Are dive computers making bad divers?

[boulderjohn]

When I took the Deep Diving specialty, we derived from the basic physical laws the differential equations that produce the values in the tables and the algorithms in the computers.

About 20 years ago, a calculus teacher in my school district made a serious blunder. He assigned his students to interview people who use calculus as a part of their jobs. He lived in a good area for this to happen. We have several local companies, for example, that are active in the aerospace industry, building equipment that is regularly carried on space flights.

The problem was that the students could not find anyone who was using calculus in their jobs. These engineers said they rely on computer software to do that work, and many said they had not done any of that math in many years.

So what is the benefit to the diver of "deriving the basic physical laws the differential equations that produce the values in the tables and the algorithms in the computers?"

 

[drrich2]

Some of what we learn in school is intended to prepare some (not all) of us for higher level courses; if we don't take those courses, the knowledge atrophies & becomes useless.

High school algebra can introduce us to exercises in logical, deductive thinking, using what we know to figure out some of what we don't (e.g.: solve for 'x'). But most people won't consciously use formal algebraic equations on a regular basis.

On the other hand, if you take collegiate course work in Mathematics or other hard sciences (e.g.: Chemistry), you may need that preparation. Way back in college, I took Multidimensional Calculus as a pre/co-requisite for Physical Chemistry I & II. Today, I don't remember what to do with integrals; IIRC it represents the area under a curve & is sort of the reverse of a derivative? But I can't apply that.

People programing the devices that use the calculus may need to know some. People designing new theory & technology may also need some.

My point is, some topics are taught to a range of people with the understanding many of them will not benefit from it. Just what level of return on investment is necessary to justify doing so is a matter of debate.

Richard.

 

[boulderjohn]

My point is, some topics are taught to a range of people with the understanding many of them will not benefit from it. Just what level of return on investment is necessary to justify doing so is a matter of debate.

Modern curriculum design theory has designers start by identifying the learning that is essential for the course and then making sure the course focuses on making sure that is mastered. then they identify the material that is good to know, nice to know, unimportant, and (finally) off topic.Those topics should be stressed or eliminated in that order.

One of the reasons for that is interference theory. Time and effort spent learning that which is unimportant or off topic interferes with the student's ability to learn that which is both essential and good to know. It also causes students to forget the important stuff too easily.

Another reason is that adding requirements that are unimportant to the learning can keep the student from achieving that which is important.

As an example of the latter, I know several people who are business owners now and have been for several years. Their businesses are reasonably successful, but they are hampered by the fact that they do not have much formal training in business theory and practice. When they went to college, they wanted to take such courses because they intended to be in business after graduation. They could not, however, take a business program at their colleges, because to be a business major or minor there, you had to have completed second year calculus. These people were not strong enough in math to pass classes at that level. They are plenty strong enough in math to handle any math required to run their businesses, but second year calculus? Nope.

I asked a business faculty member of another college why their schools had this prerequisite, and he explained that it was a filter to limit the number of people taking the classes. Without that filter, they would have many more business students than their current faculty load could support. I asked him why they did not require a 2-mile swim as a filter instead. He said swimming had nothing to do with business. I said neither did second year calculus. In these cases, a requirement that had nothing to do with the education program was preventing capable and motivated students from taking classes they truly wanted and truly needed.

If you have the time to add something like that to a course, if the students have the ability to learn it without interfering with the rest of the learning, and if they are interested, then go ahead and add it. Otherwise, best to consider dropping it.

 

[TMHeimer]

Agree with what Neilwood and others say in that whether you use tables or computer, you just need to know what you need to know. The "whys" may be interesting, but not very necessary. Others referred to academic subjects. I probably used 20-30% of my college music course knowledge while teaching Band. Likewise, at least in the "old" DM course there was a lot of very interesting stuff--much of it I have yet to use while assisting with courses. There have been times when I could elaborate on a subject (both with music and dive courses) when a student asked a more advanced question. But that's in addition to the stuff the student needed to know.

 

[Rhone Man]

Mathematics is the universal language of science. I appreciate that most people do not grow up to be scientists, but if no one grows up to be scientists then we are f***ed. Who will write the software that does the maths for people then?

Just sayin'. Back to your regularly scheduled programming.

 

[BHB ScubaTroll]

Wow!... and the beat keeps runnin', runnin', and 'runnin', 'runnin'... Is this still in the "basic-scuba-discussions" area, or the PUB?

 

[Steve_C]

See lots of design oriented engineers using calculus but they often use different words like marginal rate of return or velocity, or acceleration or flow rate.

There is also lots of math I learned in college that I never use anymore and I am a professional mathematician. Doesn't mean the time was wasted. I also learned how to play ice hockey and I do not do that anymore. Not a waste. Part of the journey.

 

[miketsp]

I would say that for the average OW diver knowing the maths behind how the tables were achieved would be way too much. I doubt most vacation/occasional divers want to get in to differential equations.

