A peeve but an important one - 20m is NOT 60ft!

[goonsquad]

I'll stick with my Quintal's and Pounce's if you don't mind...

 

[Doc Harry]

Gimme a break.

As a physician, I recommend that you see your doctor for regular injections of a sense of humor, as you are seriously lacking in that element!

 

[Karl_H]

Here is a helpful guide for learning how to convert between imperial and metric, and fahrenheit and centigrade:

Thats brilliant I'm all metric so more used to converting the other way but think the reference points given are way more useful than the normal conversions .....

 

[spectrum]

I see this all the time and it drives me ****ing crazy - including in magazines that should know better. 20m is not anything like 60ft - it's 65ft. A meter is 39 ins, not 36. After a serious dive those three extra inches mount up so catch up!!!

And just how precise do you think dive tables / algorithms are? If you think they are keeping you that close to the edge you're kidding yourself. There are more rounding errors and and assumptions built into that stuff than you can shake a stick at.

Now if the fuzzy math just sets you off so be it. For my sake please don't call your alternate second stage an octopus.

Pete

 

[Karl_H]

And just how precise do you think dive tables / algorithms are? If you think they are keeping you that close to the edge you're kidding yourself. There are more rounding errors and and assumptions built into that stuff than you can shake a stick at.

Pete

Not to mention the effect of high or low sea salinity on the water density and hence pressure at that depth

 

[RJP]

I see this all the time and it drives me ****ing crazy - including in magazines that should know better. 20m is not anything like 60ft - it's 65ft. A meter is 39 ins, not 36. After a serious dive those three extra inches mount up so catch up!!!

Yeah, 60ft is nothing like 65ft! I remember the first time I went down to 65ft - after years of only diving to 60ft. I'm not sure how I fell victim to such a runaway descent. Not sure why my computer didn't start warning me! I guess I should have noticed how much darker it got as I plummeted from 60' to 65ft. I must have been really narc'd, because I covered that entire distance in what seemed like no time. I was confused, disoriented, developed vertigo. My sac rate doubled at that dramatically increased depth. My reg started breathing really hard... in fact my tanks started to buckle under the increased pressure.

The last thing I recall was looking up from 65' and seeing my buddy...way above me in the distance...up at 60' and thinking "I can't believe it's going to end this way." I mean, there I was, in Poseiden's clutches at 65ft, breathing what was surely my last breath, as my buddy watched helplessly from 60ft. It was surreal, though. Calm. As if there was really nothing wrong. As the blackness began to creep in from the edges of my vision, it almost seemed as if I could reach up from the watery depths and take my buddy's hand. I know! Crazy, huh?

Fortunately my buddy recognized I was in distress. (Not sure how, as I was so out of it that I forgot to put my mask on my forehead.) He too reports the strange feeling that he could have reached down and taken me by the hand. Fortunately, he spent a few weeks in Europe during grad school, so using his computer and a dive slate he was able to calculate that, although I appeared to be 1.524m below him, I was actually FIVE FEET below him. He had a decision to make. To abandon his buddy and save himself...or to risk everything. Both our lives flashed before his eyes. He recalled the two of us growing up, fond memories of little league, and high school, then college. He remembered how I was the best man at his wedding, that he was my child's godfather, and then he recalled... that I had his truck keys in the pocket of my drysuit undies!

Taking control of the situation he abandoned all rational thought, and in a "do or die" decision he plunged from 60ft to 65ft! He somehow managed his own descent to be able to slow and stop at 65ft, and grabbed me by the tank valve while deftly venting his wing. He had to struggle a bit to find my inflator hose - a miracle in itself since he had no idea I had recently changed from the 16" version to a 14" version. Now two inches doesn't sound like much, but keep in mind that at that depth two inches is actually 50.8mm!

With incredible skill and precision, he carefully managed a controlled ascent - flaring the whole way I can only presume - and safely brought us up from from 20m all the way to 18.288m. He even ensured that we did a "deep stop" at 19.144m - no sense in risking microbubble formation by coming up so fast!


:cool2:

 

[miketsp]

I don't mind so much the depth rounding but whenever I go to the Caribbean and ask for Y KG and they give me 2 x Y LB that just doesn't work! :depressed:

 

[Scott L]

Yeah, 60ft is nothing like 65ft! I remember the first time I went down to 65ft - after years of only diving to 60ft. I'm not sure how I fell victim to such a runaway descent. Not sure why my computer didn't start warning me! I guess I should have noticed how much darker it got as I plummeted from 60' to 65ft. I must have been really narc'd, because I covered that entire distance in what seemed like no time. I was confused, disoriented, developed vertigo. My sac rate doubled at that dramatically increased depth. My reg started breathing really hard... in fact my tanks started to buckle under the increased pressure.

The last thing I recall was looking up from 65' and seeing my buddy...way above me in the distance...up at 60' and thinking "I can't believe it's going to end this way." I mean, there I was, in Poseiden's clutches at 65ft, breathing what was surely my last breath, as my buddy watched helplessly from 60ft. It was surreal, though. Calm. As if there was really nothing wrong. As the blackness began to creep in from the edges of my vision, it almost seemed as if I could reach up from the watery depths and take my buddy's hand. I know! Crazy, huh?

Fortunately my buddy recognized I was in distress. (Not sure how, as I was so out of it that I forgot to put my mask on my forehead.) He too reports the strange feeling that he could have reached down and taken me by the hand. Fortunately, he spent a few weeks in Europe during grad school, so using his computer and a dive slate he was able to calculate that, although I appeared to be 1.524m below him, I was actually FIVE FEET below him. He had a decision to make. To abandon his buddy and save himself...or to I risk everything. Both our lives flashed before his eyes. He recalled the two of us growing up, fond memories of little league, and high school, then college. He remembered how I was the best man at his wedding, that he was my child's godfather, and then he recalled... that I had his truck keys in the pocket of my drysuit undies!

Taking control of the situation he abandoned all rational thought, and in a "do or die" decision he plunged from 60ft to 65ft! He somehow manage his own descent to be able to slow and stop at 65ft, and grabbed me by the tank valve while deftly venting his wing. He had to struggle a bit to find my inflator hose - a miracle in itself since he had no idea I had recently changed from the 16" version to a 14" version. Now two inches doesn't sound like much, but keep in mind that at that depth two inches is actually 50.8mm!

With incredible skill and precision, he carefully managed a controlled ascent - flaring the whole way I can only presume - and safely brought us up from from 20m all the way to 18.288m. He even ensured that we did a "deep stop" at 19.144m - no sense in risking microbubble formation by coming up so fast!


:cool2:

 

[HIGHwing]

By the time you account for the variance of wave height, and the difference between standard and actual atmospheric pressure/temperature, I figure you're going to be just fine.

 

[D_B]

my rule of thumb for converting mm's to inches ... works very good in day to day stuff

25mm = 1"

and my "formula" to keep a rough grasp of temperature ...

28c = 82f (reverse the numbers)


BTW ... "The metric system is the tool of the devil. My car gets forty rods to the hogs head and that's the way I likes it!" (Simpson's reference for the heck of it)