I got
whinged at because I has two SPGs on the twinset, one of which was an
SPG/depth gauge mini console, but I argued that if I needed something
I took two.

This seems a reasonable take on making a holiday rig where diving is
not the prime object but something you hope to squeeze in. Taking your
own regs/BCD with an AI sender attached is going to be far more
reassuring than hiring beat up warm water dive center kit.

nigelH
http://www.nigelhewitt.co.uk/stuff/manifold1.jpg

> http://www.nigelhewitt.co.uk/stuff/manifold1.jpg

I'm sure I asked last time I saw this one, but with my failing memory...

....how?

CAS

CAS wrote:
>> http://www.nigelhewitt.co.uk/stuff/manifold1.jpg
>
> I'm sure I asked last time I saw this one, but with my failing memory...
>
> ...how?

That's what it was like when I unwrapped it.
I emailed this picture to Kent Diving who said
"Don't do anything to it. We are sending a
replacement."

Actually I talked them into just sending a
new manifold and we were very happy together
for years. I was a bit worried the shipper
might trash the next one.

On the basis of that I have happily used
Kent Diving ever since. How a cut price
supplier reacts to a problem is very important
if you don't want burnt fingers.

nigelH

> That's what it was like when I unwrapped it.
> I emailed this picture to Kent Diving who said
> "Don't do anything to it. We are sending a
> replacement."

What the hell did the courier do to it?

"Here, Charlie, grab a hold of this, its not that heavy..."

*boing!*

"F**k!"

"Hahahahahaha!"

> How a cut price
> supplier reacts to a problem is very important
> if you don't want burnt fingers.
>
> nigelH

I subscribe to that view 100% and not just for discounters.
I accept that people f**k up, I f**k up (regularly), everyone f**ks up.
F**king up is never the problem.
How people put it right when they do f**k up is what counts!

CAS