Twin-set manifold vs Sidemount vs Independent Twins

[BlueTrin]

I would like to extend my training by adding redundancy/extended bottom time.

Options are:

1. Twin-set manifold
2. Twin-set indies
3. Sidemount
4. CCR

I didn’t consider #4 yet because I am new to diving and paying £6k for something that could kill me is not something I need yet, I feel like I can just move to using two cylinders.

I understand that on this board most of people are advocates for manifolds as you can still get 100% of the remaining air for many types of failures.

However I would have preferred to not own my own cylinders as I live in a smallish flat.

My end goal has always been to do visit wrecks and caves and this is what I want to work towards but safely. At the moment I am doing recreational diving to improve my diving.

So if you guys tell me that it is almost a requirement to own your own cylinders when doing cave diving or wreck penetration then I will bite the bullet and buy cylinders as I might as well own them.

But I was wondering if some of you are doing sidemount or independent cylinders with rental cylinders during cave. I suspect the answer is no.

Sorry if this is a silly question but it’s not easy to get these answers, I’ll ask around in my club next time I go there: there are people doing twinsets, but I am interested in hearing many point of views.

 

[tursiops]

Yes, I often rent two cylinders to do SM on caves. I have my own HP100s for this, but I like to have two sets so I don't have to fill between dives. And if flying somewhere to cave dive, renting is required.

 

[divad]

So if you guys tell me that it is almost a requirement to own your own cylinders when doing cave diving or wreck penetration then I will bite the bullet and buy cylinders as I might as well own them.
/QUOTE]

I'm not telling you anything, rather, suggesting you weigh the differences between owning and renting.
Let's see:
Cost.
Convenience
Confidence/peace-of-mind re condition
Chiaroscuro (warm glow emitted by my "twinset" whenever I walk by them).

 

[BlueTrin]

I'm not telling you anything, rather, suggesting you weigh the differences between owning and renting.

Can you elaborate on these differences ?

 

[RyanT]

@BlueTrin, I prefer back mount doubles with a manifold. As you mentioned, easy access to the additional gas is a big plus. Most of my diving is in the ocean from a boat. I have no need for the flatter profile that SM gives me. On a swaying boat, gearing up in a set of tanks that are already solidly together is a plus. Each system will simply have advantages for a particular dive - right tool for the right job. I don't see any advantage to independent BM doubles. IMHO, they seem like the worst compromise of what manifolded BM and SM have to offer.

 

[broncobowsher]

I trained on borrowed twinset.
Switched to sidemount when I needed my own stuff. Nicer to ravel with as well. Go anyplace and rent a pair of tanks. Allowed me to dive either my recreational single backmount or twins (sidemounted) with the same tanks. Keep them filled and whatever I'm doing in the next weekend or two it will work fine. Building and breaking a twinset is a pain I avoid. Sidemount has advantages and disadvantages, I find it is pretty much a wash overall compared to twins. If you pick specific points or situations, yes you can clearly make a case for one being better than the other. There are plenty of twin vs. sidemount discussions.

As for independent doubles. That is getting close to the worst of both worlds. You have to dive them like sidemount. But you have the monkey on your back with hard to access valves like a twinset. Don't have the easy access to the valves to feather them like sidemount. Still have to band the tanks together but without the simplicity of just having all the gas through a single reg for the whole dive. I've never done it, don't plan to.

It is a gear intensive sport. As for taking floorspace, they all grow and take more space. Owning tanks doesn't really take that much more floor space. They stand up in the corner of a closet or can be packed away in other places. Under a bed, behind a couch. I kept gear in a dorm room in college and you would never know it was in there.

 

[Diving Dubai]

Agreed with @RyanT above.

The point of travelling with SM is valid, that's the reason I chose SM

But as we also previously discuss, when/if you start more technical requiring multiple gasses, then the SM some people prefer back mount over SM because the SM cylinders are occupying "valuable real estate" I don't mind, it doesn't' bother me. My friend who is only 5'5 prefers BM for tech diving because of this very reason - but is happy to use her SM rig if she's not on a multi gas profile.

There is of course the personal preference of what feels most comfortable to you.

I also prefer SM because it's generally easier to move the gear around - but I'm grumpy and over 50.

 

[ajduplessis]

Rent whatever you are skilled/trained for and see how things pan out. You will quickly figure out what will work best for you and your situation.

I prefer BM manifold for my situation...

 

[MichaelMc]

Owned cylinders is mostly a local issue. Do you dive boat or shore at home?

I dive shore and two big tanks is more than I want to walk to the water. So I sidemount 2x lp50 and 2x al40 so I can learn heavy and light tanks. Both are hard to rent.

If you plan air travel, getting doubles may be problematic, though likely fine at cave mecas.

Doubles have appeal for: all in one unit easy on, compactness on rough boats, one reg to breath the whole dive. I plan to approach learning them via indie banded doubles to let me keep my tanks sidemount ready, which I think I like more. Then adding a manifold if I like the feel. But that still takes two separate BCs, so it is not saving much space, just tanks. I’d see the indie mostly for this intermediate testing or multi use role or for travel, as you can replicate their separation with a closed manifold.

Mine is all OW, with thoughts of cavern.

 

[tarponchik]

So on a manifold you still have 1 reg, and if it fails, your 2nd tank won't help you. As for the bottom times, I am limited by N2 intake, not by my air supply. My dives, when I dive the way I want to dive, are 1:15 to 1:30 on average already. And when I dive the way I want to dive, why would I bother to carry the 2nd tank if I can simply get out, take a break and dive here again? If you want to have longer bottom times, learn to use less air. If your concern is safety, then OK, double everything, including your buddy (2 buddies are safer than one!).