Hose Logic, Part III: Routing
As we saw in parts I and II, as GUE divers we use a long hose for our primary regulator and that regulator, the one we’re breathing, is the one donated in an out of gas situation. Part II highlighted some of the reasons for this:
It eliminates the possibility of donating a gas inappropriate for the current depth.
We ensure the diver in need of gas gets a functioning regulator. If your backup is fouled or otherwise not functioning properly, you are much better placed to deal with the situation than the already stressed, out of gas diver.
Formalising the procedure ensures consistency, whether breathing back gas, stages or decompression bottles, and with practice donation becomes a conditioned response—allowing pre-emptive action at the slightest hint of a problem.
Panicked divers will often attempt to grab the regulator in your mouth anyway. Accommodating this possibility avoids confusion and compounding the problem.
Using the long hose gives both divers room to move and manoeuvre, helping calm and control the situation.
It becomes easy to restow the long hose after deployment. Trying to restow a long hose that is bungied to a tank or otherwise not easily reachable or deployable, can be quite time consuming and challenging.
Consequently, the long hose is run from the right post:
The right post won’t roll off when impacting an overhead. At worst a significant impact will jam the post in the on position. If the long hose were running from the left post the opposite would be true. An impact would roll the post off, possibly jamming it in that position. Needless to say this stops the gas supply to the out of gas diver and could be fatal—the out of gas diver having no way to reopen the donating diver’s right post and the donating diver potentially being unaware of the problem—particularly while negotiating a restriction in single file (the original reason for the long hose).
Conversely, a left post roll off will be noticed immediately by the donating diver as their backup regulator would become difficult to breath or stop supplying gas altogether. If the post becomes jammed and the donating diver is unable to reopen it, they have access to a tertiary backup and can start breathing from their wing inflator by depressing both the inflate and dump buttons simultaneously. An option not available to an out of gas diver, no matter their routing.
While not as important as 1., this routing allows the long hose to run naturally from the first stage down the side of the tanks, across the front of the diver’s body, behind the neck and into the right side of the second stage, where most standard second stages feed from. Running the long hose from the left post would necessitate an abrupt change in direction, tight bend in the hose or a left feeding second stage to accomplish the same thing.
The LP inflator hose is also fed from the right post:
Running the LP inflator from the same post as the primary regulator gives immediate feedback if the gas flow to the inflator in interrupted—the diver’s primary regulator would also stop delivering gas. Placing the LP inflator on the opposite post to the primary regulator introduces the possibility of a gas delivery failure to the wing going unnoticed until needed—a potentially dangerous situation, considering emergency scenarios that may require immediate inflation.
In the event of a stuck inflator, disconnecting the LP inflator hose to prevent uncontrolled ascent is undeniably effective. However, it is not always possible, e.g. when a loss of intermediate pressure control in the first stage (high pressure seat failure) causes ice to form around the quick disconnect. If the LP inflator can’t be disconnected effectively, excess gas can be dumped from the wing with the left arm, using the rear dump valve (on the left of most wings), preventing a runaway ascent, while simultaneously shutting down the right post with the right arm. Running the inflator from the left post would make this impossible.
Feeding the LP inflator from the right post runs the hose behind the diver’s head. Gas flow through hoses, particularly when using helium, is audible at depth, and serves as another indicator of possible problems, e.g. leaks.
As mentioned, the LP inflator is a tertiary backup regulator. By feeding it from the right post we ensure that it is always available, never rolling off, and can be used by the donating diver if their backup fails or left post rolls off. Both divers can then still breath from the right post.
The backup regulator, hanging on a bungie necklace just below the chin, runs from the left post:
Splitting the responsibility between two first stages, ensures a redundant gas supply. The backup can be hung with the mouthpiece pointing up, allowing the diver to grab it without using their hands.
The SPG is fed from the left post:
The probability of a first stage failure is highest for the primary regulator—the stage with the greatest demand. Having the SPG on the left post ensures it remains relevant for the greatest length of time.
If the isolator happens to be closed, e.g. failing to run through the appropriate pre dive and pre filling checks, the indicated pressure won’t fall over time, giving the diver timely feedback that there is something amiss.
DPVs/scooters are typically operated with the right hand, leaving the left to manipulate the LP inflator, drysuit inflator, nose for equalisation, light head for signalling, reel, etc. Running the SPG from the left post gives the diver the same freedom to check it, without letting off the trigger.
GUE divers use a similar hose routing for single tank diving as well. However, for obvious reasons we run everything from a single first stage—with a standard right post style valve, i.e. no roll offs. While clearly losing some redundancy in a single tank setup, maintaining the same overall hose routing ensures consistent responses and equipment configuration for all of our diving.