3 or 5 minute Safety Stop?

[Atom]

No, the scenario would be: her "high SAC" dive bud experiencing a catastrophic gas loss at the worst part of the dive. Now you have two divers on a partially used sixty-some cuft tank.

If they follow rock bottom it doesn't matter they get up when the first diver reaches the minimum reserve to get both divers to the surface on his tank. Of course that could come quickly on a small tank and reduce the usefulness of the small tank (that has been mentioned many times on SB). Although I have the feeling you know that already...

On somewhat the same topic, I carry rock bottom tables and psi to cuft tables for different size tanks in my wetnotes so it's easier to do correct gas planning with mismatched tanks. Anybody does that or I'm the only one who has problems calculating those in the water?

 

[lowviz]

There seems to be movement towards splitting this topic off as a new thread rather than hijacking tracydr's OP. I'm going to wait a bit on answering you if that is OK...

 

[John_B]

Is this DIR?

No. Why? Does that matter to you?

 

[uncfnp]

No. Why? Does that matter to you?

Just trying to understand his point. Why? Does that bother you?

---------- Post added July 15th, 2013 at 09:37 AM ----------

To avoid hijacking Tracydr's OP, I have started a new thread for anyone interested in continuing the discussion on RB and mismatched buddy pairs...

http://www.scubaboard.com/forums/ba...atched-sac-rates-rock-bottom.html#post6815907

 

[John_B]

Just trying to understand his point. Why? Does that bother you?

Sorry, not trying to be snarky. If it wasn't a DIR dive it wouldn't matter, and it if was the stops would already be known and agreed upon. That said, there is no 3 minute safety stop for a rec DIR dive, depending on the dive plan (depth and time) it's more likely 1 min at 30 ft, 1 min at 20 ft, and 1 min at 10 feet, so there's no way to extend a 3 minute stop that doesn't exist. That's why I asked.

FWIW, when I broached a very similar question with JoeT and Andrew years back about the ascent rate, their answer was to do the stops but do not hang around at depths needlessly where your team mates wouldn't be expecting you to be and that your gas plan doesn't account for, but ascending the final 10 feet as slowly as possible was fine given decent conditions, team eye contact, etc. Which IMO kind of echos Lamont's response that you don't spend extra time at depth needlessly where something could go wrong, even on a rec dive.

Short answer: Dive the plan that the team planned to dive.

 

[tracydr]

The issue is so 100% of the way people dive here....I really could not have imagined ANYONE not using nitrox that was doing charter boat dives. The only people we see using air, are rank beginners on very shallow sites...or on air at the BHB Marine Park with a depth range between 6 feet and 19 feet deep....

Sorry, I should not have made that assumption....
However, the one time I did dive Catalina, on the Great Escape, George and I used Nitrox, and I think pretty much all the others did too

Truth Aquatics boats, which are three of the main boats that dive the Channel Islands, don't have nitrox. I know its hard to believe but that's all they have.
And, the Catalina Dive Park fills are only air, unless you lug your tanks from town or dive off a boat. But, who dives the park off a boat?

---------- Post added July 15th, 2013 at 09:03 AM ----------

There seems to be movement towards splitting this topic off as a new thread rather than hijacking tracydr's OP. I'm going to wait a bit on answering you if that is OK...

I'm finding both topics fascinating.

 

[danvolker]

Truth Aquatics boats, which are three of the main boats that dive the Channel Islands, don't have nitrox. I know its hard to believe but that's all they have.
And, the Catalina Dive Park fills are only air, unless you lug your tanks from town or dive off a boat. But, who dives the park off a boat?

---------- Post added July 15th, 2013 at 09:03 AM ----------


I'm finding both topics fascinating.

Then either the local divers are used to doing shore based dives where no 2nd dive exists, or where it is many hours of interval break from the first dive.....and they are used to diving so shallow that Nitrox is of no value....
Or, this is an area with a lot of cheapskates that would rather dive a little, cheaply......rather than a high volume of really awesome for the cost of Nitrox. Considering the high cost of living on Ca, this 2nd option makes no sense at all to me.
I am not really sure how things could possibly be SO VERY DIFFERENT between diving Catalina and diving Palm Beach and Lauderdale.

 

[diverrex]

Then either the local divers are used to doing shore based dives where no 2nd dive exists, or where it is many hours of interval break from the first dive.....and they are used to diving so shallow that Nitrox is of no value....
Or, this is an area with a lot of cheapskates that would rather dive a little, cheaply......rather than a high volume of really awesome for the cost of Nitrox. Considering the high cost of living on Ca, this 2nd option makes no sense at all to me.
I am not really sure how things could possibly be SO VERY DIFFERENT between diving Catalina and diving Palm Beach and Lauderdale.

The difference between Catalina diving and Palm Beach diving is easy, dives at Catalina are typically much shallower. BTW the Great Escape does not fill Nitrox, you can take your tank filled with Nitrox, you can even take multiple tanks of Nitrox, but you won't get Nitrox fills from the boat. Most dives off the Great Escape are less than 60' with many of the kelp dives in only 30-45'. I remember a day of four dives off the Great Escape where the three surface intervals were only 45 minutes but all the dives were shallow. It has nothing to do with cheap divers just that the boat does not pump Nitrox and the dives are shallow.

 

[chrpai]

There is a tendency to think if someone doesn't spend top dollar for every piece of equipment, training and consumables that they are cheap and that they are going to die.....

 

[DMDavid]

There is a tendency to think if someone doesn't spend top dollar for every piece of equipment, training and consumables that they are cheap and that they are going to die.....

Yes this is true!
Cheap gear = DEATH
Cheap training = DEATH

As for consumables I assume you mean hotdogs instead of lobster which also = DEATH