Non-technical dive-planning software?

[jeckyll]

rstofer: Actually yes, it is taught that way by some
And as boulderjohn pointed out, not all tissues are equal, so no, on the ascent not every minute at 'depth' you'll be ongassing. It all depends on which tissues. As far as my understanding goes anyways

boulderjohn: I usually spend more than an hour between dives. I quite like Peter Steinhoff's tables actually. I think the problem is that many would not have the ability to hold those stops effectively.

daniel1948: A (large?) number of people believe that your last 20 feet should be your absolute slowest ascent. Based on my own experience, I know that feel much less tired if I take it real nice and easy of the last part of the ascent.

 

[boulderjohn]

May I ask what rate you advocate for that last 15 feet? I had an experienced diver tell me I was ascending too fast after the safety stop, although I am confident I was well within the PADI-recommended 60 ft/min, which was all I knew at the time.

The last 15 feet are, contrary to popular belief, the most dangerous. That is where you have the greatest effect of pressure change. I don't actually ever say a rate, I just use this word: crawl. When I am with a group and we decide that it is time to go to the surface, I am lying face down and horizontal. I inhale a little to start the process, and then a little more, etc. until I gently drift to the surface. I really don't know what that rate is. It takes me anywhere from minute or even more.

 

[jeckyll]

The last 15 feet are, contrary to popular belief, the most dangerous. That is where you have the greatest effect of pressure change. I don't actually ever say a rate, I just use this word: crawl. When I am with a group and we decide that it is time to go to the surface, I am lying face down and horizontal. I inhale a little to start the process, and then a little more, etc. until I gently drift to the surface. I really don't know what that rate is. It takes me anywhere from minute or even more.

Just to add to that, whenever possible I take some time and just float or very slowly swim, on the surface as well. On protected shore dives, generally about 5 minutes. Then I start to make my way out of the water. Again, more time to offgass

 

[daniel1948]

Just to add to that, whenever possible I take some time and just float or very slowly swim, on the surface as well. On protected shore dives, generally about 5 minutes. Then I start to make my way out of the water. Again, more time to offgass

I understand taking the last 15 or 20 feet very slowly, due to the relative pressure change. I do not understand spending time floating before getting out, since at that point you are breathing air at 1 ata. (Though my dives up to now have been drift dives from a boat and I usually end up waiting on the surface for 5 to 15 minutes with my buddy or group until the boat arrives. -- I don't know whether this next trip we'll be going down and up directly from/to the boat, or taking a tender and waiting for it after surfacing.)

 

[Kevrumbo]

I understand taking the last 15 or 20 feet very slowly, due to the relative pressure change. I do not understand spending time floating before getting out, since at that point you are breathing air at 1 ata. (Though my dives up to now have been drift dives from a boat and I usually end up waiting on the surface for 5 to 15 minutes with my buddy or group until the boat arrives. -- I don't know whether this next trip we'll be going down and up directly from/to the boat, or taking a tender and waiting for it after surfacing.)

Asymptomatic bubbles; you don't want any of these potentially "shunting over" with any post-dive exertion or exercise.

 

[jeckyll]

Daniel: Toe expand on what Kevrumbo linked to, you have to appreciate that your decompressing after every dive.

You can decompress in the water or out of the water. For much 'recreational' diving, people decompress out of the water. Some computer show this as some sort of nitrogen or load indicator, but the long and short of it is I like to give myself plenty of chance to offgass, both in and out of the water. Just because you could ascend directly to the surface after a 'recreational' dive, doesn't mean that is the lowest risk way of proceeding.

At the end of the day, it's all about reducing the probability of DCS. Hydration, rest, slow ascents, they are all part of it. I also like to do some light cardio the day before diving (it's supposed to flush microbubbles out of your system). Could it all be overkill. Sure. Is it bad for you? Not according to what I've read and the research I've done.

And most important, when I first started diving, I'd feel tired after my dives. Not much, but it was noticeable. Once I've start slowing my ascents and taking some time after the dive, I simply felt better.

YMMV

 

[bleeb]

I understand taking the last 15 or 20 feet very slowly, due to the relative pressure change. I do not understand spending time floating before getting out, since at that point you are breathing air at 1 ata.

A common recommendations is to try to avoid exerting yourself immediately after diving, since strong muscular effort can increase bubbling. In the first five or ten minutes back on the surface you off-gas the most nitrogen, so the idea behind the suggestion is to let breathe a bit first before you go through the effort of hauling yourself and fifty or a hundred pounds of weight out of the water.

 

[daniel1948]

Asymptomatic bubbles; you don't want any of these potentially "shunting over" with any post-dive exertion or exercise.

I understand the need to ascend slowly to discourage the formation of bubbles, and that microbubbles form regardless. I have read other references to asymptomatic ("silent") bubbles especially in the context of free diving after scuba diving (a big no-no). I've also read that exercise is a good thing, both as a lifestyle issue (better cardiovascular fitness reduces your chances of DCS) and after diving (increased circulation promotes off-gassing).

Also, again in the context of free diving after scuba, I've heard of "shunting over."

What I am still confused about is how the very slight exertion of climbing out of the water would promote shunting over. I was actually contemplating doing some surface swimming while on this trip, as two weeks without cardio exercise is a long time for me (I am an exercise addict), and although this would only be a half an hour 3 to 5 times a week, I figured the exercise, when I do it, would help with off-gassing and be a good thing all around.

I've never done more than 2 dives a day before, but have never felt fatigue after a dive. However on this trip they say we'll have the option of 4 to 5 dives per day. The latter probably assumes a night dive, and I'm always tired at night, so I'll probably only make 2 or 3 night dives in the two weeks. Maybe only one if I find I don't like it. I am approaching the idea of night diving with some trepidation and will do my first with an instructor as one elective in my AOW course. So I'll probably be making 3 or 4 dives a day. I may substitute some snorkeling for my first dive of the day, since what I've read suggests that free diving before scuba diving is permissible.

 

[Gombessa]

I've also read that exercise is a good thing, both as a lifestyle issue (better cardiovascular fitness reduces your chances of DCS) and after diving (increased circulation promotes off-gassing).

What I am still confused about is how the very slight exertion of climbing out of the water would promote shunting over.

I haven't heard any recommendations for exercise after a dive. In fact, everything I can remember has suggested otherwise: exercise BEFORE your dive, NOT AFTER.

I can't tell you the specific mechanism for shunting, but if some PFO tests will have you valsalva while they pass bubbles through your blood. The increased pressure from bearing down (similar to physical exertion in exercise) promotes any shunting that may occur.

In general, if you need your exercise hit, consider waking up early and going for a swim before the day's dives.

 

[bleeb]

I've also read that exercise is a good thing, both as a lifestyle issue (better cardiovascular fitness reduces your chances of DCS) and after diving (increased circulation promotes off-gassing).

What I am still confused about is how the very slight exertion of climbing out of the water would promote shunting over.

I haven't heard any recommendations for exercise after a dive. In fact, everything I can remember has suggested otherwise: exercise BEFORE your dive, NOT AFTER.

...

In general, if you need your exercise hit, consider waking up early and going for a swim before the day's dives.

Although I've seen this 'exercise after diving promotes off-gassing' statement before, from all that I've read, it looks like the majority opinion is this not actually a good idea, FWIW. Staying warm so that circulation remains good is probably wise, but making more bubbles probably isn't.

DAN recommends waiting at least a couple of hours for most of the nitrogen to blow off first, before exercising:
Divers Alert Network: Exercise and DCS