Recommendations for pony bottle/regulator set up for solo diving

[happy-diver]

So tell me when was the last time you never did that and why would you dive with someone that did

 

[Tigerpaw]

edit: You can also real-world test about how much air you'll need. Dive to the maximum depth you expect to take your pony bottle, lets say 90ft. Swim around enough so you're using air, check your PSI, and then surface normally, including safety stop. Write down the start and end PSI. From there you can calculate how much volume you actually used. Then add some % of air, depending on how prepared you want to be for panic, entanglements, etc.

Thank you for the explanation. Prior to reading your post, I finally settled on a 40 for a pony bottle. I reasoned that it can get me out a jam if I'm deep (130ft.) People were complaining about packing it but mine fits in my suitcase with the rest of my scuba gear.

Oh funny that you mention sidemount, I do my open water portion this coming Monday! So why the pony bottle if I will be able to dive sidemount? I plan to use it when I'm diving backmount.

 

[SlugLife]

Thank you for the explanation. Prior to reading your post, I finally settled on a 40 for a pony bottle. I reasoned that it can get me out a jam if I'm deep (130ft.) People were complaining about packing it but mine fits in my suitcase with the rest of my scuba gear.

If you're willing and able to use bigger, whether that's sidemount or 40cu, I'd definitely encourage that.

Most of the reason to go smaller is weight, convinence, size, and/or laziness.

So why the pony bottle if I will be able to dive sidemount?

For 98% of SideMount divers, just dive SideMount. I'm describing what I do, but not necessarily recommending it.

Essentially, I'm diving a variation of "Monkey Mount" (which is SideMount, but only one side) plus a pony. The reason for this primarily revolves around my personal situation, and the kind of dives I do. My buddy's boat looks a little like this (below) and two divers putting on gear, on the back at the same time, with one sidemount (taking extra width) while nearby boats generate waves can be a giant pain. Similarly, climbing a narrow boat ladder with 2 tanks while being hammered by waves is a good way to get a sore back. I don most of my gear including the pony-tank in the front. Then, when my buddy jumps in, I'll attach my main-cylinder and put on my fins, then jump in.


Two 40cu or 50cu would probably be ideal, but around here, every fill cost $10, so I'd be doubling my fill-costs. Backmount would also probably be more practical, but I enjoy sidemount, and want to keep practicing SM.

If it was my boat, I'd probably just do normal SM every dive. I'd probably pick a boat better for diving than speed. I'd also drop some line and clips over the side, so I could unclip tanks in the water, and then pull them up one at a time. When I do pretty much any other dive (shore-diving, etc), it's almost always regular SM.

If anyone wants to go much further into the topic of offset-size sidemount, here's a thread on it:

Side-mounting 2 different sizes (ex: 80cu & 40cu).

I recently started looking into a redundant air-source, and may suggested side-mounting. Then the idea of side-mounting both my main (80cu) and redundant (19cu or 40cu) came up. This seems like it would be great for the type of diving I do (boat with small ladder). My only question is, does...

scubaboard.com

 

[Tigerpaw]

If you're willing and able to use bigger, whether that's sidemount or 40cu, I'd definitely encourage that.

Most of the reason to go smaller is weight, convinence, size, and/or laziness.

For 98% of SideMount divers, just dive SideMount. I'm describing what I do, but not necessarily recommending it.

Essentially, I'm diving a variation of "Monkey Mount" (which is SideMount, but only one side) plus a pony. The reason for this primarily revolves around my personal situation, and the kind of dives I do.

My reply to "So why the pony bottle if I will be able to dive sidemount?" is in the next sentence of my post. I plan on using the pony bottle for the times I dive deep with back mount.
That being said I like your Monkey mount concept. Just out of curiosity, do you use extra weights to balance out the pony tank?

 

[rx7diver]

... I finally settled on a 40 for a pony bottle. I reasoned that it can get me out a jam if I'm deep (130ft.) ...

@Tigerpaw,

Here is a link (Gas Planning Example) to an old thread that contains an example that details, among other things, how you might determine the minimum size "needed" for a pony bottle (bailout bottle) for a recreational dive.

The example is straightforward, written for a 100 fsw NDL dive. I learned to do a simpler version of this approach to dive planning when I took my open water course (in 1986). You might rework the example, but using a 130 fsw NDL, instead.

rx7diver

 

[SlugLife]

That being said I like your Monkey mount concept. Just out of curiosity, do you use extra weights to balance out the pony tank?

What would be ideal, is to have a weight you could move (slide or clip) towards the left (AL-80 side) as the tank empties, however I haven't gotten around to doing that yet. I've mostly just gotten used to the slight imbalance.

I have added weight to the pony-side when diving with a steel tank.

 

[grantmac]

You don't need offset weight with a single AL80. It's simply not that buoyant.

 

[FishWatcher747]

What would be ideal, is to have a weight you could move (slide or clip) towards the left (AL-80 side) as the tank empties, however I haven't gotten around to doing that yet. I've mostly just gotten used to the slight imbalance.

I am experimenting with offset weight. My configuration is Al 80 backmount with a 19 cuft Al Pony slung on the left. 2 pounds extra on the Right is not enough to offset and 3 pounds is too much.

I test the proper offset by hovering then crossing my ankles in the back and seeing which way I rotate.

So I bought a 1 pound hard weight that I will travel with to my next dive trip. I will attach it to the top of my backplate with parachute cord that can be adjusted sideways on the plate.

I suspect the proper offset is about 2.5 pounds but there is no 0.5 pound weights on dive boats.

 

[inquis]

You don't need offset weight with a single AL80. It's simply not that buoyant.

Huh? A full AL80+1st stage is 3.8 lb negatively buoyant in salt water and 4.7 lb in fresh. Why fight that?

 

[SlugLife]

2 pounds extra on the Right is not enough to offset and 3 pounds is too much.

Use fishing weights, lead from a gun-range, or open up a "soft" weight and remove half, and then sew it closed.

You don't need offset weight with a single AL80. It's simply not that buoyant.

Based on experience diving AL80 & AL19 sidemount:

• At the beginning of the dive, I very slightly to the AL-80 side, but I sometimes don't even notice.
• At the end of the dive, such AL80 at 1000 psi or less, and AL19 with 2800psi, the difference can be quite noticeable. I'm more than used to it by now, but the tank is steadily trying to pull my left side up about 20-degrees.