Re: DIR question

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Posted by tleemay on December 24, 2000 at 13:53:31:

In Reply to: DIR question posted by Max Bottomtime on December 22, 2000 at 14:58:16:

My what an interesting topic from this group...
and those responses - glad to see people have been
doing their reading!

I'm going to primarily address this from a sport
diving aspect - and I'll gently touch on the tech
diving advantages here and there. When MHK get's back
from NY, I am sure he will chime in with more

First off Max, what do you consider a "properly
attatched console"? If you just mean kept off the
bottom, there are many ways to just do that. But what
the DIR practice gains in advantage you might feel
lost in your application. Therefore I highly suggest
trying what I am about to describe as just talking
about it does not do the topic justice.

But (pun intended - read on), if you mean "properly
stowing" in the way a certain MJBlackMD prefers,
this discussion is over - butt crack stuffing of
the console is not worth discussing ;-).

Looking at your slipstream as you dive, anything you may
have clipped off to your chest is interferring with
the slipstream your head and shoulders cut as you
swim along. The area of the chest must be kept clear.
If you are the kind of diver (and to my knowlege, you
and I have never met, nor been on the same boat together)
that like to clip your console to your
chest, with or without a retracting device, you are
adding drag. Again - keeping the chest area clear is mandatory
in being efficient in moving through your water. It
doesn't take much displacement to cause this loss of
efficiency. The console creates as area the water must
go around and therefore defeats the efficiency of the
slipstream by just being there. It's further defeated
by the diver grabbing it, pulling it off the chest to view,
and then replacing. What little efficiency the console
did have (if any) while firmly against the chest
is lost as the colsole is brought out of the slipstream
as viewed and then replaced. I akin it to putting
up a small sail and then retracting it - pull the
console away to view and then putting it back.

Having the console stowed in a BC clip or a retractable
cord off the left side is *slightly* more
efficient, but still the whole effect of pulling
out a console that's larger than a single gauge,
viewing it, and then either putting it back in the clip
or allowing the retarctor to do the job for you causes
still more drag and efficiency loss than desired.

There is also the snag issue. I usually always
see divers coming in from their divers with their
consoles unclipped and banging on the swim step,
against the ladder, or as they sit into their station.
Most of these divers also do not clip off their
gauges before they even get into the water. I used
to make it a habit of asking a diver with an
unclipped console if they want it secured.
They usual answer in action in that they grab it, put
hold it against their weightbelt buckle and jump.
When they return, there it is flopping in the wind. I
have been in the water and watched consoles and gauges
get caught in kelp, bang on the reef and rocks, get
lost behind the diver, etc. Now the gauge can cause
other problems other than diminish drag efficency.

A single HP hose of the proper length clipped off
to the left hip d-ring can be out of the way within
the slipstream and yet be viewed by the diver just
looking down at the d-ring. No unclipping or clipping
and no retractor gizmos to pull and stow (and possible
fail - yes I have seen it happen). Also, if you were
doing a tech dive in a restriction, you can easily
unclip the gauge, bring it to your face and read it.
It becomes second nature with practice to re-clip it
after viewing. The spg gauge is also without boot
so that HP wrist pin problems can easlily be spotted.
The lack of boot also does not allow sand and other
debris to collect between it and the gauge. I just
recently purchased two new brass Scuba Pro HP gauges
for my technical and sport diving kits. The first
thing I did before I put them on the regs was cut
off the rubber boots - since the gauges are not
banging into other things, they are not needed. And
as I wrote earlier, the boot just hinders hose to
gauge inspection underwater.

Now what would you do with your computer or bottom timer
and compass if it's not in a console? It get's bungied
to your right wrist or upper forearm. The reason why
it's there is that you can look at it anytime without
having to reach for the console is mounted on your chest
or left side.

As someone else already pointed out, one
of the main reasons why it's on the right arm and not
the left is that when scootering, or running a reel,
techdivers like having everything in front of them
so it can be viewed on the fly. When scootering
with one hand, it's usually the right hand on the scooter
- which puts the right arm gauge right in front of
tem. The reason why it's bungied is because all
rubber straps will eventually break. Bungied devices
use the same mounting boot, but have two separate pieces
of bungie atatched to it. There are a couple different
ways this is accomplished, but the tried and true
way is to puncture two holes on each side of the boot and
insert one end of each bungie into each hole. A knot is
tied on the other end of the bungie where it passes
through the boot. In this configuration, you now have
two independent bungie straps hoilding the console to your
arm. Should one of the bungies break even though you are
suposed to be performing regular inspections to your
kit before and after every dive, the other will still
keep the boot on you until you get back to the surface
and facilitate bungie replacement. Another two reasons
for bungie cord in this application are also cost (about
$1 worth of bungie with do one bottom timer/compass) and
depth compensating property (always streatched and
holding the boot close to the arm - great when diving dry).
The boot can also be easily rotated inside the arm to further
decrease drag and the snag factor. I find this
particularly an advantage when reaching into holes
during a lobster hunt. I have rotated the boot behind my
bicep and as high up the arm as possible. Typically
I keep mine on the inside if my upper forearm until
I reach deco (when tech diving), I them rotate it more
toward my wrist and in more of a watch position so that
I can easily monitor deco depths and times while hanging
onto a down/anchor or jon line. Once again I'm not
unclipping/clipping a console to get info, it's just
right there in front of me.

The compass is mounted in the same type of boot and fashion
but on the left arm. This is an advantage for those who dive
with scooters in that it does allow one to take a bearing
while at the same time drive the scooter with the right arm.

As a side note - when JJ was out here last, JJ ,his friend
Mark, MHK and I had a brief discussion of the improtance of
a smooth slipstream as it applied to divers. I recall Mark
saying the findings of a UCLA study of some kindshowed
something to the effect that displacement and subsequet drag
value squared (d2) required additional energy cubed (e3) to
negate the effect - or words to that effect, so don't hold
me to that. But it's something to keep in mind if even
remotely applied here.

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