Deco dive plan sheet

[Randy43068]

Now, you keep that up, and I'll invite some of the "Do / Don't teach tables in OW" crowd in.

But seriously -- learning to do it long-hand in the classroom makes sense, doesn't it? Especially if you incorporate the results of vPlanner and dive computers?

Absolutely! Understanding the academics of dive planning is a given. Once understood, it's insane to do all that planning long hand.

I can do gain/freq/roll-off calcs for filters long hand, but what's the point? To my mind, it's the same thing. Modern tools with proven results are the thing to use.

 

[Trace Malinowski]

When I took my NACD cave class, my instructor insisted that I do dive planning sheets and check them against V-Planner. During training, the exercise can become a valuable tool for visualizing the dive, verifying certain aspects of the plan, and making sure you haven't missed any details. I'm not just talking about things like gas management or mixes or oxygen/nitrogen loading and the info found on the sheet, but the time that it takes to complete will often focus the mind on the dive plan long enough to create a pretty detailed mental picture of anything you may have left out.

When I first started teaching technical diving I employed worksheets because they were educational. Students seemed to develop greater confidence in their math and planning abilities when their calculations and the dive planning software used were very similar. They gained a greater understanding of how a neo-Haldanean model and a bubble model will approach the decompression curve.

I got away from sheets and just focused on using dive planning software and ratio decompression, but discovered that most of my technical students who have come from GUE nearly fail the written examinations for advanced nitrox and trimix. For example, if a question asks the student to calculate the EAD of Nitrox 32 at 100 feet and determine the decompression plan, nearly every GUE student will mentally do a 20% reduction in depth, arrive at 80 feet and plan the dive as an 80 foot dive. In reality, the correct answer would be 81.48 feet and would be rounded to 90 feet on a table. For this reason, I'm bringing tables and planning sheets back to classes.

While battlefield calculations are excellent to use underwater and ratio decompression allows a dive team to intelligently change the dive plan underwater, it's unfortunate when those awesome "on the fly" tools create confusion or mistakes in the proper use of basic dive tables. Newer tech divers, or even recreational divers who haven't purchased computers yet, might look to experienced technical divers for help with dive planning. Basic dive planning and table use should be learned well if for no other reason than to help others safely plan their dives.

For experienced technical divers, thoroughly using planning sheets and tracking your RMV from time to time helps you assess your abilities as you age or as your fitness level changes. Some people may still think their RMV is like .4 twenty years later.

 

[HowardE]

How about you guys that mix your own tri-mix gasses? What do you mix? Standard or custom?

The right gas for the dive.

 

[ucfdiver]

Now, you keep that up, and I'll invite some of the "Do / Don't teach tables in OW" crowd in.

But seriously -- learning to do it long-hand in the classroom makes sense, doesn't it? Especially if you incorporate the results of vPlanner and dive computers?

What are you checking against vplanner? That USN tables look nothing like VPM-B? I guess I don't understand how you can check against a totally different decompression profile

 

[Jax]

What are you checking against vplanner? That USN tables look nothing like VPM-B? I guess I don't understand how you can check against a totally different decompression profile

No, hon; not "check". We discuss the different results and the reasons . . .

 

[Blackwood]

The right gas for the dive.

Why Howard, didn't you know that "right" is an inflammatory term that should be avoided?

 

[Dive-aholic]

While I do cover tables in class and the exams my students take do have them calculate deco schedules, cns%, and otu's, when planning dives they have to use software. If they can't afford software they shouldn't be doing this kind of diving. It's no longer hundreds of dollars to get a set of tables to do one dive. It's a matter of spending under $100 for one of the more popular programs available. There are just too many people out there that are mathematically challenged. That's not something I'm going to be able to change. But I can make sure they use tools to plan their dives that won't get them bent because they screwed up an equation or 2. You can understand the concepts without having to cut tables manually. Use the tools we have available.

 

[ScubaFeenD]

.

I got away from sheets and just focused on using dive planning software and ratio decompression, but discovered that most of my technical students who have come from GUE nearly fail the written examinations for advanced nitrox and trimix.

There's that damn GUE again, screwing with proper tech diving.

 

[Blackwood]

The 5% drop in O2 is what is generating the 27min differences.

Of course, that's the point. Whatever gases one calls standard, any time you elect to use a single gas over a range of depths, the po2 at the shallow end of that range will be at a deficit relative to a single gas selected at max po2 for that depth.

Those dives are well beyond my training and experience, but if someone said "dude you have to come see this wreck at 300, it'll blow your mind," I may go for the specific gas approach over the standard gas approach. It's a one-off that I'll never repeat, so what do I gain by using the standard gas? Nothing. Can I figure it in my head? Sure, but just as sure I'll triple check it against software.

It's a numbers game, and a magnitude one at that. 20%
more deco... who cares/1.2 times what?

30 minutes more deco... I care, particularly if it comes with no benefits to me.

 

[Sat Diver]

I would always plan these by hand. I would check my hand solutions by doing my calculations a second, different way. And then check again by comparing my solutions to my buddy's hand-calculated solution.

Being a former computer programmer (my first degree and my first job), I *know* there are hidden assumptions coded into computer programs. When I generated my solutions by hand, I was more confident about the presence or absence of hidden assumptions.

Ronald

Hey Ronald,
Big admiration here for anyone who can do that, but for those of us (hopefully a small minority here) who are not well educated ( started surface supply air diving out of high school) and cannot trust their own math, a computer is the way to go if you dont have a dive supervisor with a master blender on the surface telling you what to do and altering your mix through the umbilical.
Equations give me a headache and remind me why I ran away from school and became a diver in the first place