Simple question about removing backup regulator

[mcavana]

99% of the students who do their OW with the shop I DM for leave OW classes PROPERLY weighted for their checkout dives, and with an understanding of how to properly check and modify their weight when diving in other locations/rigs/exposure protection. I can't speak for the quality of training at other shops.

Pat yourself on the back. That is outstanding! Now please define "Properly Weighted" so we can all re-align ourselves to your standards.







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[spectrum]

mcavana,

Based on what you describe in post #60 you may be very close to having the right weight.

If you're making a safety stop at 15 feet with a near empty cylinder and SLOWLY sink with an empty BC you could even be where you want to be. remember that you want to be able to control your ascent all the way to the top. Some of this can be done with lung volume. Being a new diver and probably in new neoprene you probably have a radical swing in buoyancy, especially in the shallows where the percentage of change per foot is high. Dropping 2 pounds at a time is a good way to progress.

If you are shore diving you may even want to end your dive neutral in as little as 6 feet or so. Some dives end with significant time in the shallows and you don't want to be chasing rock to help hold you down.!

The use of anchor lines and other props to stay down at the end of the dive is not what you want to be doing.

Here is another way to get at the answer:

Remember to set your weight so that you bob vertically at eye level at the end of your dive with an empty BC, an average breath, your feet still (crossed) and about 500 PSI in your cylinder. A deep breath should get your mask out of the water and a deep exhale should sink your mask. Do all of this while breathing from your regulator. The end of the dive is the defining moment for your weight requirement and you want just enough to let you stay down in the shallows with a light cylinder.

You can make the same test pre-dive with a full cylinder and add 5 pounds to compensate for the buoyancy gain you will experience as you breathe the tank down. Be sure to repeat at the end since you are apt to have some stowaway buoyancy (trapped air) in your gear early in the dive. You are safer being two pounds heavy than 2 pounds light.

Pete

 

[LeadTurn_SD]

1+ what Pete said.

If you are just sinking "ever so slowly" at the safety stop with 500 lbs and an empty BC (make sure it REALLY is empty), you are very close to target weighting. If you have to fin or add air at the safety stop, you are too heavy. If you are having trouble staying down, too light. Most of us call it "close enough" at about the weighting you describe, give or take a couple pounds, because you can easily compensate for a couple pounds just with lung volume.

Good luck and Best wishes.

 

[Slonda828]

I almost didn't post this, but I feel obligated to do so. For the record, I advocate the 30 or 40 cubic foot pony, and I think spare air is crap. I know at this point in the thread that we are past spare air. My main concern is the fervent, almost blind belief in the alternate second stage.

There is only one o-ring (-011) on a 3/8" port plug. That is a fact. Stay with me, this is going somewhere.

There is also an o-ring on the first stage side of a low pressure hose (-011 again), and another where the second stage hose meets the orifice (-010). There is typically at least one where the orifice mates to the second stage housing (-014 typically). There is a soft seat where the poppet is on a downstream second stage. Then, there is the diaphragm and mouthpiece, and a zip tie. Those are 7 potential failure points. I am being generous as most second stages these days are balanced, so they have many more (especially if the have an end user adjustable cracking pressure, venturi, etc). So you are adding 6 more (minimum) soft failure points every single time you add an alternate second stage to your gear. Normally, this is preferable because most people have no idea how to buddy breathe, or because it is PADI standard in some of my dives, or because it is how you have been taught. Normally, I dive with an alternate as well. Again, stay with me.

Everyone rails on about how diving with only one second stage is heresy. Why? If I have a 30 or 40 cubic foot pony bottle with a first and second stage, then a first and second stage on my back gas, why do I need one? Even PADI safe diving practices say that you need an alternate, safe second, OR redundant SCUBA. A pony with its own first and second stage meets this requirement. In my opinion there is zero need for an alternate second stage on your primary first stage if you have a pony bottle of appropriate size for the depth and planned profile.

It just blows my mind how people just leap onto their keyboards when someone merely mentions diving with only one second stage. When I dive vintage gear I only use one second stage (because you can typically only use one), and we plan our gas and practice buddy breathing. I understand that most people do not dive vintage, but the skills are still valuable.

