Got the rebreather back in the Open Water for 2 hour long dives. 1st dive was not so good. Started off fine until a navigational error took us clear across the quarry, furthest from the entry point as you can get. On ascent to get our heading corrected, my undergarment got up into my drysuit's exhaust valve. I could not vent any air out of the suit. With empty wings & nearly empty counterlungs, I still managed to get into an uncontrolled ascent from about 40 0ft. My instructor did what he could to assist me. We made it to the surface safely, but it was rather hairy for a bit. We got our heading & went back to shore with no further issues. After making a few more adjustments, my unit finally trimmed out (I was a bit nose heavy). The second dive went much more smoothly & I was much more comfortable & at ease with what I was doing. I realize now, I have a very long way to go & still have much to learn & perfect, but with time, practice & perseverance, I can make it.