Doubles vs Sidemount

[LiteHedded]

You are right. There is no need to use that term in an atmosphere open-discussion. I guess I am somewhat defensive as I have heard that term on the "street" (so to speak), have perceived some "attitude" on this board, and those articles are not that old. I will refrain from using it.



Those articles are dated 2011, or so it says - that would make them about 2 years old.

And BTW - SIDEMOUNT ROCKS!!

That's the date they were post edge to whatever awful website you pulled them from. Not when they were written

 

[rjack321]

That's the date they were post edge to whatever awful website you pulled them from. Not when they were written

They were written in about 1996-8 IIRC?

---------- Post added March 13th, 2013 at 01:02 PM ----------

Those articles are dated 2011, or so it says - that would make them about 2 years old.

If you'd actually been deco or cave diving longer than that you'd know they were written in the 1990s...

 

[TSandM]

I've gotten a chance to play with sidemount three times now. The first time, I didn't like it at all, but the rig wasn't well adjusted. The second time . . . well, I agree with vicp on this one, it was heaven! I spent 45 minutes in and out of the cavern at JB playing, and I mean playing. Upside down, right-side-up, on my side, on my back, perfectly stable and comfortable in all those positions. I was in love, and ready to go home and switch over.

BUT . . . it turns out that there were some real issues to face. To begin with, it's relatively difficult to put together or find a sidemount setup that works well in cold water with steel tanks. It can be done, but most rigs are optimized for cave diving, which isn't done in 45 degree salt water. Second, there is no consensus at all on what the best setup IS, or how to put it together, and there are lots of options and variations, and I'm not one of those people who gets off on gear-futzing. And third, I realized on my next trip to MX that having to take multiple single bottles down three flights of uneven stairs was no better than throwing two of them on my back, where I could at least use the handrails. (I'm too short to carry Al80s hanging down from the valve, so I have to hold them in two hands, which means I have to negotiate the stairs without the handrails.) I did come up with a solution for this on the last trip, which I haven't tried, but it involves putting the tanks in a backplate with cambands and carrying them down that way, and I still get to make three trips up and down the stairs.

Where Rob Neto dives, you can put the tanks on a handtruck and take them to the water's edge. Not so much in Mexico.

I've also done a little bit of diving with sidemount buddies. Except for Curt Bowen and Ben Martinez, they've all been much slower to be ready to dive than those of us who just throw on a set of doubles. It's clear that, if you have your gear set up just right and you dive it often, you can get pretty fast (and I was diving on a boat with Curt, who quietly and efficiently geared himself up just as fast as anybody else there, including the single tank people.) But when you're new at it, it's very time consuming.

So right now, I'm still diving BM, on the theory that almost all dives can be done that way, and I know the system, and have all the kinks worked out of it already.

 

[Ulfhedinn]

I know you guys don't think much of the z-system, but it eliminates many of the "conventional" SM issues while bing compatible with a BM rig. I for one love it. Second stages already connected to my harness, routed in "standard" BM style. Just attach the bottles and go.

I like the Z-system and dive it. I also like BM and dive it too.

I have dove BM single and double and SM single and double. For me what side mount offers is optimal for pen dives. I have never dove a cave but I assume and I could be wrong but its a lot like a wreck in that there are some tight spots. SM excels in this area.

The only down side I was worried about at first tell I upgraded my wing was the ability to use steel or multiple cylinders. Not that I have the Z–Trim+ PRO I am happy as a clam.


Now I don't have the a bazillion dives under my belt in all kinds of environments but it seems to be that the BM vs SM issue comes down to what tool works best for "YOU" in the diving you are doing.

 

[Teller]

Can you access that gas if the oring on the first stage fails?

Yes, there's a number of options to access that gas.

Can you explain a few of these options besides swaping regs and breathing on the valve directly?

 

[rjack321]

I realized on my next trip to MX that having to take multiple single bottles down three flights of uneven stairs was no better than throwing two of them on my back, where I could at least use the handrails. (I'm too short to carry Al80s hanging down from the valve, so I have to hold them in two hands, which means I have to negotiate the stairs without the handrails.) I did come up with a solution for this on the last trip, which I haven't tried, but it involves putting the tanks in a backplate with cambands and carrying them down that way, and I still get to make three trips up and down the stairs.

Carrying them down is really terrible - and as you said takes both hands. I carried mine 2 at a time by the valves and by the end of a week I realized I would have been much better off with the weight on my back. Getting doubles out of the car and onto a bench is hard on the back. But once they are strapped on its not bad. Backs + hips are meant for carrying a load.

