Doubles vs Sidemount

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Devon, you and I both know that no two valves are exactly the same. I've got some in my fleet that are easy to open 'just a hair' and some that are pretty much on or off. Same w/ rental tanks, borrowed tanks, etc.

Relying on that trick to get at your gas is suspect at best. Being on the line or on a scooter complicates things even more as you're quickly running out of hands. In a pool, its probably great. But I don't dive in pools ;)
 
---------- Post added March 13th, 2013 at 08:47 PM ----------

Here is my 2 nickles. BM is because BM is. It is what has always been dove, the system has not only adapted itself to emcopass the configuration. but it has established lmits based on the config also. What limitaitons you ask. Well since you are pulling it out of me. Max air you can carry based on how much dry weight you can haul to the water line. Face it you dont see much of 120 and larger lp doubles pumped to ____ psi. If anyone is diong that I for one am not going to offer any unwanted lecture on the evils of over fililng. many can carry a single 120 or larger to the water line and double up in SM fashion and not strain something. When I was doing classes in cave.... i saw more SM then BM. granted only because there was a SM group there but never the less it is popular and gaining in that respect. Imagine what youcan do with a pair of lp150's at _____ psi and you have 500 cu ft to explore with not counting your stages. And you can still carry them to and from the car.

When time comes and you need to drop weight you drop tank instead of lead

I think that SM is not any where near reaching its aceptance and use potential.
 
Devon, you and I both know that no two valves are exactly the same. I've got some in my fleet that are easy to open 'just a hair' and some that are pretty much on or off. Same w/ rental tanks, borrowed tanks, etc.

I think you're being pedantic. It's an easy skill. If my minimally qualified/experienced students find no difficulties with it... then frankly, an experienced diver has no excuse.

Now...I don't think people are making excuses... I think they're hypothesizing, on the basis that they've never really put any effort into learning that skill. Well, thanks for the hypothesis.. but I'm saying from practical experience, the hypothesis is incorrect.

Again,.. if it were just me that found it easy... then I'd accept that the technique might require certain expertise etc.... but it isn't just me... properly trained sidemount divers adapt to this skill very quickly and intuitively.

Relying on that trick to get at your gas is suspect at best. Being on the line or on a scooter complicates things even more as you're quickly running out of hands. In a pool, its probably great. But I don't dive in pools ;)

You think I just dive in pools? LOL I don't endorse stuff unless I've used it 'in anger'. If a diver couldn't manage the task loading of feather breathing, then they'd have no place in a cave, on a line running a scooter. You train to do this... it's a skill, not a 'trick'. The same as any skill you intend to use... proper training using proper technique... sufficient and realistic practice appropriate for the environment/activity... ingrain it.... remove the task loading.

Air sharing... in a pool.... in a cave....in a cave on a line....in a cave on a line running a scooter... same skill, different levels of application. Appropriate and realistic training is all.
 
You were the one arguing that SM is so awesome since you can't "really" lose all the gas in one tank and that you can feather the valve and do other such imporvisations to access it. Things which backmount doesn't require at all with a simple reg failure. Glad to see you've changed your tune on that.
With all due respect, I have not changed my tune. I still feel safer seeing what is going on with the tank and valve in front of me rather then trying to figure out what the heck is going on behind my back. I don't feel that I (and a probably a lot of other people doing BM doubles) are that good and fast to shut down and isolate the proper valve without losing a lot of gas and possibly shutting down the wrong side and panicking. I know I can shut down the the proper valve that I see in front of me and I have been able to breathe from a free flowing reg by feathering the valve that I can see. There is a very good reason SM is used for solo diving (I know it's not DIR - team and all), the redundancy of having 2 independent gas supplies.

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

Nevertheless, they are on current web sites with those dates. The site is not awful - I believe it is a Dutch Tech diving site that has 27 of George's articles published. The Bible was written hundreds and thousands of years ago and is still published and seems to be used weekly on Sundays if not daily.

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.
Hey TS&M - isn't that what it is all about? It is for me. While I love the technical aspects of diving (I am a scientist/engineer and a pilot), I dive for the sheer pleasure of it. SM gives me the freedom to fly through the really neat caves and pretty reefs out there in a way that is so much freer than any BM setup. If you feel that you may need to go that way eventually (for whatever reason), the sooner you do it the more you will enjoy it.

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.

If you get together with either Edd Sorenson (Cave Adventurers) or Rob Neto (Chipola Divers), they will get you squared away in a day or two for most of what you would need to put together a sidemount setup that would work for you. I am sure that would include any modifications you might need for your cold water diving. How much different is your BM cave setup from your cold water setup? Probably some differences in exposure protection and the weighting associated with it. That would be the same for SM. I personally like to tinker, so I got the stock SMS100 and applied and changed out mods while picking Edd's and Rob's brains - but that is me. Others have had Edd or Rob set them up and have been very happy with the outcome. Didn't you have some gear-futzing in BM when you started? I did, and a lot more than with SM.

Also, there is a growing community of SM divers, especially here in Florida. Over the last several years there have been more and more SM divers at the springs. Now, on any given day in "cave country" (Peacock especially) you will find more SM than BM divers (and quite a few rebreathers). If that has not happened yet in the PNW, I am sure it will change. We also dive mixed teams all the time - BM, SM, and rebreather. Not a real big deal and easily doable. There is no reason to remain solely BM, the diving community will accept you whatever your preferred configuration as long as you as your diving skills are commensurate with your team members.

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.

