Rental computers and newer divers

[Mrs. B]

Do you use that on all dives? Even 2nd and 3rd dives? What do you do for surface intervals?

No

I use a Suunto but always have the 120 running in my mind

I believe it’s a good idea to have an idea where you are without a computer even when using it.

To be clear, I have been diving since before computers because I was taught by my dad who was an old school Florida cave diver

Eight years in the Caribbean, I’ve done a lot of diving without a computer (80s)

 

[lowwall]

I was not around when people were actually diving tables. I only started diving in the late 1990s. Like many other divers over the next decade and even now, I was trained to use the tables, but when I started doing the DM-led dives in Cozumel, I learned on the first dive that they were worthless for multi-level diving. I bought a computer as soon as I could, and I struggled through the nearly incomprehensible manual to understand how to use it. My attempt to use it after my first Cozumel dive remains to this day the only time I have seen anyone use tables outside of training dives.

The reality is that DM-led dives in places like Cozumel are going to be reasonably safe with or without a computer as long as you use a little bit of common sense. Common sense mostly means staying about the same depth or shallower than the DM.

If you think about it, the DMs not only want to keep the divers safe, they have to learn to tailor their profiles so that none of the common computers go into deco. The normal deep Coz dive, for example, will only have a few minutes at the deepest part and then a leisurely ascent to somewhere in the 60-70' range for many minutes and then another bunch of time around 30'. Second dives are almost always shallow as are afternoon and night dives. Even outfits like Aldora, which prides itself on the length of its dives, will have a lot of that extra time spent drifting along at the nitrogen loading equivalent of safety stop depth given their high 02 level nitrox mixes.

Even wreck dives in vacation spots are as SurfGF friendly as possible with the DM usually doing a quick lap or half lap at the bottom before moving up to the highest points on the wreck. I'm also convinced that they often they push the speed a bit or expose the group to more current than necessary during the deep part to "help" divers run out of gas before they run out of NDL time.

 

[boulderjohn]

The reality is that DM-led dives in places like Cozumel are going to be reasonably safe with or without a computer as long as you use a little bit of common sense. Common sense mostly means staying about the same depth or shallower than the DM.

If you think about it, the DMs not only want to keep the divers safe, they have to learn to tailor their profiles so that none of the common computers go into deco. The normal deep Coz dive, for example, will only have a few minutes at the deepest part and then a leisurely ascent to somewhere in the 60-70' range for many minutes and then another bunch of time around 30'. Second dives are almost always shallow as are afternoon and night dives. Even outfits like Aldora, which prides itself on the length of its dives, will have a lot of that extra time spent drifting along at the nitrogen loading equivalent of safety stop depth given their high 02 level nitrox mixes.

Even wreck dives in vacation spots are as SurfGF friendly as possible with the DM usually doing a quick lap or half lap at the bottom before moving up to the highest points on the wreck. I'm also convinced that they often they push the speed a bit or expose the group to more current than necessary during the deep part to "help" divers run out of gas before they run out of NDL time.

It almost sounds like you are advocating what many would call "trust me" dives.

Lots of people do that, and it is usually, but not always. safe. I had two occasions (not in Cozumel) in which I had a different DM lead the second dive, and that DM led us on a typical first dive profile, and I had to leave him to his own devices to stay within NDLs.

 

[lowwall]

It almost sounds like you are advocating what many would call "trust me" dives.

Lots of people do that, and it is usually, but not always. safe. I had two occasions (not in Cozumel) in which I had a different DM lead the second dive, and that DM led us on a typical first dive profile, and I had to leave him to his own devices to stay within NDLs.

I'm not suggesting this as a normal practice. I'm trying to explain why you don't have crazy numbers of bent divers in typical vacation destinations despite the issues you noted in the original post on this thread.

 

[dmaziuk]

It almost sounds like you are advocating what many would call "trust me" dives.

Lots of people do that, and it is usually, but not always. safe. I had two occasions (not in Cozumel) in which I had a different DM lead the second dive, and that DM led us on a typical first dive profile, and I had to leave him to his own devices to stay within NDLs.

My recent experiences on Bonaire & Curacao is that the "60 feet limit" is becoming the thing among DMs. Give it a couple of years and it'll be "safe" for 5 dives/day.

 

[Pbdiver84]

It almost sounds like you are advocating what many would call "trust me" dives.

Lots of people do that, and it is usually, but not always. safe. I had two occasions (not in Cozumel) in which I had a different DM lead the second dive, and that DM led us on a typical first dive profile, and I had to leave him to his own devices to stay within NDLs.

The solution for that is to let the dive op know you don’t have a computer and communicate that to each DM at the dive brief.

As for rental computers… with the internet, I’ve found the manuals for every computer I’ve rented and made sure I knew how they worked before splashing with them.

 

[34109411]

The reality is that DM-led dives in places like Cozumel are going to be reasonably safe with or without a computer as long as you use a little bit of common sense. Common sense mostly means staying about the same depth or shallower than the DM.

If you think about it, the DMs not only want to keep the divers safe, they have to learn to tailor their profiles so that none of the common computers go into deco. The normal deep Coz dive, for example, will only have a few minutes at the deepest part and then a leisurely ascent to somewhere in the 60-70' range for many minutes and then another bunch of time around 30'. Second dives are almost always shallow as are afternoon and night dives. Even outfits like Aldora, which prides itself on the length of its dives, will have a lot of that extra time spent drifting along at the nitrogen loading equivalent of safety stop depth given their high 02 level nitrox mixes.

Even wreck dives in vacation spots are as SurfGF friendly as possible with the DM usually doing a quick lap or half lap at the bottom before moving up to the highest points on the wreck. I'm also convinced that they often they push the speed a bit or expose the group to more current than necessary during the deep part to "help" divers run out of gas before they run out of NDL time.

yes you are right about DM in COZ.

 

[tursiops]

extra time spent drifting along at the nitrogen loading equivalent of safety stop depth

The safety stop depth (nominally 15 ft or 5m) is NOT a function of your gas mix; it is determined by being at about 1.5 ATA so whatever N2 is in your body has a chance to get out without bubbling, and to slow your ascent to the surface. See the original research on safety stops, referenced elsewhere on SB.

 

[boulderjohn]

The solution for that is to let the dive op know you don’t have a computer and communicate that to each DM at the dive brief.

The solution is not diving? I am pretty sure most dive operators won't let you in the water without one (or the equivalent).

I was diving in Cayman Brac quite a few years ago, and a woman emerged from a dive with her husband, and the DM on the boat asked her where her computer was. She said she was just sharing her husband's. Nope. Did he have tables? No. Well, that was it. No diving for her until she came up with a computer.

 

[lowwall]

The safety stop depth (nominally 15 ft or 5m) is NOT a function of your gas mix; it is determined by being at about 1.5 ATA so whatever N2 is in your body has a chance to get out without bubbling, and to slow your ascent to the surface. See the original research on safety stops, referenced elsewhere on SB.

OK, stipulated, (waves hands in surrender.).

But 10-20 minutes at 10m on EAN38 will wash away any sins from small, inadvertent or otherwise, excursions beyond NDL.