Dive Gear: Alternate Air Sources
As a new or regular diver you hope that you will never need a back up air source. However, if your buddy or any other diver approaches you and signals out of air, or even your own second stage not functioning, you will be able to take action. This is because you, as I do, will always be diving with an alternate air source.
If you are currently using a school set and thinking about your own you will need to decide which type of alternate air source do you need.
Choosing an Alternate Air Source
At Scuba Leeds we teach in a wing with a long hose configuration. Your choice will be different for this to a regular short hose jacket set up so let’s see if I can help.
Long Hose Configuration
On a long hose your alternate air supply is worn around your neck and you donate your primary. So as to aid identification the alternate is often coloured yellow in a long hose set up. This is because you do not want someone grabbing a yellow regulator if it is around your neck. They will not get far and if the elastic is tight it is likely to smack you in the face!
On all of my set ups I have the same regulator as my primary and alternate. On my single I have (Apex MTX-R) so I use the yellow version as my primary. For my twin and side mount set up I have black regulators (Apex XTX 50’s) on both. You can get a yellow version but as I use these for sidemount, there are times when I may be using either. During the buddy check I am always clear that in an “out of air” situation, I will donate to you. This is simply because I know which one I am using.
What is Right for Me?
So before you head in to the shop to place your order you will have to decide what set up do you want? Talk to people, listen to what they say, assess this and weigh up what sort of diving you will be doing in a year or two time as this should direct you. It is easy to get it wrong and we will all have our preferred set ups… but do they suit you?
There are also different options for alternate air sources. You can have an octopus – this is what an alternate air source is referred to as. As said above these can come colour coded. Often these are cheaper models when sold as a set. In all reality they are just a regulator that you are using as an alternate air source.
You can get Scubapro Air 2 which connects to you low pressure inflator. This is designed to be a second alternate air source really but it would work. I would not recommend this as your only alternate air source as this is very different in an emergency situation.
It is possible that you have heard people talk about redundancy. Your alternate air source could be from a redundant system, this is usually from a pony system. This means having two first stages so will increase the cost. In simple terms you have two first stages each attached to a separate air source. Your pony bottle is often attached to your main cylinder. To decide the size of the pony you should apply the rules of third and this should be the minimum size of you pony. There are also product that look likes a aerosol with a mouth piece (Google Spare Air). These are not really alternate air sources and if this is all you have… I am not diving with you.
Alternate Air Etiquette
• Always during the buddy check breath from both second stages at the same time – this what you will do in an out of air situation so make sure the first stage can cope with this demand. In an air share at depth it is better to breathe in as you sharing buddy breathes out.
• Do not let the octo dangle, keep it in tight – it should not damage the environment and it keeps you streamlined and no one likes a mouthful of sand.
• Do not let it leak or free flow – set it to pre dive if possible and keep it turned down.
• If it is needed offer the octo the correct way up – no one likes a wet breathe.
• Stow it in the triangle from you chin to your hips preferably on the right side – keep it seen and easy to access.
• The alternate should be on a hose long enough to make donating easy. This is not an issue with the long hose set up when donating the primary regulator.
A buddy check is important as this enables you to know your buddy’s gear and they to know yours. You should always know your buddy’s equipment before you dive.
Scuba Leeds Training
As explained above with a long hose set up I prefer to donate my primary regulator in an emergency situation this helps my buddy as I am giving him a regulator he know is working as he can see it is working.
The opposition you may hear to this practice included concerns that both divers will be without an air source for a time period. Different training may cause confusion to novice divers. We have amended our training when using long hoses so that all new dives are trained to donate the primary in an out of air situation.
End the Dive!
In any situation where you have needed to use an alternate air source this is an indicator to end the dive. In most situations you will make directly to the surface, however, in a confined space the long hose allows you to exit in a line with the receiver at the front and the donor behind… this may not be possible on a regular octopus set up.