Yes, you read that right. This blog post is going to talk about rehydration and eating underwater. During the dive. Can that be done? Read on and find out.
As (budding) technical divers we all know that hydration before and after dives as well as during diving days is important. But what about the time on the dive? Granted, even longer open circuit dives are usually short enough to manage with eating and drinking before and after the dive. CCR rebreather diving, however, can mean much longer dives, often resulting in several hours underwater. This means in-water rehydration becomes a realistic consideration.
Now, it wasn’t my idea. In fact, I was introduced to eating and drinking underwater by Marc Crane during Advanced Mixed Gas / Mod3 CCR course. Only recently have I gone back to the concept when the plan was to complete a very long dive to try and connect two dive sites along the same reef.
However, the idea of ‘refuelling’ during an activity is not new. Long distance runners regularly do this, and there are specific energy gels available that are eary to carry and ‘eat’ without stopping. Even on shorter runs or whilst jogging, many people will carry water or electrolyte drinks to quite literally rehydrate on the go. In fact, I used to do that when I ran regularly. Feels like a lifetime ago…
How to eat and drink underwater
But back to diving. How do we eat and drink underwater? Drinking is quite straightforward. If you take a closer look at the picture at the top of this blog (thanks to Thomas Ozanne / arewedreaming.com), you can see a blue hose sticking out next to my loop on the right. (Apologies for the imperfect mounting / configuration of the system, but it was a trial.) That hose is connected to a camelbak filled with water, and its outlet is secured close to the bottom of my exhale counterlung. You can just spot it below the loop. Drinking proved easy: close the loop as if you want to bail out, find the camelbak hose, take a sip and then go back on the loop.
Eating was a bit more difficult. First things first – I wouldn’t recommend coming off the loop, eating anything ‘substantial’ and going back on the loop. That would result in something very messy. The energy gels runners use would work well, because there is no chewing involved. In this case, they weren’t available.
What’s the next best thing? Chocolate! Who doesn’t like a bit of salted caramel? The idea, both on the Mod3 course and on this recent long dive, was to wait until the late stages of the dive when we are decompressing in 6 m or shallower. At this point the diver has performed an oxygen flush. Breathing a PO2 of 1.6 is essentially the same as breathing open circuit oxygen. So, as you can see in the pictures, I switched to open circuit and enjoyed my chocolate bar. The secret is to take small bites between breaths and to clean your regulator very well afterwards.
Did it make a difference? Perhaps. I believe being able to rehydrate by sipping water every so often meant that I generally felt better after the dive. With a few tweaks, it would also be quite simple to bring the camelbak along regularly. As far as eating goes, I don’t believe these dives were long enough to make a big difference. However, exiting the water with a rebreather and multiple stages requires energy. This is true for boat or shore exits. Having something to give you that little boost just before the exit was nice.