Sidemounts versus Twin Tanks On The Back

[Celt]

ha ha ah ha ha

View attachment 782035

two reg sets, who needs all that extra crap

Nice setup, my Poseidons with reserve, great when you need extra gas.

 

[halocline]

Most of my dives will be off a commercial boat and warm tropical waters. In other words, I'll be using rental tanks.

You might have a hard time using doubles in that scenario. You'd have to rent 2 sets of doubles and then convince the dive op to let you use a technical dive configuration on a recreational charter where the other divers are all in single tanks. Many will not allow that.

Probably the best next step for you is to just use a larger single tank. You can get HP120s at some tropical locations, and those are pretty commonly used for air hogs on Cozumel trips. Try it, it might solve your problem. Diving with two tanks, either BM or SM, presents extra complications on a small recreational dive boat. There's a reason people generally don't do it.

Unless you're a huge person, there is probably some non-gear related reason why you are using much more air than other divers on your trips, if that is what you are describing. I haven't read all the comments in this thread so I might have missed something.

If you are married to the idea of two tanks on a small recreational dive boat and you have experience with BM doubles, that's what makes the most sense. To do SM really well is a process. There are many terrible SM divers out there. (present company excluded, of course!)

 

[rddvet]

Go bm doubles. You can dive more places in bm due to boats not wanting to deal with sm divers commonly. Add to that a place like Bonaire if you wanted more dive time, entry with doubles is easier than dragging two sm tanks. I actually have more time in sm than I do bm but bm is the better choice for you right now in my opinion. Sm has become this thing everybody is doing at any skill level. It’s really meant to be a specialized setup for certain dives at a technical level. But the cool factor has brought it mainstream. Not necessarily for the better.

 

[MightyDuck]

Did you considered mono cylinder on your back and a stage on your side?
This way you have flexibility if only one tanks is required for a shallow dive, easier on your back (you can put your stage in the water without equipment on your back on shore and on boat too), and you can even donate if an emergency would emerge.
And this setup is quite flexible with rented tanks too which usually could cause troubles with doubles.

I would assume you have experience with stages so this way you do not go on a new learning curve.

 

[happy-diver]

But the cool factor has brought it mainstream.

 

[billgraham]

20+ years, never went back once other than CCR training.

 

[BoltSnap]

20+ years, never went back once other than CCR training.

Never went back to what?

 

[VikingDives]

Never went back to what?

To learn how to use an octo, of course.

 

[happy-diver]

 

[J-Vo]

Another alternative...

Use a bottom stage -- think you call them ponies. Breathe off the backmounted cylinder until you get to the bottom, then switch to the bottom stage and "empty" that (50 bar / 750 psi), then return to breathing the backmounted cylinder.

Always use the backmounted cylinder for the ascent and climbing back on the boat -- 'cos you can remove the bottom stage if its too heavy.

Interesting. When I do open water stage dives, I start on the stage and breath it empty reserving min gas in my primaries.