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

[SlugLife]

When I started learing sidemount, everyone was talking about how it's hard to enter water, you need to kit in water etc etc.
But in reality, two boltsnaps, and properly set up tanks, and you can even giant stride with the tanks attached.

I initially had difficulties diving off my friend's boat. The donning-area was essentially flat (no bench, seat, etc), and any waves would make things worse, as I couldn't really clip on the tanks either sitting down or standing up. Then someone suggests just putting a "long" leash (about 6-inches I think) on the top bolt-snap. Anyway, I can now mostly don both tanks standing with a slight kneel or bent legs, route hoses, etc. Or do the same while sitting on the boat-deck. Then extend legs, giant stride, and finish in the water easily. Or roll into the water if sitting.

I usually clip the bottom and loop the top bungies while in the water, and am good to go.

 

[MrVegas]

@BlueTrin,

When I first returned to the Midwest US after having spent several years extended range diving deep, Great Lakes shipwrecks using manifolded HP120's, I dove my HP120's here as independent doubles for local, solo dives.

They were "perfect" as ID's--except that they hold way more gas than I needed for the solo recreation profiles I began diving then, they are way too negatively buoyant for wetsuit diving, they are way too heavy out of the water for shore diving, and they are too tall to easily schlep.

But, old-school 72's (71.2 cu ft @ 2,250 psig + 10%) just might hit the sweet spot here as ID's (if I need the gas capacity).

rx7diver

I have double LP72s, and I like them a lot, though pretty much no one is going to give you more than 2250psi in a 72, so you're looking at about a max of 130 cubic feet of air in the set. I also have double LP85s, and most places will just fill those to 3000psi, so significantly more air. The 72s are a little easier to get up the basement stairs.

The double LP108s and LP120s look scary heavy to me. I would like a set of LP50s, but those would only be good for one longish dive, really, and there is always the chance that someone is only going to give you 2400psi in the set (even with the + rating).

 

[drakcheslav]

I initially had difficulties diving off my friend's boat. The donning-area was essentially flat (no bench, seat, etc), and any waves would make things worse, as I couldn't really clip on the tanks either sitting down or standing up. Then someone suggests just putting a "long" leash (about 6-inches I think) on the top bolt-snap. Anyway, I can now mostly don both tanks standing with a slight kneel or bent legs, route hoses, etc. Or do the same while sitting on the boat-deck. Then extend legs, giant stride, and finish in the water easily. Or roll into the water if sitting.

I usually clip the bottom and loop the top bungies while in the water, and am good to go.

I usually don all of my gear 100-200m off the entrance near my car, clip the tanks one by one first to the top with a double ender, and then to the waist. And walk like that to the water.

When in water I complete everything.

Same thing on a boat, except I attach my inflator and then roll over.

It works great for me.

 

[formernuke]

would like a set of LP50s, but those would only be good for one longish dive, really, and there is always the chance that someone is only going to give you 2400psi in the set (even with the + rating).

Two sets and your good to go. Even if they do only go to 2400 still about the same as the common 80.

 

[SlugLife]

I usually don all of my gear 100-200m off the entrance near my car, clip the tanks one by one first to the top with a double ender, and then to the waist. And walk like that to the water.

When in water I complete everything.

Same thing on a boat, except I attach my inflator and then roll over.

It works great for me.

Nice! Also reinforced the point of adjusting your (SideMount) gear to suit the kind of diving you do. I've only walked tanks like that a couple times, and if I did, I'd probably adjust both my harness and maybe a small change to my tank-rigging as well.

I'd guess that's probably nicer than walking back-mount doubles. With doubles, you'd need a slight lean to your posture to balance the weight.

For boat-diving, the type of boat makes a HUGE difference. Your setup would work great for a dive-charter layout, with a bench and flat surface to walk towards the water. It could also work for something like a RIB, where you sit on the side, don-gear, and back-roll.

---

My friend's boat was a recreational-boat, with an oval seating area you climb out of to get to a relatively flat rear-deck. You could don most everything inside the boat with a nice "bench", but then climbing the seats with 1 or 2 tanks is super-sketchy made worse by waves. So, donning tanks on the flat-deck means either standing or sitting. Standing with waves rocking the boat, trying to clip 2 tanks, route hoses, etc was also sketchy. That left sitting with feet over the side, tanks on either side, trying to get everything clipped while not really being able to move, etc. edit: Limited space on the deck with another diver donning gear was also a consideration.

