Thursday, 3 April 2008

Why we wear our stages on the left

Taken from an original post by Hassan on I thought this was an excellent article on the reasoning behind having multiple stages on the left hand side.

Our standard switching procedure includes the following steps: Signal to switch, cylinder is prepared, diver checks markings and depth, buddy checks cylinder markings and depth and gives ok, diver then switches, confirming switch to team. What this sequence entails is that any particular placement of cylinders plays absolutely no role in choosing which cylinder we switch to. Therefore any richie-righty lefty-leany or any other similar rules become irrelevant.

Now, on to our reasoning behind having cylinders on the left. First, let's take a quick look at some of our gear and think about how it all comes together:

[*]Our stage/deco cylinders are exclusively aluminium, not steel.
[*]On our right hip we carry the canister of our primary light.
[*]Our long hose is our primary hose, ie we are breathing from it. Hence it goes over our right shoulder, under the light canister on our right hip, diagonally up over our chest, around the neck to the mouth.
[*]Our primary light head is carried on the left hand when deployed, and clipped off on the right shoulder d-ring when stowed.
[*]Our stage/deco cylinders have a regulator fitted with a 1m hose (more on that in a tick)
[*]We have two shoulder D-rings, one on each side.

Now, to elaborate on the above list point by point:

Since we use exclusively aluminium stages, we can never be so off balance that it becomes a serious comfort issue. On our left side we clip a maximum of 2 cylinders, with any additional ones being attached to a "leash", which puts them more or less centrally positioned on top of our backside when full, or when empty floating gently out of the way. We know from experience that aluminium stages, even several, when used correctly do not make a diver unbalanced.

The canister light on the right hip is convenient, since it provides a comfortable way of holding the long hose in place, its weight provides some balance to our gear, and its position on the right, non-buckle side of the strap means it can be easily ditched in case of a bouyancy emergency. There really is no room for a D-ring, and even if we were to add one in some awkward way, a cylinder on the right side would probably cause damage to the canister or the cable coming out of it.

The way we route the long hose achieves several things: It is easy to quickly donate to our buddy in case of an OOG emergency, the hose is kept out of the way, the hose is unlikely to come loose when we don't want it to, and it won't get tangled or entrapped in other parts of our gear. A cylinder on the right side is incompatible with our long hose routing. The long hose would inevitably become trapped by the cylinder, making gas donation a very complicated maneuver.

The primary light must be easy to deploy and stow during the dive. There should be no entrapment of it, and we must be able to manage it while donating the long hose in a gas emergency. We can't have stage rigging getting in the way. When stowing or deploying the primary light we don't want our right d-ring to be cluttered.

The stages are equipped with a 1m hose so that we can wrap the hose around our neck just like the long hose. This fullfills two functions: The hose is snug against our body and so is unlikely to snag, and secondly in case of an OOG emergency we can donate the regulator from our mouth using exactly the same well-practiced method we would when breathing the long hose. To do this from the right would require longer hoses. Just what we don't need; different stage reg hose lengths for each side.

Now for the shoulder d-rings: The d-rings have limited real-estate on them, lets see what a fully rigged DIR diver has on each one: LEFT: 2x stage cylinder bolt-snaps, 1 x backup light bolt-snap, total:3. Right: 1 x backup light bolt-snap, 1 x spare double-ended snap (for primary light), 1 x primary light bolt-snap, and finally the primary regulator is clipped off here when we aren't using it. So that's a total of up to 4 items clipped to the right shoulder d-ring - do we really have space for more?

Now add the scooter into the equation....