Taking 2 singles out of the car is easy breezy. Actually getting them to the water is not as easy as the internet would suggest. I'm 5'8" and can just barely carry an al80 by the valve. If the ground is rough like at No Hoch I have to shrug my shoulders which is brutal after awhile.

Using a plate with cam bands sounds ok, except that you have to assemble the rigs down at the cenote. And make twice as many trips although at least one hand is free for carrying the band etc. And bring down a plate on the plane.

Cam bands and clips for SM adds up to alot of extra weight in your checked bag BTW. I weighted mine compared to just the Ali plate + wing and everything together was around 6lbs heavier.

 

[Adobo]

Taking 2 singles out of the car is easy breezy. Actually getting them to the water is not as easy as the internet would suggest. I'm 5'8" and can just barely carry an al80 by the valve. If the ground is rough like at No Hoch I have to shrug my shoulders which is brutal after awhile.

Similarly, carrying a set of doubles (even big ones) from the parking lot down the dock to the boat is far easier when they are strapped to your back than carrying 2 aluminum 80s by the tank valves (one stage, one deco bottle).

For better or worse, I am really only good for carrying a pair of aluminum 80s for 100 or 150ft before I need a break. I imagine it only gets worse if one is diving bigger/steel tanks.

 

[rjack321]

Similarly, carrying a set of doubles (even big ones) from the parking lot down the dock to the boat is far easier when they are strapped to your back than carrying 2 aluminum 80s by the tank valves (one stage, one deco bottle).

Ditto that.
At least for me, the whole "sidemount is easier on your back" is bunk. Individual tanks are easier to get assembled and pick up in-out of the car without the "lift + twist" motions which can be so hard on your back. But actually carrying them from car to wherever is generally harder on back, arms, and shoulders/neck than walking doubles on a plate.

 

[JamesK]

Ummmm you can always do what I do at times. Clip the tanks on and walk. Works great. The lower center of gravity compared to back mount makes walking hills and rocks easier IMO.

 

[DevonDiver]

Lets pretend, for fun, that the ability to modulate flow precisely with 'feathering' the valve is difficult, and this is perhaps amplified while under stress. For the sake of argument....

Why pretend that, when it's not?

I teach feathering, amongst numerous skills on sidemount courses. Of all the new skills to be mastered, students tend to find feathering amongst the easiest.

By feathering the valve ~12 times per min (and that's on the low end, I would bet that a stressed diver's breathing demands are a wee bit higher), how many 1.5-2 seconds valve openings are you going to get?

You wouldn't fully open the valve when feather breathing. It's just a crack open from fully closed - that'd change your expected flow rate somewhat.

By biggest beef with SM is that a real failure effectively makes you lose half your gas. You might be able to get at some of it, but not easily. In BM, you get it all. Everything you have left is yours to use, no games no gimmicks. You can 'look' at your valves all day long, but broke is broke.

I wouldn't argue that isolated manifold backmount is easier in respect of problem management of regulator ​failures - it's just a case of learning some pre-set shut-down sequences for predictable failures. However, it is wrong to assume/promote that sidemount has no effective response for similar failures.

Feather breathing is a very easy skill. It doesn't 'blast you' as some would have you believe. If that's what those people experienced, then I'd suggest some more practice and/or training, because they're obviously having difficulties with what is an essentially straight-forward and intuitive skill. I teach feather breathing to tec sidemount students and I get overwhelmingly positive feedback on the ease of use. Given that some of those students are relatively inexperienced AOW-level divers, I'm quite astounded that some more higher trained and experienced divers find difficulties with it.

Beyond feather breathing... when dealing with cylinder valve issues or catastrophic failures at the reg-cylinder interface... there is always the option to swap regulators. Given that technical divers are typically carrying at least 4 separate regulators, this promotes a lot of options. Aside from the need to service the swapped regs, I don't see what difficulties people would imagine are presented with this skill. I mean... fitting and removing a regulator from a cylinder is about as basic as a skill can get?

If its a big failure, feathering the valve to access the gas but blowing a ton of bubbles in your face in the process might not be worth it. e.g. if it unleashes a torrent of percolation whch then forces you into touch contact with the line to exit.

It's called feathering, not cranking, for a reason. Ask your significant female other about the need for a 'light touch'.

harden up.

There's no prizes given for doing things the hardest way.