Solo diving

[Littlerayray]

I would stick with rule of thirds regardless what size might I add to start your dive in the current stand return with the current

 

[Scubis]

Hello everyone,
I have a few questions for the professionals out there.
1)What's your take on the size of pony bottle for solo diving? 19 cu ft vs 30 cu ft.
2)I am going to use LP 130 cu ft steel cylinder, and if I will follow the rule of thirds, it will leave me with 43 cu ft of air for my assent. On the other hand, when I'm diving AL 80, I will have 26 cu ft left using the same rule. Can I leave 26 cu ft instead of 43 cu ft for my assent when diving steel 130?
3)I am currently using scubapro knighthawk bcd with air 2 as octo and my setup is scubapro mk20/s600. I want to add scubapro R190 as second octo so I can use my other BCD. Was wondering if R190 will serve as octopus.
4)I have another set of regs(Tusa RS-350)that I want to use for my pony bottle. The problem with TUSA that it is not serviced by my diving shop. I can by used Oceanic alpha 8 with dx4 for $90 and service it at my shop. What's your take on TUSA RS-350 vs Oceanic Alpha8/DX4?

1) I would use the 30cuft pony. It might be overkill for a lot of dives. As a solo diver i dont get risky, but more security is better than less. and for your size, a 30cuft pony wont bother you at all when properly adjusted.
2)not sure what you're asking. Typically we measure the rule of thirds in psi/bar, rather than cu.ft. of the tank. So regardless of the size of the tank you can determine a third of your air consumption according to your spg. For example your lp steel 130 is probably 2500ish psi. So youd head out at 2500ish psi, turn back at 1600ish, begin ascent and stops at 800ish psi. Hope that helps.
3) yes the r190 will work as an octo. If you are pulling it from another reg, make sure you do a few test dives with it to make sure it's jiving with your first stage (not overtuned/stiff or undertuned/leaking) if its either of those things you'll have to have a tech either tune it or rebuild it to work off your first stage.
4) Fact. dx4 is a better performer. Oponion. Oceanic regs are more robust and will last longer than a tusa reg. Fact. Oceanic regs are more expensive to than tusa. Fact. your LDS doesnt service tusa.
Bottom line: it's a bailout bottle so there doesnt need to be a super high performance reg attached to it. But it does need to work when you need it. So you want to be able to service the reg.

I hope that made sense! =)

 

[Scubis]

Also, if you are going to use the mk20 on another BCD, keep in mind that you may need to add or switch out the LP Inflator Hose. The male end of the air2 differs from standard BCD power inflators. So your current set up will only work with another BCD that has an air2.

 

[lowviz]

...//... I am thinking to do solo shore dives in Torrance California to improve my trim and buoyancy. ...

I'll be the last person to tell you not to dive solo, but post #10 concerns me. BTDT.

Don't dive solo until you are ready. You should have no problem (where you are geographically) in getting someone to help get you squared away with gear and local conditions.

 

[Kaveman]

I do have a two LP hoses. One is for the air 2 and other one for regular inflator. It is thrue that rule of thirds is measured in PSI or BAR, but mathematically speakin PSI can be converted into cu ft and this is what you breath, at the end of the day, cu ft of air. And the reason that I was asking this question, is how come that when you have 80 cu ft tank, 26 cu ft is enough for assent, but if you diving with 130 cu ft tank, 26 cu ft is not? Just a thought. It doesn't make since to me. Depth on the other hand should determine how much air is needed for assent. I absolutely agree that is better come up with extra air in you tank then with no air at all. I was just curious how 80 will be compared to 130 in this matter.
Thank you

 

[swimlikethefish]

There are a few different methods that I believe you are mixing up:

Method #1, rule of thirds. 1/3 is used descending and swimming outwards. The next third is used to return to the anchor line. The last third is used to ascend and do a safety stop.

Method #2, minimum gas. You would plan your dive depth and duration. Using your sac and rmv. Then determine how much air you plan to use. Annotate your turn pressures. All while building in a safety margin.

You are correct in stating that 1/3 of an AL80 is less gas than 1/3 of an LP130. They are two different tanks, with two different volumes of air. They also weigh different amounts. You would 9nly swing about 6 lbs from full to empty on an 80. While a 130 will swing about 9 or 10 lbs.
Two totally different systems. If I were in your shoes I would plan to surface with no less than 700psi in either tank. This would deem sufficient for your shore diving.

Try to stay with basing gas usage off of pressure not volume. Volume calculations come in later in diving if you wanted to go technical. Not that it's bad, but why complicate something that's as easy as looking at a Guage.

*side note: while not impossible, it is difficult to exceed NDL on an AL80. That is not the case with a 130. Make sure to watch your bottom times as you might find yourself in a situation where you run out of time before you run low on air.

 

[swimlikethefish]

Just some food for thought as well:
Being in such a diverse diving climate it would be so easy to reach out and find a local dive buddy. But, should you chose to not heed the warnings that multiple people have stated you might find yourself in a precarious situation, lacking the fundamental skills to subjugate the risks.
Now I'm not saying by going for a solo beach dive in 20ft of water will kill you. But what I am saying is people have been seriously injured and/or killed doing things a lot less risky. At the end of the day there are no scuba police, just yourself and your mindfulness. Carrying a supplemental air source is the first step. I just want to be clear in stating that training goes a long way in helping you manage risks and react to problems before they occur, not while it is occurring. You didn't just walk into the motor vehicle department and get a license. You got a permit first and practiced with a partner, then tested for the license to operate solo.

Please do not take this as a personal flame towards you, I just want to make it clear for anyone whom stumbles upon this down the road. There is no one to stop you from making your decision after you have weighed the risks.

As always, dive safe.

 

[Kaveman]

Thank you swimlikeafish.

 

[Scubis]

I do have a two LP hoses. One is for the air 2 and other one for regular inflator. It is thrue that rule of thirds is measured in PSI or BAR, but mathematically speakin PSI can be converted into cu ft and this is what you breath, at the end of the day, cu ft of air. And the reason that I was asking this question, is how come that when you have 80 cu ft tank, 26 cu ft is enough for assent, but if you diving with 130 cu ft tank, 26 cu ft is not? Just a thought. It doesn't make since to me. Depth on the other hand should determine how much air is needed for assent. I absolutely agree that is better come up with extra air in you tank then with no air at all. I was just curious how 80 will be compared to 130 in this matter.
Thank you

You are absolutely correct. Your ascent time is almost entirely dependent on your depth and time at depth. The rule of thirds is for general safety. Following the rule of thirds makes it very likely that you surface with plenty of gas and within your limits. Using a single cylinder, it is unlikely that you will exceed your NDL on a single dive without first running out of air. The rule of thirds is an added safety on top of that because in theory, it would be really difficult to exceed your NDL on 2/3 of a tank within recreational limits. I personally dont use the rule of thirds because i feel that i have way too much unused gas upon reaching the surface. Especially if you are carrying a pony on top of that. I like to exit the water with somewhere around 300 psi to feel like I maximized my $6 fill haha. This of course is condition dependent. in very low visibility or rough entry/exit, I like to have a little bit more gas for my exit just in case have to deal with other issues like waiting on a line for other divers to exit, really choppy water where i need to keep my reg in at the surface, or just in case i need a little extra time to find my exit point/anchor line in low vis.

i should note that everything I'm saying is me assuming you are doing recreational stuff. None of the above is valid in the realm of tec or decompression dives that require longer ascent times or deco stops.

 

[scubadada]

I wish people would quit saying you will not approach your NDL, but will run out of gas on a single cylinder dive. This is absolutely not true diving an AL80, let alone a larger cylinder.