Easiest Way to Dive 2 Separate Tanks?

[drrich2]

Hi.

Strictly a recreational diver, bit of an air hog (SAC runs around 0.65 - 0.75 cf3/min.) normally wearing a Sherwood Avid BCD, TUSA split fins, Atomic B2 reg. & no wet suit shore diving Bonaire. 6'1", close to 275 lbs., tend to get around 40 minutes to an hour on an 80 cf tank with average depth over the dive of 20 - nearly 30 feet.

I'd like to dive a pair of tanks. EAN 32. I'd like to do it with 'off the shelf' provided 80 cf aluminum tanks. As easy and 'off the shelf' as I can.

I've been considering a Hollis SMS 100 for side-mount. I'm a bit put off by the prospect of rigging the tanks. I bought a Dive Rite travel stage harness and worked with it and an 85 cf steel tank quarry diving. Needed to use a couple of hose clamps to make the lower strap stay put. Would be irritating to have to switch to different tanks often (say, 3 or 4 dives per day).

I'd written off doubles since manifolds and those metal brackets to bind 2 tanks into a single rigid unit looked like way too much hassle.

But I saw another thread where someone discussed diving independent doubles (no manifold) - more akin to side-mount in some ways, rather than traditional manifolded doubles.

So I wonder; what is the easiest way to dive 2 independent tanks? Ideally it'd let me mount tanks the same way a traditional single tank jacket BCD does; drop 2 regular BCD cam bands over the tank, clamp down tight and call it good.

Is something that easy a pipe dream? Is there a side-mount or doubles product that's that easy?

Thanks in advance.

Richard.

 

[Paul S]

Strictly a recreational diver, bit of an air hog (SAC runs around 0.65 - 0.75 cf3/min.)

Much the same sort of rate as me. I'm a big chap with big lungs. I use more air.

tend to get around 40 minutes to an hour on an 80 cf tank with average depth over the dive of 20 - nearly 30 feet. I'd like to dive a pair of tanks. EAN 32. I'd like to do it with 'off the shelf' provided 80 cf aluminum tanks. As easy and 'off the shelf' as I can.

Fair enough. I can understand that. What would you say your max depth tends to be, and how long do you stay down there? Do you want to do this so you can go deeper, stay longer, what? I ask because you need to be aware of your no-deco limit if you're wanting to stay longer at depth. It's very possible that you'll start hitting it.

I've been considering a Hollis SMS 100 for side-mount. I'm a bit put off by the prospect of rigging the tanks. I bought a Dive Rite travel stage harness and worked with it and an 85 cf steel tank quarry diving. Needed to use a couple of hose clamps to make the lower strap stay put. Would be irritating to have to switch to different tanks often (say, 3 or 4 dives per day).

Personally I use cam-bands (like you use on the back of your BCD) to attach the bottom of my rigging. That makes them fairly simple to move between tanks. It's even what the top guy at Dive Rite uses. A stage strap is something different. The rest of the rigging (attaching regs, stowing hoses, positioning clips) takes a little time, but it's the sort of thing you get quicker with the more you do, and you can do it a long time before you dive. It's not very different for independent doubles either. I just take a quiet moment to sort it out when people are off doing what they do. Five minutes before hand and then when everyone else kitting up all you need to do is put your harness/mask/fins on. Clip the tanks on just before you jump (or have them handed to you in the water) and you're away.

I'd written off doubles since manifolds and those metal brackets to bind 2 tanks into a single rigid unit looked like way too much hassle.

You won't move a manifold between tanks. It's (almost) permanent, as are the steel bands if a manifold is in place. The bands ensure the tanks don't move and bend the manifold. You're right. It's not what you want.

But I saw another thread where someone discussed diving independent doubles (no manifold) - more akin to side-mount in some ways, rather than traditional manifolded doubles.

Some BCDs allow using double cam-bands to join two tanks together. Depends on the BCD though. I'm only aware of Buddy providing a system to do this, but maybe there's more.

Otherwise I tend to see people using independent doubles by using those steel bands and a backplate + wing. Not exactly a 10 second job to move between tanks. It's a case of undoing bolts. Fact is, when most people are diving doubles, they dive their own tanks, and it's all put together permanently.

