ustom Divers 66lb Dual-Bladder TDB wing, mounted on an Oxycheq ‘Ultralite’ soft travel backplate with single-piece hogarthian harness.  The rig is completed with an OMS ‘Profile’ sidemount adapter – this is a convenient option for preventing wing taco and providing a butt plate for mounting ancillaries/stowing kit.

The Custom Divers TDB wing for Sidemount Conversion

The Custom Divers TDB wing is well suited to this conversion.  It has a redundant bladder and the low-pressure inflators are sufficiently off-set on the shoulders so that they aren’t occluded by the OMS Profile adapter (the adapter can cover and obstruct LPI/OPV if they are mounted to centrally at the top of the wing.  From what I’ve seen, only the Custom Divers TDB and OMS Tesseract wings have sufficiently spaced LPI/OPV to achieve a snug fit with the Profile adapter.  It provides 66lbs/300nm of buoyancy, which is more than adequate for most multi-stage, mixed gas deco diving requirements.

I exchanged the back-up low-pressure inflator (LPI) from the top-left shoulder down to the bottom left OPV on the wing.  I now use this as my primary inflation.  The pull-dump/over-pressure valve (OPV) now mounted on the top right shoulder is convenient for dumping, even in horizontal trim.  This modification keeps my primary inflator routed consistently with my other sidemount rigs – and remains ideally located to connect with a short LP inflation hose routed from the end-port of my left-side/primary sidemount regulator.

Custom Divers TDB Technical Wing Trimix Diving Philippines

An old photograph of the Custom Divers TDB in it’s previous guise as a backmount doubles wing.

The former ‘primary’ bladder inflator is now the back-up.  This remains routed from the top left shoulder, but is bungeed down the side of the wing (behind my shoulder).  The hose is sufficiently long and flexible to bend out beneath my arm and mate with the LP hose when it is needed. It also reaches my mouth for oral inflation, without needing to be removed from the bungee that stows it. I don’t dive with the back-up inflator connected. The back-up wing OPV is on the lower right of the wing and easily accessible.

In conjunction with lateral D-rings provided on the OMS Profile adapter, I have used 3mm bungee to ‘shape’ the wing for effective sidemount trim.  I restrict the top of the wing, but leave the lower half more unrestrained.  This not only keeps the wing snug (it doesn’t extend out beyond the width of my torso) but also shifts the buoyancy lower towards my hips – which is the ideal location for lift when sidemount diving in horizontal trim.


Detail of the Oxycheq Ultralite soft backplate configured with single-piece ‘hogarthian’ harness. It bolts to the wing and Profile adapter using low-profile bolts.

The Oxycheq Ultralite Travel Backplate for Sidemount Conversion

I opted for the Oxycheq ‘Ultralite’ backplate because I reserve concerns about the suitability of metal backplates for use in confined space wreck penetrations.  It would be too easy to ‘wedge’ a metal backplate into a tight space.  The Ultralite backplate solves that problem, whilst still permitting the clean and consistent use of a hogarthian style single-piece harness approach. As mentioned, I feel it is important to retain consistency between all of the rigs that I use.

The Oxycheq Travelite is the lightest option currently on the market, weighing just 257 grams.  Another option would have been a Zeagle ‘Express Tech’ soft backplate (it’s longer, so possibly better for those with longer torsos) – but I couldn’t find those available to buy in my area.

diy sidemount technical diving rig bcd harness system

The OMS Profile Adapter for Sidemount Configuration

The OMS Profile Sidemount Adapter was designed to mate with the OMS Tesseract Wing to create a simple conversion between sidemount and backmount.  I’ll be honest, the connections/mounting is very specific to the Tesseract, so some ingenuity and perseverance needs to be applied to make it work with other brands/models of wing.   I needed to use extra lengths of 1″ nylon strap to make it work with the Custom Divers TDB.  A few hours of finickety struggle, a few tired fingers and some choice expletives… and it all assembled rock-solidly.


Detail of how the OMS Profile sidemount adapter extends around the top of the wing. To fit with wings other than the Tesseract, you need to splice the two 1″ nylon webbing loops with an ‘extension’. If the LPI aren’t offset at the top of the wing, this cover will obscure them.

You could, of course, just buy a Tesseract BCD to go with the profile, but my aim was to convert the equipment I already owned.  I’ve had the Custom Divers TDB for over a decade and it had been relegated to a plastic crate under the stairs for several years, so why not make good use of it?

OMS… if you’re listening… it’d be great if you could refine a version of the Profile for use as a generic adapter for any model/brand of wing.  Just a few changes…  I’d be happy to help you with that. 😉

The Profile also features a ‘wrap-over’ protector for the top of the wing.  That’s a great idea for providing some serious abrasion resistance when conducting ‘squeeze through’ penetrations.  However, the ‘wrap over’ will obscure the LPI on many wings.  The Tesseract wing is designed with this in mind – and off-sets the LPI further out on the shoulders.  Luckily, the Custom Divers TDB also had sufficiently spaced LPI to enable a clean mating.

diy sidemount homemade diving technical equipment

I previously used the OMS Profile sidemount adapter with a 30lb ‘donut’ single-tank wing. It worked well, but my dedicated lightweight minimalist rig works better. With a double-bladder technical wing it offers capability for extreme dives.

One useful feature of the Profile Sidemount Adapter are the 3 small D-rings located down each rear-side of the adapter. This enabled me to route some 3mm bungee around the wing to help shape the buoyancy profile.  I think the original concept behind those D-rings was for bungee attachment – but I like the function they provided me.  Normally I wouldn’t be a fan of bungeed wings – but for this type of sidemount conversion it is very beneficial to restrict the wing shape and maximize buoyancy retention at the tail.

The Profile Adapter includes an integral butt-plate.  My first modification was to reverse the ‘rails’ onto the underside of the plate.  This makes the rails easier to locate (sounds more difficult, but isn’t) and prevents them becoming an entrapment hazard in tight spaces.  Butt-plate mounting is more synonymous with cold-water/steel cylinder sidemount diving. However, I do actually find these a good initial connection point for aluminum cylinders too.  As they become buoyant, I move them onto low profile D-rings on the waist belt to retain proper cylinder trim. That’s odd, because with other wings (such as the Hollis SMS50), I find the butt plate to be a very inefficient mounting location for aluminum cylinders.

My only other modification was to add a D-ring where the crotch strap originates and also tie some loops of bungee across the butt plate to enable convenient stowage of a large DSMB/Lift-bag.


Total Cost:

  • Oxycheq Ultralite Backplate:  $80
  • OMS Profile Sidemount Adapter: $100
  • Custom Divers TDB Wing: used existing/already owned
  • D-Rings and Clips: $55
  • Crotch Strap: $15
  • 6mm Bungee: $8
Rig made for: $258.00

If you need any advice on configuring a DIY sidemount rig, please feel free to contact me.  I also run frequent clinics to help tailor and tweek your sidemount for optimum performance.  Of course, I also provide formal sidemount certification training also – offering the PADI Sidemount Diver, TecRec Tec Sidemount and ANDI Sidemount courses.

DIY sidemount technical wreck diving philippines

What Others Are Reading