SBOD History and Teardown

How to Steal Your Very Own Rebreather
SBOD History and Teardown
By Digger


Now, I started all this rebreather business partly out of offering to safety cover anyone who I thought silly enough to dive one of these death traps, and very soon became an addict. On the first day I’d come down to help out John Routley narkedat90.co.uk with a bit of testing, Duncan Price gave me a piece of gas pipe and some end caps, and told me to use it as a scrubber, make my own P1SS. Those of you who’ve not seen the P1SS have a look at Duncan’s website at sump4.com , it’s very interesting, and a great way of getting to understand RBs a bit from the sharp end. Thanks go to both the guys above for getting me started, and for their continued help with all manner of crazy ideas. I don’t know anyone who can get things done and come up with solutions to problems like John, and I don’t know anyone quite as unhinged as Duncan (and that’s coming from someone widely considered to have lost it a bit too!) so this made for a great Rebreather philosophy. If you want it you can get it, and once you get it try it and find out if it works. I have developed a lot of respect for these guys amongst others who do what I have done a lot, and who have changed the way I dive completely. Nice work boys.

I started off with a nice little unit, which did the job for a few dives, made from Duncan’s gas pipe jobbie and an ABLJ, no monitoring, and oxygen only (for obvious reasons!). I soon outgrew this, but not before I’d done 5-6 hours on the thing, including one seat of the pants hour-long dive, which was quite scary at times, but proved that it works in practice, so I can’t have made too many errors.

Then I moved on to the Digspiration. It was nice, and used 2 x 2l tanks on the bottom, with a Drager Atlantis scrubber on the top, and Inspo lungs, as well as the customary SS plate and wing etc. The O2 was added to the loop KISS style, but using the Swagelok bits to do it, as well as a shut-off ball valve. Worked well, but it gurgled, and the scrubber was shite. I mean shite. I’ve seen some badly made stuff in my time, but this thing I wouldn’t sell on eBay for fear someone else might use it to top themselves. I’ve since sold it on eBay. It leaked, it warped, the gasket came out altogether the once, and it was fragile and not great from a design point of view anyhow. So it needed replacing. Here’s where John got really useful. He lent me a Drager FGT scrubber, a vertical stack with dip tube down the middle, which was made a million times better, despite being made a few years before the Atlantis unit was released! Why Drager didn’t use that I’ll never know. They’d have a lot more people converting units to CCR or could quite well have done it themselves.

So, once I’d got the scrubber that no longer fitted with my plans I needed a case, or some way of putting it all together. I was nearly set on buying an Inspo case as it would fit everything just nicely, then I thought about an Evo case because of the convenient size, but then I went off to the South coast to dive the Mexico with Kinky Divers and among them Mdemon. Now he had a barbecue (as it’s been named now) which Andy Hayhurst has custom made for Inspo setups. I thought that was the answer for me. It’s simple, it works, and he has a large (7l steel I think) and small (3l steel) tank on each side, giving him bailout and loads of gas for all sorts all in one place. Nice. I liked the look and I liked the idea of it. So I started discussing money. £200 is about the cost of a BBQ, depending on clamps and extras etc., so I started to consider a better (read cheaper) way of doing it.

All the units so far have been needle valve units, simply because I don’t understand or trust electronics. I don’t get solenoids and voting logic, I have all the logic I need in the vital 6” between the ears. I just need to know what I’m breathing and I’ll do the rest. Too many computers have crashed for me to trust software.


Now on to How to Steal Yourself an Rebreather

What you will need:

1. A girfriend
2. A branch of Tescos (big supermarket chain for anyone outside the UK!)
3. Some shopping that needs doing

It came to me like that guy on the road to Damascus. Wasn’t it Steve? Or Maybe Pete? Oh well, on with the story. A shopping basket. It’s the perfect size (I mean perfect, the scrubber is 28cm at its widest, and the basket is 30cm deep) for the scrubber, tanks, and for me too. They are also free, unlike the trolleys that they charge you a pound for. A pound! For a trolley! They’ve got to be worth more than that, but there we go. I considered that if they didn’t have a slot for my pound, they could spare a few. So the good lady and me went stealing for the day. We freed a basket from the shackles of Tesco, and it’s much happier now. You can tell, it sings when you bend it and things It also has convenient holes in it so any leaks are clearly visible, and perfect for sticking a jubilee clip through so you can mount tanks, torches, argon bottles anything on there. Oh, and they’re easy to cut too – the thin wires you can do with wire cutters, and the thick ones were no problem for the Scorpion. Thanks to Black & Decker.


