tinkering with the idea of sidemount for rec diving (cold and warm water)

[Bigeclipse]

I am a tinkerer and enjoy trying new things. I currently hold certifications from both PADI and TDI and I have completed TDIs "Intro to Tech" Course and have roughly 200 dives. I am not sure I will go into full technical diving but have dove back mount doubles about a dozen times now, just to try something different and give and prepare for tech courses should I go that route. Do I need to dive doubles, nope, but it was fun doing a 90min dive starting at depths in the 70ft range and then finishing the dive in the 20ft range so doubles were needed on that dive, I do not have a super low sac rate yet but I am working on improving it. I've been contemplating breaking my doubles apart to allow me to have 4 single 100s for single tank cold water diving to depths 100-130ft but I still like the idea of having a set of doubles if I get into another situation where we wanted to do a super long shallow dive which got me to thinking about giving side mount a shot to allow me to still have "doubles" should I desire diving 2 tanks in a dive or go back to tech diving. As an FYI I use a pony(40) on the deeper dives, so do not need the doubles in those scenarios. thoughts?

 

[jgttrey]

IMHO, learning to sidemount is a great thing. especially if you're flirting with tech. Whether you decide you prefer it to your twinset or not, it is worth learning. As you note, it lets you break up your cylinders without losing the ability to do longer dives.

It's also handy when you travel to destinations where manifolded doubles might not be available, yet you want to take two cylinders on dives. Personally, I also greatly prefer sidemount when diving off boats because I can just hand up cylinders, etc., rather than schlep up the ladder or around the boat in twins. I can if needed, but sidemount sure is comfy. Plus, even on recreational dives, it's never a bad thing to have a fully independent gas supply and many recreational operators that would balk at a twinset or rebreather have no problem if you want to sidemount a couple of cylinders.

There are times when a twinset is preferable, for sure, but sidemount is a valuable skillset for lots of reasons.

 

[tbone1004]

I've been diving sidemount since 2009, so before it was really a "fad" and back when there were only 3-4 commercial options.
Back then, I went sidemount for 2 reasons. I have bad knees from sports injuries so wanted to be ahead of the curve if I needed to go sidemount for health reasons, and I was going into cave training and feel that is a better configuration for cave diving.

My knees are still holding up well and I am still diving doubles quite a bit of the time. Heck, I just got done doing 2 weeks of doubles diving while teaching. Doubles are MUCH easier to deal with. Configuration is standard, you can walk around pretty easily provided your legs and back are good. I much prefer diving doubles to sidemount in general.

If you're boat diving, are considerate, and the crew can accommodate it, then it's not a problem. If you're doing a lot of shore diving, it may be a lot less convenient.

If I were you, instead of investing in sidemount, I'd plug your doubles and run as independent doubles. Gains you the convenience of being able to use as singles if you want/need to, but means no investment of time and money in changing gear configuration.

I would stop using a pony and use a real redundant system though

 

[txgoose]

I would stop using a pony and use a real redundant system though

I am curious, do you mean full sized redundant or some other drawback not size related?

 

[tbone1004]

I am curious, do you mean full sized redundant or some other drawback not size related?

If you are concerned about having a redundant source of gas for a dive, then just commit and go to either twin tank sidemount or doubles. Pony bottles to me are almost always undersized, though at least @Bigeclipse is using the ideal pony bottle size, but the PITA factor of dealing with them doesn't outweigh the benefits of just going to doubles.

He has HP100's, and presumably is doing 2 dives/day. So for logistics, he is carrying 140cf per dive, and has 3 tanks. The AL40 weighs ~25lbs with rigging, valve, regulator, etc. A Faber FX100 is ~50lbs similarly. These are rounded up by a couple pounds for easy math. So he's carrying a total of 120lbs ish across three tanks, but only has 140cf of gas. This is not including any lead that he is wearing on top of the normal single tank rig.
Alternatively, he can increase his "on land" weight by 25lbs *offset by a potential reduction of ~6-8lbs for the the bands and manifold of the doubles and the negative buoyancy of the second tank. This gives him the advantage of 200cf of gas on each dive which may allow a dive time extension, but also gives an extra safety buffer. It also has the benefit of not having to deal with the pony at the surface or in the water, and not having to swap tanks around between dives. All in all, a much more convenient dive system and a no-brainer to deal with the little bit of extra weight IMO.
Sidemount has the same benefits vs. singles+pony, but you have the hassle of actually diving sidemount for surface work if you have any sort of walk that can't be done with a cart, or the hassle of the cart itself, handing bottles around on a boat, etc

