Tip du jour

[Cave Diver]

Uncle Pug once bubbled...

Yes... but you are the one really up late John....
I am a few hours behind you.
And in a few more hours the folks in Thailand will be on board

Yup, but I'm still wired from diving earlier. Was out getting some skills practice in before DIRF this weekend. Don't wanna look like a total klutz, 'specially if I am gonna get my very own copy of the tape.

 

[Uncle Pug]

As soon as we have one depth gauge failure the dive is called. This should be noticed within a five minute period as that is how often we check our gauge.
Ascent begins with a working depth gauge.
Should that gauge fail we will already be on our way up.
Timing the stops would be done with the backup timer.
We would just approximate the 10 feet between stops.
If the double failure occured before the gas switch we would consider that gas lost and go to our bailout table.
If the double failure occured after the gas switch we would make sure that we did not descend(!) and keep to our original plan.
We shoot the bag at the 70' gas switch so that might or might not be taken care of by the time we had the double failure.
We would not use the line as a measuring device nor would we hang on it.


Like I said.... this is something that we are going to practice... and I don't have the DIR answer... I know who does though... and when I get a chance I am going to ask him.

 

[Cave Diver]

Uncle Pug once bubbled...
Like I said.... this is something that we are going to practice... and I don't have the DIR answer... I know who does though... and when I get a chance I am going to ask him.

Be sure to share, I would love to know. As for me, I think it is time to make my descent into bed.

 

[The Iceni]

Uncle Pug once bubbled...
How do you ascend in a controlled manner without a working depth gauge or computer?

Much easier and with far more control than with one says I.

Instead of watch numbers change on a small screen and trying to keep them going the right direction and at the right speed....

I watch the stuff in the water.

Back to the original post! This was illustrated to me so well last w/e when I buddied a relatively inexperienced diver who appeared to be mesmarised by his dive computer during the ascent.

He was up and down like a yo-yo! (and me with him!!!)

Why?

I believe this is because the information the computer provides is always given too late, leading to over correction. There is an inevitable delay of some few seconds (or perhaps milliseconds but there is a finite delay) before the computer averages out all the information and provides the diver with the warning of descent/ascent or rapid ascent and actual depth for him to act upon.

When I ascend, or hold station at a stop, I always use the "crud" in the water as my cue and only glance at the computer/depth guage now and then to check my actual depth and time.

To my mind it is like using the speedometer of a car. The dive computer is very useful as a source of information but there are far more useful pieces of information out there to judge your velocity instantly. Driving a car would be very difficult if you could only use your speedometer!

So Uncle Pug, what is this new method. You are not using one of those programmable depth controlling BCs are you?

Kind regards,

 

[Spectre]

Uncle Pug once bubbled...
We would not use the line as a measuring device nor would we hang on it.

Due to the angle [unless you can do trig in your head], you wouldn't get a truely accurate read, but it doesn't hurt to mark off your line at 10 ft increments....

 

[JamesK]

I have actually had to do this once before. I was on a shallow dive, and forgot to bring my computer. Well, I knew I would be well within an NDL since I was limited to a 45 minute dive, and I was on 36%, so I was not worried. The bottom was at 40 feet, and I stayed about 5 feet from the bottom the entire time. So I timed my ascent from approx 35 feet, and wanted to take two minutes to get to what I felt was halfway for my "safety stop". I used the crud in the water to judge how high I had gone also. I did this buy following specific things floating in the water, and judging the disatnce between them. I then stopped for 4 mintes, and continued up at a slow rate. It took two minutes to reach the surface from their, so I figured I judged the stop at about 15-20 feet.

Would I have done this on a deep dive that would have gotten me close to NDL? No. Would I have done this on the same depth dive if I had not been limited to 45 minutes, and could have approached NDL? No.

 

[Rick Murchison]

My deco spool is knotted every ten feet. Count the knots.
Another method of getting a precise measurement of line deployed (though not ideal 'cause it creates a temporary potential "real mess") is to pull off the amount of line you want, clip off the spool and drop it below - then deploy the lift bag.
We also use marked anchor lines, down lines etc on most sites.
The ascent rate indicator on today's computers is so crude as to be all but worthless.
By the way, while watching the "junk" in the water, take the time to study it... much of it is alive and fascinating. I like to reach out and touch the tiny pieces as they drift by, and am often surprized at just what starts swimming, and how.
Rick

 

[Uncle Pug]

Rick Murchison once bubbled...
My deco spool is knotted every ten feet. Count the knots.

By the way, while watching the "junk" in the water, take the time to study it... much of it is alive and fascinating.

This is one of my favorite parts of the dive... watching the stuff... like you said it is fascinating... I just need to get a magnifying glass that will work well U/W.

The reason we don't knot the spool line is that could impede it freewheeling off the spool. When we shoot a bag we let the spool go until the bag hits the surface... if a knot caused the line to jam the spool would go up with the bag.

That plus the fact that even if currents are not an issue (which they usually are) the surface wind will often pull the bag so the line is at an angle (as Spectre said.)

It really isn't that hard to estimate 10'... Shane is 6'4" so I have him get vertical and hold his scooter over his head.... this is approximately 10'

 

[Uncle Pug]

JamesK once bubbled...
I have actually had to do this once before.

Yeah, I have done this before too... but I can't say that I had too... I mean - the other option was available.

 

[JamesK]

Uncle Pug once bubbled...

Yeah, I have done this before too... but I can't say that I had too... I mean - the other option was available.

Yeah man, I had too! No choice! LOL. The situation went like this, the gauges were in a small box in the truck on shore. My buddy was suppsoed to grab them from the truck. When I aksed him if he had everything, he said yes. We got out and realized, no gauges. It was either dive with someone I did not trust, and did not know, or dive without them. Not diving was not an option! LOL! Like I said, I would not do this if the conditions were not perfect, and it was a long or deep dive.