The logistics of getting in and out of the water with SM is fairly varied and easily adaptable to the person, situation and location. Agreed that with BM, your rig is set up (wherever you do it), strap it on, walk to the water, put your fins on and jump in. You can actually do the same with SM and some people do exactly that. You also have the option of taking you tanks down to the water, one or two at a time, with a hand truck or just carry, then put on your rig, walk to the water, then attach your tanks (in or out of the water) and you are set to go. While this may seem more complicated, it is actually very versatile. At Peacock (and most of the other springs), I will put together my tanks with regulators, and take them down to the water, one or two at a time (carrying or hand truck) and put them in the water (attached to a tie off line if necessary). I then leisurely go back to my car or staging area, put on my rig, make sure I have everything (reels, computers, lights, cutting devices, etc.) then leisurely walk down to the water, jump in and attach the tanks and I am ready to go. If I want to, I can attach everything (including tanks) at the staging area and head for the water and jump in, pretty much the same as BM. Getting out, I have the options of first removing the tanks and clipping them off (if necessary) or simply leave them attached and get out pretty much the same as in BM. You can also remove one tank, and leave the other attached as you exit, half the load of BM. Pretty cool, I think. Lots of options, easier on the body.

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.

If you put your mind to it, these logistics are easily worked out. True, sometimes it may seem easier to simply strap on the BM rig and to navigate whatever obstacle you encounter. I have found that if I think about it, and get some good advice, I can usually figure out a way to not have to muscle all that weight on my back to wherever it needs to go. Each situation may require a unique solution. At worst, I can attach both tanks (we use neck leashes) and transport them as a BM rig. Another option is to divide the weight, although it may take an extra trip, to transport all items to where they need to go. Don't forget, if you have stages and deco bottles, you may need to take extra trips anyway.

BTW, Lamar Hires (Dive Rite) has a SM cam band set up for the particular trim he needs that he travels with. He can then use whatever tanks are available and his trim configuration basically remains constant. Cam bands also come in smaller (1 1/2") and lighter versions. For travel, SM lends itself to be compact, light and fairly versatile. Lots of info out there on how to do that.

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

I am not the person you asked this, but DIN valves and regs do not typically blow connection o-rings (they are trapped vs. yoke) and feathering (turning on and off) a valve that is easily accessible and visible (as in SM vs. BM) is easily doable and is part of many SM courses.
 
I think you're being pedantic. It's an easy skill. If my minimally qualified/experienced students find no difficulties with it... then frankly, an experienced diver has no excuse.
Just out of curiosity are you teaching this skill with an actual broken regulator? For instance remove the DIN-to-valve oring or the DIN-to-body oring. Or remove the LP seat in the 2nd stage. Now have the diver practice and learn this skill. While scootering or following a line blind... I'm not saying it can't be done, but its overrated and you are significantly poo-pooing its real world challenges in an effort to promote sidemount as a gift from God.
 
Vicp, I understand how a DIN connection works. I asked because in the event that it did fail feathering would not work. In BM you still have access to that gas very easily. How in SM would you get that gas without swapping a reg or breathing right off the valve?
 
Vicp, I understand how a DIN connection works. I asked because in the event that it did fail feathering would not work. In BM you still have access to that gas very easily. How in SM would you get that gas without swapping a reg or breathing right off the valve?
Teller, you are correct, if a DIN connection o-ring fails, it may preclude you being able to feather a valve. I honestly don't know how it would fail and how catastrophic that failure would be. All I know is that I have had numerous yoke o-rings fail but I have never had a DIN o-ring fail AFTER I have pressurized the reg and had no leaks. The design of the DIN "captures" the o-ring and it seals. I may be wrong, but I suspect I may have a better chance of getting hit by space junk than the DIN connection o-ring failing if it initially seals. I have had them leak if the reg was attached incorrectly, but never after the system was pressurized with no leaks.

I still feel a lot better if I can see the valve/reg in front of me and knowing that I have another independent gas system to rely on if that one fails.
 
How in SM would you get that gas without swapping a reg or breathing right off the valve?

Why would you need to get to it? Plan all dives assuming that one tank will die at the worst moment. If it does,just close the valve ,breathe the good tank and head for the exit/surface/first deco switch as fast as reasonably possible. If it gets seriously low, breathe from your buddies long hose. KISS!
 
Why would you need to get to it? Plan all dives assuming that one tank will die at the worst moment. If it does,just close the valve ,breathe the good tank and head for the exit/surface/first deco switch as fast as reasonably possible. If it gets seriously low, breathe from your buddies long hose. KISS!

To not drown?

Problems in the cave often result in delays. I've been delayed in a cave on a few occasions, and I'm glad I had access to ALL my gas, and would have access to all of it across the most common failures. I've scootered on the line in legit zero vis multiple times. I know for a fact that it takes 1 hand to run the scooter and 1 hand to feel the line. Where is this 3rd hand that will operate a tank valve? Heck, even in OW, you've got a lot going on between managing the ascent, preping a gas switch, managing an SMB, etc etc.

Devon, you mean to tell me that you, personally, have exited an overhead on the line while feathering a legitimately borked regulator on a real dive? Color me skeptical. Using the technique 'in anger'?

Folks sure do love to fixate on the DIN o-ring. Maybe because its the only one we see every time we go diving? There are a bunch of other ways for regs to go tits up, and they're way more common than any tank neck o-ring or burst disk failure (which are not unheard of). The common ones are the one's I'm worried about, and the isolator takes care of the rest.
 
Back in the 90s double independents were popular but had inherent issues all dealing with gas management. Sidemount, while obviously changing some points, suffers from the same basic drawbacks of that system.
 

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