All the Bits You Need to Make Your Very Own SBOD (Shopping Basket of Death)


From the top left: Lean OC bailout reg (Aqualung Arctic) with wing inflator hose, basket and tanks attached, dil Poseidon 1st stage and inflator hose, Rich OC bailout (Apeks TX50 on MK2 1st), SS backplate, Argon tin, Scrubber and hoses, OMS wing, O2 1st stage attached to counterlungs with custom ppO2 monitoring attached*, Drager Ray mouthpiece and hoses with Inspo fittings.

(*The housing for this was designed and made by John, and he sold me this lovely bit of kit when he redesigned this, and uses 3 K1D cells mounted in a P-port. Details of this are in the gallery. I’m told it’s a Mark Munro circuit board, and does the job)


Now to the Strip Down


This is the basket with the tanks attached. I have used a steel 40cf on each side, and the 2 blue tanks are 2l ally tanks. I am a great believer in using what you’ve got in building units, as you can see by the use of a piece of wood for the bottom bracket holding the basket to me. It’s not taking much weight, and I feel wood is a material much under-used in diving equipment. If there was more wood then divers would float a lot more, and we’d see a lot less incidents at the surface IMO Before I get a load of e-mails, I’m kidding ok!

Now here the tanks are as close as they can be because the first stages have to fit between them. It means the larger steels rely on the thick wire around the edge of the basket, but that’s not going anywhere in a hurry! The smaller tanks are banded onto the bottom 2 wires around the basket and are very stable indeed now. Which is good, as they drive the unit. I wanted them as close to me as possible, as reaching round is not easy. I have them now in a position where I can get to them easy enough, I just have to lean a bit and they’re right there. There aren’t a lot of situations I need to turn the thing off for anyway, I have a shutoff for the needle valve if that fails, and the inflator buttons are on quick disconnects so easy enough to remove. But it’s nice to be able to if you need to!

The belly of the beast, and showing the current attachment method. This is going to be replaced with a SS plate just as soon as I get the time to measure it up and pay for a piece of metal!


At the moment, the steel 40s are my OC bailout. In the right hand tank is 80%, which I have come to like recently as a get out of the water fast gas as well as being able to drive the unit manually wasting little gas using it. The left tank is air (at least for now, until this thing is ready for Rebreather Trimix diving) which also feeds the wing. This way I have separate sources for all my buoyancy. Unit from the 2l only, suit from the argon bottle, and wing from the 40 with the bailout. Works for me, and gives me total redundancy.

The basket did need some modifications. As you can see in the photo holes are needed for the breathing hoses. These are easy to do, you just need to watch you don’t break any welds on the basket unnecessarily, as this is what’s holding it all together!


I have used Inspo hoses from the scrubber to the T-pieces, and ray hoses from the T-piece to the DSV. This was again a use what you have solution, and works fine for me, as well as being the same size anyhow. Only problem I have is with the Inspo fittings which I have grown to dislike a lot because they’ve caused us a world of problems. To get them off in the end we gave up and got the hacksaw out the other week. I’m tired of using them, and they do very little a cable tie doesn’t. So now, I use cable ties where necessary. Plus it gives it a good homemade look.

The Ray mouthpiece is upside-down. We had a Drager Lar-V mouthpiece which did the job, but the fittings we used gurgled and weren’t great, so I just plumped on buying this thing, which is ok. The reason it is upside-down is the direction of gas flow is not reversible with Drager DSVs like this, and the O2 injection etc is all on the right and setup how I like it. I work on the basis of rich on the right lean on the left with everything – tanks, hoses, gauges, stages. Means I know what’s what in the dark guaranteed. You’ll also see red and green tape all over the thing, that’s not Port and Starboard for navigation, its dil and O2 and lean and rich mixes respectively. High O2 is green, low O2 red. Covers all the bases for me.

This side view gives you a decent view of the hose setup – very normal and standard Inspo type:


We also, much to my dismay, had to remove the handles. I wanted to find a use for them, but maybe on another project. They weren’t very strong, and came off quite easily once they’d been attacked a couple of times with a hammer. The eyelets from the handles were extremely useful though, and were bent in to make the mountings for the backplate. Worked very nicely as they fit M8 threaded rod just right. Nice. Without the eyelets attached it would have been difficult to mount the plates securely, and the plates now also add a lot of structural strength as I thought they would.

