First dive at 40 meters - Newbies recreational

[Graeme Fraser]

Hi Op

Maybe back off NDL and depth limits a bit, but apart from that you seem to be heading in the right direction. I also wouldn't worry too much about perfect 'spirit level' trim and comatose SAC rates at this stage. A lot of this is BS anyway. Your natural Zen will come in time.

Enjoy your diving. I wish I was in Cape Verde right now .

 

[boulderjohn]

That's right. The reason I don't do it if that I am not sure that I will properly control the LPI. I will train someday though. And another thing that I need to study is: in which conditions, will flipping consume more or less air than using the LPI to inflate the BCD?

If you are doing a horizontal ascent, you do not use your low pressure inflator to dump air. You use a butt dump at the bottom of your BCD. When I am doing a typical dive, I use the LPI to dump air for my initial descent, but I rarely use it after that.

The kicking (I assume that is what you mean by "flipping") during ascent should be close to effortless. If you have to work at it, then you have dumped too much air from the BCD.

Some people will initiate their ascent not by kicking but by simply inhaling deeply.

 

[scubadada]

It is literally not possible. If you maintain neutral buoyancy, you will not ascend. You will stay at your current depth. If you are neutrally buoyant, you must do something to begin your ascent. The obvious thing to do is give a light kick to start going upward. As soon as you do that, you will become positively buoyant, and when you feel you are positively buoyant enough that your buoyancy is bringing you to the surface, you must vent air to maintain control. You should be close to neutrally buoyant throughout the ascent, but you are actually going back and forth between negative and positive.

Some instructors (and report area divemasters) go so far as to tell students and divers to dump ALL air from their BCD before they ascend. That will work for divers with thin wetsuits and reasonably good weighting, but it is a bad habit because in cases where diers have extra weight, as with a thick wetsuit, they will become too negative and will sink.

(I have an article on this pending publication through PADI in the next year or so.)

I start my ascent from the bottom with a little kick up. I an horizontal and start up. I continue a little kick up and vent my BC as indicated when my acsent rate increases. With practice, this becomes entirely second nature and results in a very smooth ascent to your stop or SS level.

 

[Dody]

I start my ascent from the bottom with a little kick up. I an horizontal and start up. I continue a little kick up and vent my BC as indicated when my acsent rate increases. With practice, this becomes entirely second nature and results in a very smooth ascent to your stop or SS level.

That’s exactly what I do.

 

[Dody]

If you are doing a horizontal ascent, you do not use your low pressure inflator to dump air. You use a butt dump at the bottom of your BCD. When I am doing a typical dive, I use the LPI to dump air for my initial descent, but I rarely use it after that.

The kicking (I assume that is what you mean by "flipping") during ascent should be close to effortless. If you have to work at it, then you have dumped too much air from the BCD.

Some people will initiate their ascent not by kicking but by simply inhaling deeply.

Sorry. English is not my usual language And I was talking about inflating the BCD to ascend at depth not dumping air which I do anyway. When I kick, I control my ascent 100%. I slow down or accelerate at will. With the BCD it requires more experience.

 

[Blackcrusader]

That's right. The reason I don't do it if that I am not sure that I will properly control the LPI. I will train someday though. And another thing that I need to study is: in which conditions, will flipping consume more or less air than using the LPI to inflate the BCD?

As I wrote before any movement means you breath more. Using the BCD as it's intended you will not have to fin as much my fin use is mainly for direction and less for propulsion cause I am lazy lol.

My BCD is my sofa and magic carpet. I lie down it in or maybe let it carry me in a vertical position especially in a drift dive where being vertical means I get pushed faster than someone who is horizontal. I have passed by people finning as I sit there not moving. They look at me strangely as to why I can go faster than they do it a current without moving. Mainly they are close to the reef wall where the water can be a bit slower and I am further out in faster water. These things you will learn over the course of your dives as not everything can be taught in courses.

 

[boulderjohn]

Sorry. English is not my usual language And I was talking about inflating the BCD to ascend at depth not dumping air which I do anyway. When I kick, I control my ascent 100%. I slow down or accelerate at will. With the BCD it requires more experience.

It's a lot better than my Dutch!

When I was first in the Netherlands, I was amazed at how the Dutch could figure out I was an American at about a block away and speak to me in perfect American English. On that same trip I then went to England and could barely understand a word anyone was saying.

 

[Blackcrusader]

Between 11 l/min and 12 l/min it would probably make no difference. But as the OP's description showed, none of those consumption rates would be appropriate to calculate his reserve. Between a suitable reserve and one calculated with 11 l/min, it could make a huge difference in case of emergency.

This was my point as he pre planned the dive using 15l/min the used 12l/min. So if in a true emergency it could happen you miscalculate your available air. So a 4l/min difference is a lot when you are at 40m depth then x 2 divers on one tank

 

[Blackcrusader]

I meant close no neutrally buoyant. The obvious thing to do is to breath on the top of my lung capacity until I start to ascend.

for myself I will not use 100% of my lung capacity to initiate an ascent. maybe 75%. If I am worried about finning and not stirring up silt in a wreck or in a cave or just on the seabed a little air will give you a slow lift it's not like you need to fill your bcd to capacity either.

 

[boulderjohn]

Sorry. English is not my usual language And I was talking about inflating the BCD to ascend at depth not dumping air which I do anyway. When I kick, I control my ascent 100%. I slow down or accelerate at will. With the BCD it requires more experience.

Okay, I may be misunderstanding your English again.

When you are diving, you should be neutrally buoyant, so that if you were to stop kicking, you would simply hover at that depth. If you want to ascend, a very slick kick sending you upward just a little, or a deep inhalation, should make you ascend a little bit and start the ascent. What happens in the next few seconds depends upon your depth. If you are very deep (say 40 meters), it will not make much difference, so you can continue that very gentle kicking for a while. The gas in your BCD and wetsuit will begin to expand, making you more buoyant, and if you feel that added buoyancy pulling you upward, you will need to dump some air from the BCD. Once again, you should be able to ascend with very gentle kicking. As you get shallower, by Boyle's Law that expansion during the ascent will increase. Your BCD and wetsuit will expand much more quickly in the top half of the ascent than the bottom half, and your buoyancy will change more quickly.

You should never have to add air to the BCD to ascend, either at the beginning of the ascent or at any time later. The only reason you would have to do that is because you were somehow too negative. If it is to start the ascent, then that means you were not neutrally buoyant when you started. If it is later in the ascent, it is because you dumped too much air at some point.

Many and probably most beginning divers are not neutrally buoyant as they dive. They are negatively buoyant and rely on constant kicking to keep themselves at their current depth. You will see them typically swimming at a 45° angle. When you are diving, test this by stopping all kicking to see what happens. Most beginning divers who do this will sink immediately and perhaps rapidly. If you are neutrally buoyant, nothing should happen. You should just hang there like a fish hanging out in a fishbowl.