Most recreational divers learn to share gas using a conventional octopus. You breathe from your primary regulator and carry a second, usually brightly colored, regulator secured to your BCD. If your buddy runs out of gas, you donate the alternate while continuing to breathe from your primary.
With primary donation, that arrangement is reversed. You give your buddy the regulator you've been breathing from and switch to your own backup, typically secured beneath your chin on a bungee necklace. Pair that arrangement with a longer hose, and the two divers have considerably more freedom to maneuver while sharing gas.
I use both configurations. When I'm working as a Divemaster alongside an instructor teaching conventional octopus donation, that's the system I use. Otherwise, I dive with a long hose. Having spent time with both, I have a definite preference, but I also understand why someone might choose differently.
The Conventional Octopus
The conventional octopus has an appealing simplicity. When your buddy needs gas, you locate your alternate regulator, release it from its holder, and present it to them. Your own regulator stays in your mouth, so you can continue breathing throughout the donation.
It's familiar to most recreational divers, works with commonly available rental equipment, and requires relatively little explanation when both divers have trained with the same system. Properly configured and maintained, it can serve recreational divers perfectly well.
What bothers me is how frequently the alternate regulator is neglected. I've seen octopuses dangling beneath divers, dragging through sediment, or tucked into places that would make them difficult to retrieve. A regulator intended to help someone in an emergency isn't particularly useful if nobody can find it.
Even when properly secured, the octopus is a regulator you haven't been breathing from during the dive. A thorough pre-dive check should establish that it works, but you're still donating a second stage that hasn't been in continuous use. That distinction matters to me, particularly when another diver urgently needs something to breathe from.
There's also the possibility that a frightened diver won't look for your alternate. They may reach directly for the regulator in your mouth, creating a situation that the conventional donation procedure doesn't necessarily anticipate.
Why I Prefer Primary Donation and a Long Hose
With primary donation, I give my buddy the regulator I've been breathing from and switch to the backup beneath my chin. The donated regulator was delivering gas moments earlier, and I know exactly where to find my own replacement.
This also accommodates the possibility of someone taking the regulator directly from my mouth. Rather than trying to redirect them to another second stage, I can transition to the backup I already know how to locate and use.
It's worth distinguishing primary donation from the long hose itself. Primary donation describes which regulator you give away, while the hose length determines how much freedom you have once you're sharing gas. The two are commonly paired, but they're not the same thing.
A conventional octopus hose generally requires divers to remain quite close together. That's manageable during a controlled training exercise, but maintaining buoyancy, communicating, and coordinating an ascent can become awkward when you're nearly face-to-face.
A five- or seven-foot hose allows more space between the divers while maintaining the shared gas supply. Each diver has room to manage buoyancy and body position without constantly pulling against the other person's regulator. I consider that a meaningful advantage even during ordinary recreational diving, where caves and overhead environments aren't involved.
The longer hose does introduce responsibilities. It needs to be routed correctly, secured without interfering with deployment, and kept clear of equipment that could trap it. If I cannot donate the regulator and deploy the hose smoothly, the additional length isn't helping anyone.
Those skills need practice, particularly when switching configurations. A hose that looks perfectly arranged while standing on a boat may behave differently when you're horizontal, wearing exposure protection, and trying to help another diver.
Suddenly, Your Backup Regulator Matters
One of the more amusing consequences of switching to primary donation is how your attitude toward the backup regulator changes. With a conventional octopus, it's easy to think of the alternate as equipment intended for someone else's emergency. You might test it before diving and occasionally breathe from it during training, but otherwise it spends its life secured to your BCD.
With primary donation, you're the person who will be breathing from that backup when your buddy needs gas. Suddenly, its breathing performance, maintenance, and accessibility feel considerably more personal.
I find that this changes how I think about purchasing and maintaining regulators. I'm much less interested in a cheap secondary second stage simply because someone has designated it the backup.
Both regulators need to be dependable regardless of configuration. Primary donation just has an effective way of reminding you why.
Being the Odd Diver on the Boat
On most recreational dive boats, I'm the only person using a long hose. My assigned buddy may never have encountered that configuration, and there's no reason to assume they'll understand how it works.
Before entering the water, I explain which regulator I'll donate and show them how the hose deploys. I also identify the backup beneath my chin so they understand what happens after I give them my primary. If the arrangement is unfamiliar, demonstrating it is considerably more useful than simply announcing that I use primary donation.
This fits naturally into the approach I describe in My Insta-Buddy Pre-Dive Check. I'm not trying to conduct an equipment seminar on the boat. I want both of us to understand how we'll share gas if something goes wrong.
The conversation needs to work in both directions. If my buddy uses a conventional octopus, I want to know where it's secured, how it's released, and what they expect me to do when I need gas.
A configuration that's familiar to me may be entirely unfamiliar to someone else. Our equipment doesn't become safer merely because we're individually comfortable using it.
Which Should You Use?
I prefer primary donation with a long hose because I like knowing that the donated regulator was just working, having my own backup immediately accessible, and giving both divers more room during a shared-gas ascent. That doesn't mean everyone should switch. A conventional octopus that's properly maintained, accessible, and used by someone who has practiced donating it is a perfectly reasonable recreational configuration.
What I wouldn't recommend is changing equipment simply because another diver insists their arrangement is superior. Whatever configuration you use, understand its limitations and practice with it. A regulator exchange performed while kneeling on the bottom doesn't tell you everything about managing two divers who need to remain together while swimming and ascending. The actual emergency, including the responsibilities of both divers, is covered in Sharing Gas: What Both Divers Need to Do.
For my diving, the long hose remains my preference. When circumstances call for a conventional octopus, I'm comfortable using that instead. Knowing how both systems work makes me a more useful buddy than insisting that everyone adopt my preferred equipment.