Pffff.... we are trained to stop our breath for at least 15 minutes while rescuing our buddies using only one hand and taking pictures of the surrounding environment for documentation purposes!
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Pffff.... we are trained to stop our breath for at least 15 minutes while rescuing our buddies using only one hand and taking pictures of the surrounding environment for documentation purposes!
or do you plan for one diver to ascend using that procedure, knowing that if ****happens, using your brain will tell you that you still have oodles of gas--much more than is necessary solve that emergency with a direct ascent?
Remember the 10 ft/min ascent rate is only for calculating MINGAS, not actually for ascending, which is 30 ft/min up to some depth, then and only then slowing.
This thread was specifically about recreational diving, and the hallmark of recreational diving is that you can make a direct ascent to the surface. The time required to get to your next deco gas is not relevant.@tursiops, see @Ayisha's next post, that's the correct answer. [post edited because I misread what you wrote when I first answered ]
Hi @boulderjohn, I didn't really get what you mean here:
In general, I plan my dive with gas enough for two divers to reach the next source of breathable gas (it can be the deco-bottle in tec dives or the surface in rec dives). Bear in mind that some procedures (especially for rec-diving) are not fresh anymore, so I might be making some mistakes here. I know I should have a look again at my fundies material, but I don't find the time now
P.S. a direct ascent, for you, is just an ascent at a constant speed to the surface, without stops, right?
The point is not the actual GUE ascent procedure. It is the silliness of calculating MinGas at 10 ft/min, over the entire depth? What is the point of doing that if it is never used. In fact specifically disregarded, in the lower half of the dive?The 10 ft/min ascent rate is actually used for ascending from half max depth (for a 100 foot or less dive), not just for calculating MG. In practice, it's a slow and smooth slide from stop to stop.
I think what gets conflated here is that a MG calculation works for many emergency situations, but it by no means covers all scenarios. If we reserved enough gas for every potential issue, there would be little or no bottom time.
Using a MG calculation and practicing the corresponding ascent rates just gives the team a healthy amount of gas to work with and the skills to slow the ascent down in an emergency, if they are able to. If gas reserves are depleting and/or the victim is overwhelmed/panicking, you do what you have to do.
IOW, a MG calculation and an appropriate ascent profile is practiced to help achieve the best outcomes in an emergency, but not every potential emergency situation will be covered - by design.
I do not use the speed of 10ft/min over the entire depth. As you said, it wouldn't make sense. I use the actual speed I need (30ft/min for the first half and 10ft/min for the second half). If I want to increase safety, I can use an increased gas consumption to calculate the minimum gas (the gas consumption must be the one of the weaker diver, appropriately augmented to take into account the stress). This procedure affects the calculation less than using a 10ft/min speed for the entire depth.The point is not the actual GUE ascent procedure. It is the silliness of calculating MinGas at 10 ft/min, over the entire depth? What is the point of doing that if it is never used. In fact specifically disregarded, in the lower half of the dive?
You're right; I mentioned the deco bottle to explain the reasoning behind it, but I agree it is better to stick to the topic.This thread was specifically about recreational diving, and the hallmark of recreational diving is that you can make a direct ascent to the surface. The time required to get to your next deco gas is not relevant.
Ok, got it; then yes, I calculate minimum gas in a way such that a direct ascent for two divers sharing gas is safe and possible.A direct ascent to the surface means ascending at a safe speed with no stops. In NDL diving, that should always be possible; it is, in fact, the true definition of NDL diving. A safety stop should be exactly what the name implies--a brief stop in the 15 foot region just to be sure you have not ascended too fast.
The point is not the actual GUE ascent procedure. It is the silliness of calculating MinGas at 10 ft/min, over the entire depth? What is the point of doing that if it is never used. In fact specifically disregarded, in the lower half of the dive?
You mean the OP does not calculate MG correctly?That is NOT how MG is calculated. It's 30 ft/m to half of a max 100 ft depth, THEN 10 ft/m to the surface.
You mean the OP does not calculate MG correctly?