All most divers need to know is the following:

• ..snip..
• if you are going to err, do so on the side of safety ie longer stops/slower ascent etc

Now if you want to go deep or tech, knowing the additional information would probably be useful

Rather than saying "slower" ascent I'd prefer to see "correct" ascent rate.
As you get into deeper dives (30m+) you don't want to be hanging around at depth once your planned bottom time has expired. Too slow ascending at depth and you can easily create an unexpected deco obligation - even though you're ascending. On-gassing of slower compartments can still be happening even though faster compartments are starting to off-gas.
Go as slow as you like on the shallow part of the ascent - too many divers rush the last 5m after the last stop.

---------- Post added December 18th, 2015 at 08:33 AM ----------

Mathematics is the universal language of science. I appreciate that most people do not grow up to be scientists, but if no one grows up to be scientists then we are f***ed. Who will write the software that does the maths for people then?

Just sayin'. Back to your regularly scheduled programming.

As Hawking and many others have stated, "Creation of Artificial Intelligence will be the biggest event in human history, unfortunately, it may also be the last" so don't worry..

 

[CuzzA]

As Hawking and many others have stated, "Creation of Artificial Intelligence will be the biggest event in human history, unfortunately, it may also be the last" so don't worry..

You mean the fact that Google is Cyberdyne. I believe they have acquired 8 AI companies now and they have a pretty good grasp on the net. :shocked2:

[video=youtube;-e9QzIkP5qI]https://www.youtube.com/watch?v=-e9QzIkP5qI[/video]

There once was a time when many believed knowing how to operate a computer meant you were smart. I use my computer. I was never taught tables, but they're so simple I just did a little "Cyberdyne" search and figured it out in like two minutes. I have since laminated tables as a backup and keep them in my gear bag.

---------- Post added December 18th, 2015 at 09:15 AM ----------

For those that hate computers, just wait until you run into someone diving with his robot buddy.

[video=youtube;wq-wQVeB-kY]https://www.youtube.com/watch?v=wq-wQVeB-kY#action=share[/video]

Robotic Dive Buddy Developed from Underwater Drones Aids Solo Divers | Scuba Diving

CADDY ? Cognitive Autonomous Diving budDY | CNR ISSIA

 

[CAPTAIN SINBAD]

This thread shows that there is a significant diving population out there that does not understand how tables work. Yet they are convinced that they understand how decompression works. In other words they have understood how decompression manifests itself on the computer display while having no understanding how it manifests itself in the form of parallel columns where depths meet No Deco times!

I am not suggesting that they are bad divers because in the age of computers, you can buy a computer for less price than a bottom timer (seriously) but it is still important to know what our computer is doing to decide what value we wish to attach to that service.

While I dive with a computer, I have the following NDLs memorized in my mind. I remember this table listed below just like I remember my mothers name.

DEPTH(ft):TIME (mins)

60:60
70:50
80:40
90:30
100:25
110:20
120:15
130:10

This means that holding a computer or even looking at a table in dives shallower than 60 feet is totally useless as long as surface interval is more than an hour and dive is less than an hour.

On dives deeper than 60ft, the memorized table means that as long as I do not exceed the depths in the left column I can stay in the water for the duration on the right column. Once memorized, this is purely instinctual and habitual and requires no math, computer or tables. Just pure memory.

Since these are squared out linear profiles, it can be argued that holding a computer in my hand will allow me to extend those times a little more due to the multi-level nature of most dives. In other words,if I am diving a wreck that is 100 feet to the sand and the top of the wreck is at 80 feet and I am exploring the entire wreck going up and down then computer might let me prolong the overall dive of 25 minutes to a few more minutes.

True but hold on ...

There is a simple method called Depth Averaging that magically gives you those "lost minutes" that your computer will eventually arrive to after "real time depth calculations. A mathematical average is defined as the sum of all the numbers on a list divided by the total number on the list. In case of the wreck which starts at 80 and ends at 100, we will add 80 + 100 and divide that by 2 to get to 90 feet. From memory, I will know that I can now stay for 30 minutes instead of 25.

Instead of calculating NDLs using maximum depth of 100 feet now and then ending at 25 minutes, we can use averaged out NDL of 90 feet and finish the dive in 30 minutes. 5 minutes will be added by this highly idiotized and over simplified math of depth averaging and as long as you don't go above the top of the wreck (80 feet as there is nothing there anyways) and you don't go below sand (100ft because you cant) your computer will also add around 5 minutes to the dive with all that "real time and depth calculations."

So depth averaging is a simple way of adding those lost minutes for which we normally carry computers. For someone properly trained on tables, the computer really does not do anything for the first dive. It shows its value on the second dive by saving the need to cast that one glance at the new NDLs on the table which replaces the ones memorized for your first dive. After a few dives on tables that occasional glance may not even be necessary.

Once the above is understood, each person can then decide how much value they assign to this simple function being performed electronically.