Sidemount or Backmount?

[victorzamora]

That's correct. Like in independent doubles (same as sidemount), there is no single failure that would cause total loss of gas in isolated doubles.

 

[Vegan Shark]

That's reassuring Is a drysuit considered necessary for the redundant buoyancy when diving heavy steel doubles with no ditchable weight? Or will a double wing for redundancy work, and if it's the hose/first stage/inflator/etc. instead of the wing that has a failure, I can just orally inflate?

 

[WhiteSands]

I heard from an avid GUE Cave 2 diver that BM affords longer range, and there are a number of places SM divers cannot reach.

Granted his viewpoint might be skewed but how true and how important is that point?

 

[DevonDiver]

I heard from an avid GUE Cave 2 diver that BM affords longer range,....

Range is dictated by cylinder volume and gas management. I can't figure how BM vs SM comes into it.

i.e. How would a BM diver with 2xAL80s have longer range than a SM diver with 2xAL100s?

....and there are a number of places SM divers cannot reach.

A SM diver can fully or partially detach one or both cylinders - enabling them to fit through any space that they could move through based on their body size. I fail to comprehend how a BM could ever achieve that.

Examples that might indicate a 'fecal quality' to the avid facts presented by the aforementioned cave diver:







---------- Post added December 14th, 2013 at 01:12 PM ----------

That's reassuring Is a drysuit considered necessary for the redundant buoyancy when diving heavy steel doubles with no ditchable weight? Or will a double wing for redundancy work, and if it's the hose/first stage/inflator/etc. instead of the wing that has a failure, I can just orally inflate?

Rules/recommendations vary from agency to agency. Most accept drysuit as a means of redundant buoyancy. Some agencies don't accept redundant bladder wings (i.e. GUE).

Oral inflation is taught on Open Water and remains a valid technique at all diving levels. That said, orally inflating a larger capacity technical wing at extreme depth, in a timely manner, presents issues.

 

[Ragnar]

I heard from an avid GUE Cave 2 diver that BM affords longer range, and there are a number of places SM divers cannot reach.

Granted his viewpoint might be skewed but how true and how important is that point?

I am not cave certified, but.....I believe using GUE procedures the answer to your question would lie in the calculation of minimum gas and turn pressure based on one tank instead of two that are connected. Since in sidemount they are not manifolded (I'm ignoring UTD here) then the minimum pressure calculated would be higher and need to be maintained in each individual tank causing the turn to happen quicker.

Kinda confusing I know, but since doubles are manifolded and manifold failures are so extremely uncommon it's accepted in planning that you will still have all gas available given a single reg failure. Anything beyond that, such as a manifold failure, you would then be dipping into your 1/3 reserve for the overhead environment and still be ok based on the plan of that particular dive. Beyond that you're in a gas sharing situation.

To be very clear, I'm not bashing sidemount, for sure there is a place for it, I'm just questioning the current trend toward it in all cases when there is really no need and manifolded doubles offer a more simple and sometimes safer option. The more complicated the diving becomes, the more planning needs to be done, and with sidemount it's a little more complicated, I hope the training organizations are teaching that.

 

[Pullmyfinger]

^
That first video is pretty cool.
In defense of sidemount vs. doubles; in regards to "need".

Sometimes divers dive double tanks when it isn't necessarily needed.



They might be diving their doubles rigs just because they want to, of just because it cool to dive your doubles sometimes.
I get side mount. It's kind of cool....nothing at all wrong with that. In some ways, it's kind of good for diving.

I'm not about to switch! I just bought a rebreather....... and I already have plenty of doubles gear, and the training that's been based on manifold doubles.

Side mount is kind of cool, IMO.
I won't be dropping money on it any time soon........slippery slope.

I will say that avoiding valve drills is an odd reason to choose side mount.....valve drills, aren't really that difficult.

 

[Doppler]

To read and consider a slightly different viewpoint I suggest looking up an article I wrote for X-Ray magazine earlier this year.

kicks off section five of issue#56

X-Ray Mag #56 | X-Ray Magazine

---------- Post added December 14th, 2013 at 06:37 AM ----------

I will say that avoiding valve drills is an odd reason to choose side mount.....valve drills, aren't really that difficult.

I have two or three students who switched because of shoulder problems that made shutdown drills very taxing.

 

[DevonDiver]

I am not cave certified, but.....I believe using GUE procedures the answer to your question would lie in the calculation of minimum gas and turn pressure based on one tank instead of two that are connected.

GUE haven't released procedures for sidemount yet. When they do, I doubt they'll base calculations off a single tank. From what I've read (Jabblonski) GUE won't be advocating mixed team diving, so no UTD manifolds. Sidemount will be "a tool" for dedicated sidemount passage dives, in all-sidemount teams.

Since in sidemount they are not manifolded (I'm ignoring UTD here) then the minimum pressure calculated would be higher and need to be maintained in each individual tank causing the turn to happen quicker.

Why would the minimum gas need to be higher?

The tanks are balanced in use anyway. That's something all sidemount divers learn.

To be very clear, I'm not bashing sidemount, for sure there is a place for it, I'm just questioning the current trend toward it in all cases when there is really no need...

Divers tend to adopt a single approach and stick with it; thus maximizing their familiarity and configuration-specific experience. This is the same for back-mount or sidemount.

Those divers who switch to sidemount because they have, or will develop, a 'need' for it, might feel inclined to dive sidemount near-exclusively from that point onwards.

...and manifolded doubles offer a more simple and sometimes safer option.

Personally, I think there are both pros and cons to the consideration of simplicity and safety with either configuration. Let's not try to portray sidemount as some sort of complex 'voodoo' diving when it isn't. It's pretty straightforward... even novice OW divers are learning it.

The more complicated the diving becomes, the more planning needs to be done, and with sidemount it's a little more complicated, I hope the training organizations are teaching that.

The gas management and dive planning considerations for sidemount or backmount are virtually identical. It's not complicated.

Have you seen Steve Bogeart's presentation to the GUE 2010 conference?

http://www.gosidemount.com/download/GUE_WhySideMount.pdf

 

[TSandM]

Double bladder wings are one solution to the problem of redundant buoyancy when diving big double steels. If you hook both up to LP inflator hoses, you have a problem in deciding which one is malfunctioning if one starts to auto-fill. If you don't, you have the delay in hooking up (or orally inflating) if you need the redundant wing. And you have the annoyance of having two corrugated hoses hanging down. It beats diving heavy steels (especially in a THICK wetsuit) with no redundant buoyancy. But given that deep dives and long dives are thermally challenging anyway, the dry suit makes an excellent solution to the problem of avoiding being an obligate lawn dart.

 

[PfcAJ]

BM diving does afford better options in regards to stage bottles. I've yet to see a diver with multiple stage bottles look like anything other than a starwars tie fighter moving through the water. I'm sure it can be done, but from what I've seen, not cleanly.

My view is that if you NEED sidemount (small cave), then use it. But learn on BM, as its simpler and affords more gas in event of the most common failures. I think a lot of divers out there are lucky that serious failures don't happen more often, these days. It wouldn't be pretty.