The "leashes" I setup make the process was less sketchy, and give me flexibility to clip on whether standing or sitting, and less problems with the waves, since my tanks are mostly just sitting on the deck. They can still tip over, but I'm not supporting the weight and can move around a little while leaving the bottom of the tanks flat against the deck.

 

[Beau Holden]

Quite common in the Great Lakes region for single tank recreational divers to sling a pony for redundancy on cold water dives. Often an AL40. I did it myself for several years. Best option for those who have no desire to do tech training.

I agree, I also did it this way in the beginning in the Great Lakes.

Not sure what the OPs later intentions are as for as BM or SM. I never went SM. If was me me I would start with the BP and wing with a AL80 as main gas and a AL40 as stage. Then later go BM (what ever size you want or a couple or several sizes) and you would have the AL80 and/or the AL40 to sling as deco or stage tanks later. You could also just add another AL80 for you BM doubles. Just my thoughts, and many configurations.

 

[MarkA]

Not sure what the OPs later intentions are as for as BM or SM. I never went SM. If was me me I would start with the BP and wing with a AL80 as main gas and a AL40 as stage. Then later go BM (what ever size you want or a couple or several sizes) and you would have the AL80 and/or the AL40 to sling as deco or stage tanks later. You could also just add another AL80 for you BM doubles. Just my thoughts, and many configurations.

As the OP is from Europe (Germany) where the default cylinder would be a steel 12l 232 BAR. The AL80 would not be logical.

Advantages of steel 12l over AL80
Cost. Steel 12l is cheaper (in UK)
Weight. Steel 12l is lighter
Buoyancy. Steel 12l requires less lead
Gas volume. Steel 12l holds more gas

The only advantage I see is its use as a stage cylinder. This is diving the OP stated no to.

Not saying that a steel 12l would be the best for the OP. Just that an AL80 wouldn’t.

 

[R.Chisholm]

This forum provides so much useful information, it's incredible. But I couldn't find anything in regards to different setups for recreational diving. I'm not sure if the question is stupid Let's try. This will be a lot of text from my side and I'm wondering how experienced divers would rate the different setups.

My scuba background:

• I'm an AOWD with about 60 dives - most of them the typical holiday/tropical dives. I did and like more advanced dives such as diving in currents, night dives, entries of a cavern (no caves). Though I enjoy diving in the "deeper" region for rec divers (let's say 20-30 meters), this is not something I pursue to dive deeper, just to be deeper as anytime before. I like taking some pictures or videos of the dives, so I usually have some additional equipment with me.

General intention:

• I want to dive (more or less) full year in local rivers and lakes. Water temperatures varies from 4°C to >20°C, of which May - October (including) are above 10°C. Only January and February are below 5°C. I have no intention to dive at those temperatures.
• Pure recreational diving. I have no intention to do extra deco stops, use mixed gases, go below 40 meters, dive into narrow caves, or start using rebreathers. I do think that all of that is spectacular and would do that in another life but diving should be fun and easy for me. This does not mean I don't want to use technical stuff for diving - in fact I love technical stuff and I'm willing to invest training, money and time just to use the technics, though not at the limit. It's like to have a decent sports car: You can accelerate and brake faster than the others and the cornering speed is higher - but you don't have to drive at the limit to have fun (i.e. 1 km/h faster and you crash). Yes, waste of money for the potential of the car, but still so much fun.
• I don't have any issues with back, knees etc., I'm tall and strong, so moving dive equipment around, regardless the configuration, is very easy.
• Safety is priority number 1. Only diving with a buddy (or in a small group), never single.

