My own favourite way of diving is sidemount. This is how I do it.

Using the System
I start with the left hand bottle, unclip the regulator and breathe it until it is time to switch. To switch, clip off the second stage and put the other one in the mouth, with the lanyard attached.

Gas Management
Use one third off the left, switch, use a third off the right, turn the dive, use another third off the right, switch and use the second third off the left.

Identifying which bottle is being used is easy - it is the one whose gauge is moving! Otherwise, just shut down one of the bottles and see if you can still breathe. Do not forget to switch it back on!

Emergencies
- Leaks/Freeflows: whichever valve, simply shut it down. The leaking regulator can be controlled by turning the valve on and off just long enough to take a breath.

- Out of Air: switch to the other bottle. With the right gas management there will be enough to safely exit. If you need to, connect the spare inflator.

For a total gas failure, grab the regulator which your partner is breathing. The right hand regulator will pull free from the lanyard, the left clip should be a break-away connection. Once the situation has calmed down, exchange one of your empty bottles for one of your partner's.

Why Use Sidemounts?
- narrow cave passage
- anywhere there is walking or climbing (better placed centre of gravity)
- passing sumps where dry caving gear must be carried on the back in a tackle bag
- diving in remote areas where carrying a manifolded twinset would be logistically difficult (Ox Bel Ha and Nohoch Na Chich projects in the Mexican jungle)
- solo cave diving (all the benefits of independants but fewer problems)
- reduced drag
- easier access to all equipment

Return to Equipment page

Harness
The basic harness is either a diving harness like the Dragon ASM or a standard backplate and harness. The harness should have waist d-rings either side and shoulder d-rings either side.

Cylinders
Two are required. I prefer steel because the weight eliminates the need for extra lead. Rig them like stage bottles as described here. Each should have two loops of inner tubing or bungee cord. Orientate the clips so that the bottles hang with the knobs pointing outwards. Each bottle is clipped to either side of the harness.

Regulators
This system uses any regulator: left handed or non-handed regulators are not needed. The right hand regulator has a second stage on a normal length of hose, a gauge and the drysuit hose. The left has a second stage on a 1m hose, a gauge and if a wing is used then it should have a LP hose, else a hose which will fit the drysuit. There should be a bolt snap near the end of the regulator hose.

The right side regulator has the gauge looped into bungee around the neck and turned so it faces upwards. The suit hose runs under the harness straps to the inflation valve. The regulator hangs in a bungee loop around the neck.

On the left, the gauge is looped into the neck bungee like the right bottle. The regulator hose runs up and over the left shoulder, across the back of the neck and round over the right shoulder. Clip it off to the shoulder d-ring. If the LP hose is not in use then bungee it in place.

If the bottles are to be removed then put all the hoses in the bungee.

Primary Light
I use a standard AUL Spectrum 14 cannister light. It is worn on the right waist as normal. The waist d-ring is threaded on in front of it and holds it in place. Clip the light head to the shoulder d-ring. The light can be removed by unclipping the bottom of the right bottle and by sliding it over the d-ring. The bottle is not completely removed so buoyancy is not affected.

Back-Up Lights
Attach them to the shoulder d-rings and bungee in place as normal.

Reels
I attach reels to the rear d-ring on the crotch strap as normal.

Helmet
If dry cave will be encountered at the end of a sump, then a helmet is essential.

Buoyancy
Buoyancy comes from the drysuit but if a wetsuit is used then a wing can be added. Wear the wing inside the backplate, i.e. between the backplate and the diver. This stops it "flapping". Dive Rite's BCD Junior wing is useful because it has clips at the bottom to stop the flapping effect.

ABLJ/horse-collar BCD's also work quite well because of the different centre of gravity.

Whichever option is used, put a short sleeve of inner tubing along the corrugated inflator hose and run the LP hose from the left-hand regulator inside it.