I notice that might be a problem of anxiety, explaining, I run through the first 50 bars, from 200 to 150 very fast, then I start to breath more calmly and air tends to last a bit more.
There’s two opposite ways you can go about this:
One, a larger tank will give you more ‘air’. More air is not likely to give you *less* time, though it will probably give you less time than you think it will, because of the drawbacks that that larger tank brings. But in the grand scheme of things it’s really not going to hurt you to have a larger tank. Of course, buying one is expensive, and they’re very unwieldy — if not downright difficult — dealing with them on land and especially a boat, but it is likely to give you at least a little bit more time.
Two, a larger tank is an equipment solution to a skills problem. Like someone asked, and like you seem to acknowledge in my quote above, are you a new diver? If so, then your problem is not the amount of gas that you bring with you. It’s the amount of gas that you use unnecessarily while you’re there.
The stress and anxiety of being in an unforgiving environment, that is completely foreign to our experience and capabilities on the surface is difficult, and it takes time to be able to master the environment and your mental or emotional state. And gaining mastery over each of those are very closely related.
As many have stated or alluded to, as you gain experience you will gain familiarity, which will lead to comfort and lower gas consumption. But you can do much to accelerate this. First thing I would encourage you to focus on getting your weight correct. I’m not going to bother to outline exactly how to do that: do some searching on scubaboard and you’ll find 1000 posts talking about it. But until your weight is within a couple of pounds of correct, that will directly affect your ability to be consistently stable in the water without propulsion. And if you need propulsion from your legs – or even worse, you’re using your hands – to stay stable in the water, that’s nothing but wasted gas every second of the dive.
A second very closely related thing is: get your propulsion correct. The biggest factor in that: being horizontal in the water. If you are at an angle in the water, every fin kick will push you both forward and *up*. Your upward movement will make you think you are too light — after all, you’re drifting upward! That will cause you to keep yourself overly negative in the water, which means as soon as you stop finning you will drop. That means you can never stop finning. Go back to point number one right above: that causes you to have to waste gas every second of your dive.
Like I said, there’s only 1000 posts out there talking about all of this. But as a new diver, it’s a great deal to have to work on, and unfortunately you kind of have to do it all at once. Give yourself permission: this will take time. And like others have said, if your buddies are impatient with you, you will either need to ignore them or find new buddies. This will take time.
But in the interim, if you have access to a larger scuba tank that can be made to work without too much of a difficulty, there probably isn’t that much of a disadvantage in using it. If I were diving with someone who is a new diver and if there was an aluminum 80 and a steel 100 between the two of us, I would try to put them in the 100 and me and the 80. why not? That helps both of us.
But just know that this will get better. I was someone who was consistently dragging people out of the water on boat dives as well. And I too was looking longingly at a 130 ft.³ tank, thinking I needed that in order to be able to stay down as long as everyone else. But they were so expensive I didn’t actually buy one. And now I’m really glad I didn’t. It is completely unnecessary. Time, experience and additional training got me to the point where I was in the average area for gas consumption, which is just fine with me.
Now, how long did that take? About 100 dives. Unfortunately, I didn’t have mentors that could really help me to really focus on improving my actual diving quality, so it just kind of came along by trial and error and accident. It doesn’t have to take that long. But just know: it will take a while, and Unless you put focused effort into it, it might even be a long while.
But it will come.