As far as the diving technique goes - side-mount is independent tanks on your side; back-mount they're on your back. Sounds obvious, but what I mean is that you need to do the same regulator switches, gas management, etc. All that changes is the location of the tanks. That changes some skills, but not much.

So I wonder; what is the easiest way to dive 2 independent tanks? Ideally it'd let me mount tanks the same way a traditional single tank jacket BCD does; drop 2 regular BCD cam bands over the tank, clamp down tight and call it good.

See above. To quickly move between tanks I think you're looking at side-mount or cam band based back-mount. Either is going to need a BCD/Wing that supports it. I think you've got more options going side-mount. Back-mount is good, but tends not to be for travelling IMHO.

 

[redacted]

The easiest way, especially in Bonaire, would be to simply sling a 2nd tank - either an 80 or a 63. The rigging would cost about $20 and it would take 10 or 15 minutes to transfer from one tank to another. For many Bonaire dives, an hour is probably enough but when you want a bit extra, adding a slung tank will do it cheaply and easily. Well, easy if you make two trips - they are a bit heavy and awkward out of the water.

 

[japan-diver]

The Dive rite travel stage kits should not require a hose clamp to stay in place- I have used them on 80's, LP85's and 120's with no problem - they take about 1 minute to change between tanks. These with a sidemount kit would be the best way to go to two tanks. If you are looking at 80's the Nomad LT from Diverite is a great rig for that.

 

[scuba127]

I also almost exclusively shore dive Bonaire. I used to sling a tank but have now gone to Sidemount for two tanks....trained on SMS 100 but am now prepping an SMS 50 for diving aluminum tanks in a wetsuit. If the ideal situation for you would be similiar to single tank back mount, then I'd say back mounted independent doubles. I few years back, I talked to Tobin at Deep Sea Supply about this configuration and, unless something has changed, he has a back plate wing system that is designed for back mounted independent doubles. You might consider giving him a call.

 

[DevonDiver]

2x Cam Bands. 2x Bolt Snaps. 2x Tri-Glides. A hand-full of 1" rubber bungees (cut from an old car tyre).

1 minute per tank to set up.

Add to a Hollis SMS100... and you've got a very convenient, quick and comfortable way to dive doubles..

 

[drrich2]

Thanks for the info. Some followup:

Paul S.:

What would you say your max depth tends to be, and how long do you stay down there? Do you want to do this so you can go deeper, stay longer, what?

My typical dive plan is walk out to waist deep, don fins, swim out to reef drop off, turn to the side, north or south, into the (minimal current) and swim parallel to shore at around 40 feet deep, drop to around 1600 - 1700 PSI, signal my (lean, short, air-sipping) buddy, then head back at around 20 to 30 foot depth, but I may 'swoop down' to look at a wreck, interesting animal, etc... So my dive computer profile may show a max. depth around 50 - 60 feet, average depth 25 feet, with most of the depth earlier in the dive. Out of 22 dives late August in Bonaire, my max. depth was diving a tugboat wreck north of Eden Beach Resort; I hit 91 feet.

I want more bottom time. Diving EAN 32 in Bonaire I'm mindful of my dive computer, but even diving 3 or 4 times per day generally get nowhere near my NDL.

Personally I use cam-bands (like you use on the back of your BCD) to attach the bottom of my rigging. That makes them fairly simple to move between tanks.

Are these cam bands free of your BCD? Is there a product page pic I can see to visualize this?

Awap & Japan Diver:

In our local quarry, I've used the Dive Rite travel stage strap on an 85 cf steel tank to provide a redundant air source for an SDI solo course. By putting 7 lbs. weight in my right pocket and none on my left, yet clipping this on my left, I think I 'trim out' decently well and don't seem to roll. But that strap the bottom bolt snap is attached to tends to 'ride up' on me. If it rides up enough, it can come undone.

The reason I added 7 3/4" hose clamps (ordered off Amazon) was to put one down low and secure the bottom portion. One would probably do fine. It works! But it involves using a screw driver to tighten and loosen, and that bit more hassle. Diveable, though (& I loosen the clamp before I have the tank refilled).

I see Leisure Pro has the SMS 50 on sale at a really good price. What bugs me is that I've read with side-mount rigs there's considerable 'messing with' the system to individualize it so a diver trims out well. I'd like to take a side-mount course; been looking for someone locally.

