ok. Nothing wrong with having a sidemount rig in your repitoire.
But understand our concern... anyone
ready to buy a sidemount rig and dive sidemount wouldn't generally be asking about its appropriateness for use on deco dives.
Rick
It's not exactly news but sidemount as a OW configuration is catching on.
In that regard you have to recognize that there is a difference between diving sidemount and sidemount diving in a cave environment and that makes your statement more or less irrellevant.
I share the opinion expressed above that if I were just getting into cave diving, and in particular if I had not come to cave diving with a decade of back mounted technical diving experience, I'd start in sidemount. You can go anywhere in sidemount that you can go in back mount but the reverse is not true, so why choose to start with a much more limited configuration if you'd have to learn either one from scratch anyway?
In that regard, if given the option, I'd start in sidemount in OW, or at least start with a nomad that could be used for single tank backmounted Ow dives and then readily convert to sidemount use with doubles.
I do agree that just having a sidemount configuration does not in any way mean you are ready to tackle caves that require sidemount, but when you get to that point, the transition will be a lot easier if you are just refining/adidng additional sidemount skills as opposed to transitioning from backmount.
In that regard, I get the impression that the OP is asking if it makes sense to start in sidemount for deep offshore diving. It does to a point.
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The configuration itself is very comfortable and the gas management requirements are minimal - 2 reg swaps per dive are all that is required, although that is a hot button issue as many SM divers prefer 300-600 psi reg switches.
A potential downside for offshore boat diving is that the tanks are not as secure as in backmount. I am not sure I'd want to hop on and come up a pitching boat ladder in 6-8 ft seas as the less secure and more mobile tanks could cause smoe weight shifting and/or catch on the ladder at a very bad time. An option would be to remove the tanks and have them hauled aboard on a gear line, but that would require some coordination with a willing crew. Depending on the boat, gearing up could be difficult in roiygh weather as well compared to backmount.
DR recently came out with a set of ring bungees that carry the load to the D-ring with metal to metal connections and that might be very useful for boat diving in rough conditions.
In the other extreme, diving out of an RIB or similar small craft with low freeboard would be much easier in sidemount.
Stages can be top or bottom mounted, and you can do both at the same time allowing 4 stages in addition to your primary tanks and all of them are fairly clean and streamlined compared to how they would look in backmount.
A regular stage strap arrangement works but is not quite as clean as some of the other options. Search youtube for dive rite videos and you will find one that addresses a different approach developed by Edd Sorenson and demonstrated by Lamar Hires using a bungeed bolt snap on the neck and another on a cam band or hose clamp 15" down the tank.
The same applies to deco bottles. For a steel 45 I tend to use a regular stage strap but with the bolt snap move closer to the valve to keep it cleaner, or I'll use a choker on the boltsnap to accomplish the same thing. Generally in sidemount if bottom clipping a stage or deco bottle, you are working under the left or right bottle, so clipping is slightly harder than in backmount, but with properly located tanks and D-rings the difference is minor.
Hose arrangment on a stage can be another difference. In the normal DIR approach everything gets clipped on the left and that still works in sidemount to some degree but for trim purposes you will find yourself clipping and using stages on the right. I was not real hot on changing, but in my opinion, the hose routing is in fact much better if you tailor the hose routing and use a shorter hose to configure the reg for that side.
Generally, I prefer to top mount a stage as it stays out of the way better and I prefer to bottom mount a deco bottle as it gets dropped in the cavern anyway, is easy to see, identify, and it is easy to manually trace the hose when doing the gas switch. But that is a purely personal preference.
