What this is….an object’s mass (your body) within a medium (lake, pool, river, ocean) equals the weight of the displaced medium. Or as Wikipedia says: “An object that has neutral buoyancy will neither sink nor rise”. I drew a little picture that might help………..
What can I say …. I’m not an artist. But basically, if you’ve attained neutral buoyancy you can squiggle around under the water without fear of sinking like a rock or bobbing on the surface like a cork, thus my little friends Corky and Rocky (see above).
When a diver steps off a pier or the swim step of a boat they have some help from gravity in the initial descent. When you enter the water off the beach you don’t have that. My class entered off the beach.
Oddly, the Corky phenomenon doesn’t seem to have anything to do with one’s size, and apparently not even with the amount of weight carried around the middle. By that I mean I was wearing a belt that had actual lead weights attached to it….not easy to walk on land like that. Anyway….
After several weeks of pool training, our final test for certification took place on a grey, drizzly (I know, that’s a surprise) spring weekend in the Pacific Northwest’s beautiful Puget Sound. We walked in off the beach, in some cases staggered thanks to the weight belt, and swam to deep water. In a way it’s good to do it like that……….you have lots of time to get acclimated to your surroundings .. or.. drive yourself to insanity depending on personality type. I was dangerously close to the second option.
The problem with this method of water entry is after floating on top with an inflated vest or Buoyancy Control Device (BCD) you have to find a way to get under the surface of the water. This is still somewhat of a mystery to me. So while most were quietly, almost effortlessly submerging……….I was bobbing on top.
Each team of two student divers had a “dive master” to shepherd them thru the various skill sets. The “dive instructor” was the boss man. Teams went down in turns as the instructor ordered. My dive master submerged…my dive buddy submerged…then it was my turn. I let all the air out of my BCD, pointed my flippered feet straight down, arms at side, chin tucked, exhaled……and……I just kind of stayed there.
The various physical maneuvers I tried to make myself submerge defy description. You would have to see it to understand and even then you probably wouldn’t believe it. I was getting worried when my dive master popped up beside me. The instructor was in front of me. They decided to “assist” me.
Dive master submerges and grabs my foot. Instructor pushes down on my air tank. I’m flapping my arms pushing water upward trying to help. Presto…I’m under! If you’re at all paranoid this probably wouldn’t feel very good …….what with wearing lead weights and all..plus someone pushing your head under water. But I wanted my certification.
Once down under there was a particular skill test worrisome to me … mask clearing. The instructor completely removes your mask and hands it back to you. You put it on and clear the water out. You must be sure it’s securely sucked onto your face, no hair caught in the edge. To clear the water it’s like blowing your nose…cool, huh? That actually bothered me a little ….to blow my nose without a tissue. But you blow hard and the water swooshes out and you can see again. Well that’s the theory anyway. The instructor gave me high marks for persistence.
Through all of this Doug was somewhere on dry land snapping pictures. Mercifully, I think most of his pictures were lost when our computer crashed a couple of years ago, but I’m not totally sure and he’s not saying. I do know he was greatly entertained during the process.
Here we are after the last dive on the last day of certification. Success!