Notifying the team

Here's a real scenario (and before you have at it, yes, I know I screwed up and it's been pretty extensively debriefed and discussed. The question is how to manage the error, not whether it should have been made or not):

Four divers prepare to do an uncomplicated recreational dive. They will dive as two buddy teams but intend to stay together. One diver will lead, and his buddy is a novice. The other two are experienced divers. The leader and second team are diving HP130s. The novice diver has an HP100. Max depth of the dive is 60 feet, and proposed dive time is 50 to 60 minutes, most of which will be spent in the 40 foot range. The diver who screwed up has a SAC rate of .35 to .4 on this type of dive, and is part of the second buddy team.

At the first underwater gas check, one diver discovers her 130 wasn't full when she grabbed it, and she hadn't actually checked the pressure before diving. (Yes, it's a BIG mistake.) But a quick mental run-through shows that she has plenty of gas for the proposed dive and to maintain rock bottom for the 60 foot depth.

The question is: Does this diver attempt to communicate to the leader that she has less gas than he thinks she has? And if so, how would you go about doing this?

It's a 60ft pleasure dive, no deco, nothing serious IMO. I would not waste dive time telling my buddy that I'm not completely full as long as it's within agreed upon safety margins. My logic is that no matter how much gas I start with, I still need to surface at the predetermined rock bottom, so why waste it trying to explain I grabbed a tank that wasn't full?

Now, if there were a full tank on the boat, I would signal to surface and swap it. But IMO a 20min dive is better than a 15 minute dive + 5 minutes of confusion, even if 1 hour was the ideal time.

slate /or let low gas turn the dive

As I see it its the bullet points are:

• My god. Its an uncomplicated recreational dive. Who cares??
• You have enough gas to complete the dive so who cares???
• You have two buddy teams so you can split up and let the other team complete their dive if you run low so who cares????
• If you run low, your buddy has a 130 so share some air with him/her so who cares?????

Thumb the dive.

You don't know what's in that tank with old analysis tape on it. Was X pressure, O2 was added to make 32% or even He was added to make 25/25 but it wasn't topped off with air = something not good.

Personally I think you are focusing way too much on the fact that your volume was less than anticipated (but still adequate for the profile - so I agree no big deal) when the real issue is that you had no idea what you were breathing.

If you have enough gas to a) complete the dive while b) maintaining your min gas reserve, then I would say you brought enough gas for the dive, and it doesn't matter. At all.

The bigger point here is that said diver and said diver's team missed out on a reasonably important pre-dive check. Did said diver also analyze the gas in that tank?

i would just do the dive and not worry about it probably.

The reason I brought the question up here was that the team leader was not happy that I hadn't informed him of the change in status. I didn't think it was necessary, and it sounds as though most of you don't think so, either.

The rest of the issues with the dive, as I said, have already been discussed and I've taken the lessons to heart.

Turn the dive at rock bottom pressure ... goodness, Lynne ... the way you breathe that'd only have given you about a 90-minute dive ...

... but I agree with Richard that the lack of analysis would've made me more nervous than the fact that the tank was only half full ...

... Bob (Grateful Diver)

yea, my answer assumes the tank was analyzed.
was it analyzed?