 

[txgoose]

Thank you, @tbone1004 for the write up. I was asking because I have been readily toying with a pony bottle purchase. and I will admit that I had similar thoughts in the dollars per cubic foot sense. For about $10 I could move from an AL40 to an AL80. Ties in well with your similar thoughts on weight. For both angles, with a tad bit more outlay (work or dollars), you get a lot more CF air.

EDIT: Will I get banished to a dark corner if I were to do a back mount AL80 and a slung AL80?

 

[tbone1004]

@txgoose I wouldn't use an 80 as a pony. If you're going to that, you're nervous about gas volume in case of an emergency and/or redundancy. If you need anything bigger than a 40, use doubles or twin-tank sidemount. You've got 4 big bottles already, you don't need a pony bottle where you're carrying 3 tanks around instead of two and have no advantages by using a large pony to one of the proper redundant systems.

There's no dark corner for backmount 80's with a pony 80, but if you're kicking anywhere you get a serious SAC penalty from all the extra drag

 

[Bigeclipse]

I've been diving sidemount since 2009, so before it was really a "fad" and back when there were only 3-4 commercial options.
Back then, I went sidemount for 2 reasons. I have bad knees from sports injuries so wanted to be ahead of the curve if I needed to go sidemount for health reasons, and I was going into cave training and feel that is a better configuration for cave diving.

My knees are still holding up well and I am still diving doubles quite a bit of the time. Heck, I just got done doing 2 weeks of doubles diving while teaching. Doubles are MUCH easier to deal with. Configuration is standard, you can walk around pretty easily provided your legs and back are good. I much prefer diving doubles to sidemount in general.

If you're boat diving, are considerate, and the crew can accommodate it, then it's not a problem. If you're doing a lot of shore diving, it may be a lot less convenient.

If I were you, instead of investing in sidemount, I'd plug your doubles and run as independent doubles. Gains you the convenience of being able to use as singles if you want/need to, but means no investment of time and money in changing gear configuration.

I would stop using a pony and use a real redundant system though

thanks for all the info. I have all the necessities to make my regs and bottles into side mount config with the exception of the side mount rig itself which I was considering the Hollis SMS75. To me, slinging the 40 as a pony is easy and I like the fact I can carry into the water by hand and then strap it on. I do a lot of shore diving and walking back mount doubles any further than 50ft for me sucks haha. In side mount, I could carry one bottle to the shore at a time which sounds nice. I do 90% of my diving in fresh water lakes and quarries. No boats on the lake I dive allow back mounted doubles but one boat allows side mount, although the dives id be doing are only to 100ft in that lake and a single 100hp nitrox and the pony as backup has always been more than enough in that scenario. I guess I was just looking for an excuse to try something new haha. I do not have the time to go full blown tech classes right now or else id be focusing all my efforts in that direction I think. Anyways, thanks for all the information!

 

[tbone1004]

@Bigeclipse weird they don't allow doubles unless they don't have any benches with racks, but their boat their rules. If they don't allow doubles or sidemount, then they may not want you with a third good sized bottle on there and would be a bit annoying.
If you don't like trekking around with doubles *can't blame you*, then sidemount may be a decent option to look at. SMS75 is good and if you're patient they tend to show up used decently often

 

[Diving Dubai]

Will I get banished to a dark corner if I were to do a back mount AL80 and a slung AL80?

Some times I will sling an Al 80 in backmount - I don't find it an issue. They reasons why I might would be;

Can't get a Al 40. I travel with adjustable stage slinge (cam belt) If i can't have a 40 I'll take and 80.
If I'm away for a weekends diving, then the '80 makes more sense. Having more volume, and because I generally keep air in it, I can switch to it if I want to go below MoD
Some sites I dive, from experience - if mother nature bites, a 40 doesn't give you the time options of an 80.
Generally though I'll sling my 40