Scuba127:

If the ideal situation for you would be similiar to single tank back mount, then I'd say back mounted independent doubles. I few years back, I talked to Tobin at Deep Sea Supply about this configuration and, unless something has changed, he has a back plate wing system that is designed for back mounted independent doubles. You might consider giving him a call.

I'd like to see that setup in action! The main concern I have (and you can find something wrong will almost anything!) is that shore diving through the iron shore and rubble of the shallows, falling with 2 tanks on your back might be worse (of course, falling in side-mount and coming down teeth first on a first stage probably isn't a cake-walk either...).

Thanks again for the input, guys!

Richard.

P.S.: DevonDiver posted while I was typing my reply. I'll have to take a look at that; thanks!

 

[Paul S]

At that sort of depth you're going to have to be down for a LONG time to hit NDLs.

The double cam bands I mentioned : CAMBANDSBuddy Twinning Bands - Divernet

...but shore diving (I hadn't realised) I'd really be side-mounting. Two tanks on your back are heavy, and I'd rather move stuff about one at a time and put them on in the surf.

 

[Colliam7]

I want more bottom time. Diving EAN 32 in Bonaire I'm mindful of my dive computer, but even diving 3 or 4 times per day generally get nowhere near my NDL.

Of course, you could increase the number of dives/day, from 4 to 6, to get more bottom time. Seriously, only 3-4 dives / day? Gotta work in a night dive, and a 'night to dawn' dive to get that number up to 6. That way you do one before breakfast, two between breakfast and lunch, two between lunch and dinner, and one after dinner. You will sleep well (I certainly do).

What bugs me is that I've read with side-mount rigs there's considerable 'messing with' the system to individualize it so a diver trims out well.

There is not necessarily more 'messing with' a sidemount rig than a BM rig. Perhaps, the reason you have heard / read that comment is that there IS greater flexibility in tweaking trim with a SM rig. Of the two, and I dive both, for flexibility I MUCH prefer the SM. With BM rigs, is it more WYSIWYG.

I have taken my sidemount gear to Bonaire three times (although, I didn't even dive it this last time). It is SO-O-O easy - takes all of 45 seconds to rig a tank, or change tanks.

The main concern I have (and you can find something wrong will almost anything!) is that shore diving through the iron shore and rubble of the shallows, falling with 2 tanks on your back might be worse (of course, falling in side-mount and coming down teeth first on a first stage probably isn't a cake-walk either...).

With SM shore dives on Bonaire, I don't even try to clip my tanks on before I get into waist deep water, even if I have to take one in, drop it, then come out and get another. I have enough trouble negotiating the entry at some of the southern sites with a single tank. Now, on Karpata, as one example, SM is easier - rig your tanks, and carry them down the steps, and put them on top of the concrete pier (unless the water is up and there is a lot of surge across it). Standing on the right side of the pier, you can clip them on, and away you go. On La Dania's Leap, carry them down to the entry rock, then clip them on, and do the giant stride - what a gas!. Of course, you still have to take them off at Karpata and rest them on the pier, to get out - at least I do.

 

[JamesK]

Personally i fell if two tanks are going on my back, I am going to have them manifolded. I simply will not do back mounted independent twins. To me it sounds like your best solution is a stage bottle or side mount. You stated that your band tend to ride up. It sounds like your cam band was not tight enough, or of poor quality. Try getting the cam band wet first to allow stretch. If you did that, consider a new cam band.

Sidemount tanks are very easy to rig up. Just as quick as a standard bc tank change IMO. If it takes longer then five minutes to change both tanks, then you are not holding your tongue properly.

What Sidemount rig to buy is the question. What type of tanks do you plan on using? Wetsuit or dry suit? Cold or warm water? I ask because if you are diving Al80's in the tropics then soothing like the SMS 50, UTD Zwing, or Dive Rite Nomad LT would work great. if you are diving dry with somei like Faber 85's those would work as well. if you are diving heavy steels you will want the lift from something
like the SMS 100, The big UTD wing, the Manta Industries setup, or a larger Nomad. A proper Sidemount course will be beneficial but you can do it yourself.