Dive #70: The Shores
| Date & Time | 2007-06-30 @ 11:10am |
| Visibility | 10 - 20 ft. |
| Max. Depth | 76 ft. |
| Min. Temp | 59° F |
| Bottom Time | 26 min. |
| EAN32 Info | Al 80: 2660 - 1380 psi = 0.54 ft3/min |
Our first Nitrox dive didn’t go as well as it could have
This was definitely a learning dive.
First, SDUA gave us aluminum 80 tanks. I hate AL 80’s, they end up floaty instead of sinky at the end of the dive. That’s why we have high pressure steel 80’s. They start off sinky and end up less sinky.
But we (Jess and I) did get to analyze them at the shop using an Oxycheq analyzer. Good experience. One of the tanks didn’t have as much O2 in it as we wanted so we got it topped off before we left. Awesomeness #1.
Once we got to The Shores we unloaded all the gear and I spent the next 30 minutes trying to find a parking spot. Not so much fun, but it worked out. We re-tested the tanks before we finished gearing up and saw that there was as much as 0.5 percentage points of difference between Steve’s brand new analyzer and the Oxycheq at SDUA. Interesting, but not significant since we always round up (32.1% → 33%) for safety.
We then neglected to put enough extra weight in our pouches to deal with the aluminum tanks being lighter. Mistake #1.
The swim out was fine, there were 3 - 5 ft. waves that we got lucky timing. Getting our fins on and swimming out was just peachy. Once we were out I had a little trouble sinking, getting all the air out of my dry suit resolved it. Jess had quite a bit of trouble getting the air out of her dry suit and couldn’t sink well at all either. When diving aluminum tanks you should sink like a rock at the begging of a dive. Mistake #2.
Jess had to go back up and I went up with her, being a good buddy. Steve popped up and suggested that we just swim down a bit to get under and we’d be fine. We listened to him. Mistake #3.
Once we were down and swimming with the group we got separated as I was checking out a giant flounder. Mistake #4.
Jess was having a really hard time staying down and I didn’t fully realize when she was trying to show me that she was getting low on air. It wasn’t until we were at 40 ft, going back in that I saw she was down to 650 psi. Mistake #5.
At that point we started going up as slowly as we could, but without enough lead it didn’t really work out and we ended up making that rapid ascent you see at the end of the graph. Nothing we could have done about it #1.
Luckily, because of the extra oxygen in the tank our ascent was from the equivalent of around 30 ft on a 60 ft dive. We didn’t have much nitrogen in us at all.
We made it back all right, we weren’t bent and don’t expect to be. We got really lucky and this was quite the wake up call for us. I think we’ll both be better divers from here on out because of this experience.
Depth Profile:


