The basket admittedly is wider than it needs to be. But that’s ok, it’s only a few inches too wide in all, and to be honest compared to the size of me and the tanks it’s nothing. And it gives me somewhere I might hide things like a nice packed lunch for a long day out on the boat, and I was thinking maybe an EBIRB and a waterproof box for a pack of fags. Mind you, if we’re lost at sea that long I’ll need some food and water too. OK, the space won’t be wasted. After a few dives, I’ll see if I can get my hand in there, in which case might be a good place for backup gear like SMBs masks etc as it is very very well protected in there. This photo shows the profile of the unit from the top:


You can see it could be a bit smaller, but not a lot. Once the tanks are on there it’s going to stick out just as far, so the only benefit is the width.

The only other plus for the basket was that the wires on the outside all run vertically, so any obstruction or lines etc will not get caught, hopefully will just slide off. Should be fine. And it slides good too for getting down boardwalks to boats etc. and from Stoney Cove’s top carpark!


Now, important stuff – how the unit works. It uses a Swagelok needle valve in a KISS stylee which is very good as a system. Why people would spend huge amounts of money on fancy KISS valves I’m not sure, as this has worked absolutely fine for me. It’s mounted on the inside edge of the counterlungs so I can get to it if it needs adjusting, and also the shutoff valve is right there too. By chance, the shutoff valve is placed perfectly – if it’s off it sticks right into my collarbone, so little chance of me getting in the water with it turned off! Not likely with all the pre-breathe and stuff, but possible, and this helps it not to happen.


You can also see the clever use of a Buddy A-clamp crack bottle fitting. This has been tapped out to fit the 1st stage end of a Buddy reusable hose end (I love these things) and works well. It also uses a hole the same size as the Buddy inflator buttons, so when it comes to selling or if the unit takes a different track I can just put another button on there, and you can get blanks for them easy enough too. I try not to make permanent mistakes with my units, as once its cut you can’t really stick a lot of these things back together!

In case you were wondering, it’s just a standard harness underneath the lungs, on a Combro SS plate. Nothing revolutionary there, but this would work with any harness or plate combination. The lungs are normally attached to the plate through the holes the webbing goes through, and this works fine for me, but I might change this a bit in the near future as it can be a pain looking for the short bits of webbing to clip the lungs down.

The size of the thing is a bit of a drawback, but as far as I can see this is a unit good for deep diving, and the boys seem to think you’d be ok down to 80m area with the bailout on board, and to be honest I wouldn’t have any problems with clipping on a couple of stages on the front other than a distinct shortage of 1st stages and tanks! That said, I do have a couple of 12s knocking around…

I like what this unit is capable of, and I learned from the first unit I built. If you scrimp and save in the wrong places you’ll cost yourself just as much again changing it for something better. Spend money when you need to and you’re fine, and don’t forget the mates who helped you out along the way. I try and help them where I can but to be honest they’ve got just about everything! Oh well, if anyone needs any help from me any time just let me know.

Just out of interest, so far, rebreathers have cost me a thousand pounds, and I’ve now built 3 units basically using bits from other units before and using off the shelf bits as well as custom made parts. Those that tell you it will cost you more than to buy one off the shelf didn’t have the advice I did early on, nor the help that is being lent components and parts. For that, I am grateful, but it’s something I’d happily do for others, so anyone who wants to play with a Drager Atlantis scrubber let me know. I think you could get an entire unit in a basket if you used one of those and 2 x 1.5l tanks!!!


All questions, comments and suggestions welcomed and encouraged. If you know how this unit would be better, I’m all ears, because I want my gear to be the best I can make it. So far, the basket is doing just nicely. When I’m feeling rich, I might go buy a trolley for a pound and make something nice in that, one of the shallow ones designed for single people and families who can’t afford to eat a lot.

Hope you’ve enjoyed this little jaunt through the strange world that is my unit, come again sometime. More mods to come, just waiting for new ideas. ADV likely in the next few months methinks, we’ll see. So far, I’ve not needed it at all, and I like learning without it so I won’t rely on it when I have it.

PS – Cheers Stuart for providing somewhere to host articles and photos like this, and giving us the space we need to play.

Edit 29/03/06: I have since gone on to use the unit with a slightly different case (the NDC objected to me diving using a shopping basket as a case, something about negligence and the way it looks for them etc) so I got a stainless case made up, know affectionately as the dig shit bin or the cheese grater of death. The unit in this form went on to do two 85m dives in Dorothea, and performed flawlessly throughout.

Unfortunately, I now need a unit I can get training for. Despite nearly finding a way to get qualified on the unit (the manufacturers training course was something I looked at in some detail!) I ended up going for a KISS. It works in the same way, but cleared up my chest area and was generally better made. It would be, I don’t have a machine shop.

If anyone wants the shopping basket, it is now available for sale, for only $19.99 plus shipping. Bear in mind you can get them for free in your local shop.

I hope some of this is of entertainment value, and possibly of interest

Digger


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