Question Rec cold water diver: Single, Double or Sidemount? (focus on safety)

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I have some big singles with H-valves, but with a single tank adapter on a backplate I discovered I actually have a harder time reaching the valves on those than on a set of doubles.
 
I have some big singles with H-valves, but with a single tank adapter on a backplate I discovered I actually have a harder time reaching the valves on those than on a set of doubles.
I am really liking my manifolded Faber LP50's for solo rec diving. Simple, relatively small, fully redundant kit that wears well whether portaging or diving. Not terribly heavy (~40 lbs) out of the water. Wetsuit friendly. (Medium thickness wetsuit.) Max buoyancy when full requires only a relatively small BC (small wings). Your torso will remain uncluttered!!

Downsides: Some shops will charge you double for a fill, I think. You'll probably need a second set (since it's unlikely that you will be able to squeeze two moderate-depth rec dives out of a single set). And you just might NOT be able to get a generous fill in these LP cylinders.

I love a medium capacity single with two complete regs on a Y-valve--long my preferred kit for these local, walkout, moderate-depth rec dives. However, my double LP50's seem now to be becoming my fav.

rx7diver
 
I used to use a hp120 to transfil into the 50's for dive 2. Now I just got another set instead.
 
Safety is priority number 1. Only diving with a buddy (or in a small group), never single.
Safety should always be #1. You may at some point change your mind about solo-diving, and I'm not trying to convince you to do that.

Having another diver watch your back is an amazing thing. However, the #1 goal is always safety (which allows you to dive again and again). However, having a buddy for redundancy is only one-of-many things you can do to get there. Pursue the goal (safety) and not the means (buddy, etc).

A self-reliant course (sometimes called "solo diving course") is a fantastic way of pursuing safety. Your buddy may be unavailable for any number of reasons, and being able to self-rescue is huge. Not to mention, it makes you a better buddy. Same goes for the rescue-diver course; on the surface it's about rescuing another diver, but many people advocate the course for making your own dives safer.

I wonder which are the opinions of experienced divers which setup would be "best" or which have negative sides which could be eliminated with an "upgrade":
Complete redundancy is the ONLY way to be sure you have ... complete redundancy (tautology!). In other words, pick ANY point in your setup, and lets say that fails for any reason. Do you have enough accessible air to safely get you to the surface?

Therefore, the safest route is to always have a completely separate, redundant air-source. That includes tank, valve, 1st-stage, and 2nd-stage.

Lets say, you have a scenario where a 2nd stage comes unscrewed, hose unscrewed, 1st stage fails, tank o-ring fails, etc. Some of these may be unlikely scenarios, but if you were running manifolded doubles, and 1 first stage, you'd only be able to address some of those scenarios.

Sidemount.
I love side-mount. If you're interested and motivated, go for it! It does have a steeper learning-curve, so I don't recommend it for every diver, but I'm getting hints you might enjoy it.

A single tank is as safe as a double tank (my assumption)
You can do "independent doubles" which is 2 full size tanks, but also 2 valves, and 2 complete regulators.

The other thing you didn't mention, for some reason is doing a normal backmount setup, but slinging a pony-bottle. A 19cu pony bottle is what I consider to be the ideal size. (others may disagree, but that's my preferred). It's about at the right point for recreational diving, where you'll have plenty of air to surface, with safety stop, and not feel rushed. It's also fairly light-weight and unobtrusive.

13cu and 6cu are technically smaller, but I've found the 6cu adds as much noticeable bulk as the 19cu. So, why not go for 3x the air?
 
@Wildsparrow

Based on what you’ve written, I think the first thing that will really satisfy you is more advanced training and then assembling a small arrayal of equipment (single tank, twinset and sidemount) to suit the particular dive profile you’re pursuing.

I dig the metaphors with sports cars and espresso.

You’re doing a good job focusing on safety but it sounds like you’ll eventually become hungry to learn how other divers go deeper and longer while possessing an even keener sense of safety than recreational divers.

I think you’ll be well-served to talk face to face with an instructor with credentials. Look for demonstrated expertise over enthusiasm.
 
@ginti Option (1) is not in consideration. Thanks for answering my question in (3). I agree, anything below 12l seems to be not enough - I would also strive to have at least 14l of air with me (though 24l seems to be too much - and then I haven't looked into 300 bar, but focused on 200-232bar). I did not say that SM is superior (in that case I would not think of going BM), I said the "technical" feeling could be something I would really enjoy :)
If this is the case, all the configurations you mentioned have the same level of safety against free-flow.

The advantage of two tanks (side- or back-mounted) is that you still have one tank if you lose the other one; to lose the other one, you need a major failure on the bottleneck or something similar. Extremely rare, especially in rec diving. The other advantage of double tanks is that you can bring significantly more gas (imagine a single 24l - not exactly a comfortable configuration).

If you have a fundies instructor close to you, go for it, you will get training on all these details. However, keep in mind that side-mount and pony are not allowed with fundies.

P.S. @formernuke , guess what? To me, a pony bottle is a marketing scheme, while a Y-valve is a perfectly functioning tool. I believe it is a point of culture because, if you think about it, both serve their purpose and have advantages and disadvantages.
 
P.S. @formernuke , guess what? To me, a pony bottle is a marketing scheme, while a Y-valve is a perfectly functioning tool. I believe it is a point of culture because, if you think about it, both serve their purpose and have advantages and disadvantages.
That was my impression, too. From what I have seen and heard, in the US ponies are the more popular solution, while in Europe the H-valve/Y-valve is the more popular solution. I'm sure we could have an entire other thread in which the advantages and disadvantages of each solution are debated.

However, that does bring up a good question. @Wildsparrow , what equipment configuration are other recreational divers in your region using? Find a local mentor.
 
... For recreational diving stuff my favorite setup are my lp50's doubled with manifold. ... I think these would be 6 or 7 liter tanks in metric. They trim better than a large tank and are more comfortable both in and out of the water than a single large tank. I especially like them since I cave fill them for a good amount of air.

... For me all I dive right now is backmount doubles. I use my small lp50's for rec ...

+1

rx7diver
 
SM not ideal for boats, depends on local customs if it is allowed or not.
I take the approach of not caring what others think. SM is fine for boats, it's just that one will need a lot more practice and perhaps some gear adjustments to get your donning speed similar to that of BM.
I have never seen a pony bottle in Europe, but I am not that experienced - maybe there are many. Anyway, it is an alternative, and the OP should consider it if it is his style.
Completely disregard what is common or popular, unless there is a legitimate safety reason for something being common or popular.
 
I take the approach of not caring what others think. SM is fine for boats, it's just that one will need a lot more practice and perhaps some gear adjustments to get your donning speed similar to that of BM.

Completely disregard what is common or popular, unless there is a legitimate safety reason for something being common or popular.

Are you still going to tell the captain to eff off and dive SM off his boat if he forbids it? We’ll see how well your “don’t care what others think” attitude works in that situation.
 
https://www.shearwater.com/products/teric/

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