There are times when diving with only one first and second stage is fine. If you are trained and willing to practice the skill of buddy breathing, it is not the end of the world. Last weekend I dove the jetties with my girlfriend. We both dove vintage regulators and we planned out our gas. Neither one of us had alternate second stages (no place to mount them). If you stay close to your buddy, and dive your plan, then what is the huge issue? I am not saying that everyone should dive with just one second stage, but there are situations where it is perfectly fine. Would I dive 100 foot profiles with no pony bottle and one second stage? Nope. Still, on shallow dives, river dives, or numerous other types of dives, having only one second stage is preferable in some cases.

I just do not want people to think that the freaking world will end if they take off their octo. I know 90% of the time it is a good idea to carry it, but there are other times.

 

[rjack321]

It seams easy enough! just wanted to know if you more experienced equipment guys have anything more to tell me on this subject.

Practice once from 60-80ft with the spare air. You'll find 3cf is uselessly small. Try not to embolize when you suck it dry halfway to the surface.

Get yourself a decent sized reserve, doubles or pony. Maybe take one of the "solo diver" courses to help you become more self sufficient. They you can make an educated judgment on your own.

 

[LeadTurn_SD]

.... I just do not want people to think that the freaking world will end if they take off their octo. I know 90% of the time it is a good idea to carry it, but there are other times.

Two thumbs up

Boy this thread went sideways over a simple initial question, just because of a few simple words... (I bet mcavana will NEVER mention the words "Spare" and "Air" in the same sentence again ).

I never owned an octo (or BC, or computer) until two years ago We were all trained to buddy breath when I learned to dive.

I do mostly buddy dive these days, but maybe 10-20 times a year will solo. So I just use the same rig I buddy dive with. I see the points about additional failure points, but (since I dive classic downstream, non-adjustable 2nd's) don't see this as enough of a "threat" to safety when soloing to remove my backup reg. Then again, I'm about the laziest guy you'll ever meet, so that could have something to do with it

Best wishes.

 

[Jorgy]

You make some great points...........

But this thread did not start as - I dive with a 30 or 40 CF pony and want to remove my octo..........it was a 3 CF Spare air............

With a that large of a pony your are practically at independent doubles status..........and that is an entirely different scenario......

Just my thoughts..........M

 

[Slonda828]

You make some great points...........

But this thread did not start as - I dive with a 30 or 40 CF pony and want to remove my octo..........it was a 3 CF Spare air............

With a that large of a pony your are practically at independent doubles status..........and that is an entirely different scenario......

Just my thoughts..........M

Jorgy,

I agree with you.

 

[mcavana]

This is the most educational thread of all times! You guys rock!

Slonda, and everyone else. Please allow me to get back to my original question in the title of this post without any attacks or flames.

If I am solo diving in 80 to 100 feet.... I have my 80cf aluminum tank as my primary air source. I have a 19 cf pony bottle slung under my arm with its own 1st and 2nd stage for emergency use only. The pony bottle, because it is only for emergency use will always be full. I am spearfishing. I plan to get one good fish and head up. at 80 feet I will head up with at least 750 psi left in my main tank (having not used my pony bottle at all) and at 100 feet I head up with at least 1000 psi left (having not used my pony bottle at all).

In what I just described, would it be ok for me to remove my octo (backup 2nd stage on my primary air source?)

To head off questions before they come up... why would I want to? That is simple. one less thing to worry about. One less regulator to go into freeflow mode. One less thing to be in the way.

If the general consensus is that I can remove the octo, can I use that second stage for my pony setup to save a couple bucks possibly?

Sincere thanks to everyone involved in this conversation. Who knows, you may have already saved my life. (you probably did in regards to the dreaded spair air!)

 

[Slonda828]

MC,

In the situation you just described I would dive with only one second stage on my primary first stage regulator. That is just my opinion. PADI and several other organizations support this, as you are now considered to have a fully redundant SCUBA unit with you. I have also seen several other people dive configured in this fashion. You know what opinions are like though!

Also, I would personally opt for a 40 cubic foot tank. This is just my opinion, but then later you are already used to diving with a 40 CF tank slung, which is pretty much the size of all stage bottles (unless you are VERY serious and sling 80s). I have never slung 80s, but then again I am not a caver or mix diver. Also, if you already have a 40 CF tank for a pony, then you do not need to purchase one later when you need a stage bottle.