Questions:

• 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":
  • Single tank.Let's say 12 liter tank. 2x valves, 2x 1st stages etc.
    • Most simple set up. If free flow occurs, closing the primary valve should give enough air to either ascend normally or maybe use a little bit of buddy's air while ascending (depending how fast the valve is closed and how much air is left in the cylinder).
    • Dives will usually be limited by air supply, not by NDL.
  • Double tank. Let's say 2x8.5 liters or 2x10 liters. 2x valves, extra valve in between (manifold), 2x 1st stages etc.
    • More "advanced" setup. May give more dive time.
    • I'm not sure if this setup will increase safety at a free flow compared to a single tank? What could happen that this configuration is superior, i.e. the extra valve between the tanks?
      If I close (let's say) the right valve, is just the exit to the 1st stage blocked but air from the right cylinder can go to the left first stage? Or is the whole right tank shut off?
  • Sidemount. Let's say 2x7 liters or 2x 8.5 liters.
    • Most "technical" setup. May give that little "extra" to diving by just using it, though not really necessary. It's like using a dedicated espresso machine + milk frother instead of a fully automatic coffee machine. The espresso machine will give the same espresso/cappuccino, but the subjective taste is superior :-D
    • This setup should result in increased safety at a free flow: Just use the other regulator. Even if the easy-to-reach valve of the affected tank is not closed - the other should provide enough air to safely reach the surface.

I think the real questions come down to:
Is a double tank configuration in any case better than a single tank configuration for rec diving?
Or will the only question be: Go single tank or sidemount. A single tank is as safe as a double tank (my assumption) but sidemount adds the technical side and improves safety.

Looking forward to your opinions and any downsides/benefits I did not mention in above text

Hi,

Having dived a lot in this environment (& countries) I can offer the following recommendations:

A single 12 l tank is a marginal for a dive to 40m if you intend to stay there until your NDL time is exhausted. Add to that with most H or Y valves most people cannot shut off the valve on their own on a single tank config in case of a free flow (which should be a consideration in cold water - it has happened more than once to me). If you decide to get a single tank the min size is probably 15l and in my case it doesn't trim out well.

Back mounted doubles - with these (& providing you practice) you should be able to shut down a free flow on your own.

2 x 7l is still a bit marginal for a dive to 40m if you stay until NDL is exhausted - especially if you dive with several buddies who may have a much higher consumption and need air in an emergency.

2x8.5l will be fine for almost all people for a dive to 40m within NDL limits for a total dive time of 40 min or so.

2x10l is too heavy for rec diving but doesn't have enough gas for proper decompression diving.

2x12l will be more than sufficient for rec diving -when I use one of mine - i normally exit with well over 100 bars for a 60 min dive - however they are pretty heavy and many divers don't have the strength required for difficult entries and exits in this configuration.

I'd avoid all 300 bar tanks - in practice almost all of the LDS won't allow self-filling to 300 bar and in any case if you really want 300 bar cold in your tanks you will need multiple fills with intermediate cooling.

Finally sidemount - I see a lot of "sidemount" divers who have problems doffing and donning with dry gloves.

As to taking a pony or stage - if you ask me and in this environment (lakes, rivers) it makes sense as a bailout or decompression stage - less so as a bottom stage to exend bottom time on rec dives. Add to that a stage clipped as a traditional deco stage increases the resistance in water significantly.

regards,

Rory


Diving in rivers - a small single tank cold water config is best, make sure it is streamlined to minimize the risk of snaging anything. 2x8.5l possible - but overkill for most of our rivers.

 

[Wildsparrow]

Thanks again, everybody, for all the valuable insights.
Currently, I think I will go with a nice back mount doubles.
I see the point of a pony bottle when you have a backmount with a single cylinder, but needing new gear anyway, I can directly invest in a double tank wing BCD such as the XDeep NX Project.

Beginning next year, I will go to Hawaii incl. diving, and then I'll start diving in local rivers/lakes. I'll keep you posted

 

[NW Dive Dawg]

I didn't read this entire thread but it sounds to me like you might best achieve your stated goal with a back mounted pony... I dive a 19cf along with either a 100 or 120HP Steel for my primary gas. Since you are big and strong, and prefer shore diving, this may be a great set-up for you.

Keep in mind that my Pony is not at all a part of my gas management plan for any dive. It's fully on and charged and always right there for me in case of an emergency....

The one thing I do that may be a bit different from others is that I have a small 2in face SPG attached to my pony reg and hose so that I can easily confirm my pony pressure both before and during my dive.