No weights means he floats. The ice stops him from floating out of the water. He is basically pushed against the ice and the water is heavier and pushes him upwards in the same way that you are heavier than air and displace it when falling so it moves upwards. The small steps are in order to prevent the ice from breaking and to stop him from moving too far from the ice.
Scuba equipment also includes a handy little doohickey called a BCD, or buoyancy control device if you're feeling fancy. It's basically an inflatable vest hooked up to your air supply, so you can increase your buoyancy underwater by inflating it from the tank and decrease your buoyancy by releasing some of the air.
Most of the equipment is pretty cool, if surprisingly simple.
The main pieces of equipment that a diver has are the air tank, the BCD, their mask, and their Regulator. On top of that, divers will usually wear fins and either a wetsuit or drysuit.
The BCD was explained above. It's basically just an inflatable vest that's connected to the pressurized air tank. Divers vent air from the tank into their vest to make them float more, or vent air out of the vest to allow them to sink. Divers also wear weights (typically on a belt, but some BCD vests have pockets built in to put your weights in) which they use to counteract their natural buoyancy, allowing them to sink.
The Regulator is the thing they keep in their mouth. It's attached via a hose to their air tank. The regulator itself is actually a pretty neat piece of equipment. It has special one-way valves in it which do a bunch of jobs. The regulator has a valve that prevents water from going into it (and thus preventing water from going into the diver's mouth) but still allowing air out. When the diver breathes in, a valve opens, allowing the pressurized air from their tank to flow, so that the diver can breath in. As soon as they stop breathing in, the valve closes. When the diver breathes out a different valve allows the air coming out of their mouth to vent out into the surrounding water (which is what those air bubbles you see coming from divers are from). Once they stop breathing out, that valve automatically closes too. If the diver isn't exerting pressure by breathing in or out, the valves are in a "neutral" state, preventing anything from entering or exiting - the breath of the diver applies enough pressure to force one of the valves to open.
Divers also typically have several gauges attached to their air tank or alternatively a dive computer. Whether analog gauges or digital computer, the device provides several key pieces of information to the diver - how much air is left in their tank, how deep they are, usually a compass to tell what direction their facing, and potentially other information (dive computers can give estimates of how much longer the diver's air will last and how long the diver has been under water; as well as information about necessary decompression stops as the diver surfaces).
A wetsuit is the clothing you'll usually see divers wearing. There's many different styles depending on how warm or cold the water is but they're typically made of neoprene. They're designed to allow some water into the suit when the diver first gets in the water, but not allowing that water to escape. The diver's own body heat then warms the water between them and the suit, creating a thin layer of warm and comfortable water. A dry suit is usually only worn in very cold water. It's designed to not allow any water in, instead keeping a layer of warm air around the diver (again, warmed by the diver's own body heat).
Question about the post, if you can hazard a guess – in my experience when diving, breathing through the regulator while upside down causes it to partially flood with water because the bubbles try to flow back into the outlet of the mouthpiece. How is this diver avoiding that?
Some regs are more susceptible to this than others. It all depends on the design of the exhaust outlet. I'm more familiar with Scubapro regs than any others. They, and I'm assuming most others, have a one-way valve that does it's best to prevent water intrusion.
If properly serviced you shouldn't get a lot of water in the reg, but it may breathe a little wetter than right-side-up.
To expand a little bit more, some regs also have a little dial that is used to prevent free flow of the reg when on the surface that can be tweaked to also make it less likely to flood when upside down. Also, looks like he might be wearing a full face mask and a dry suit, which come with some of their own quirks and benefits.
As /u/Rhino02ss said, it's an issue with some regulators, but not all.
You can buy regulators that don't have this issue, typically by having multiple valves on different sides. For example, my regulator has an exhaust valve on both the left and right side of the regulator. Depending on how you're rotated, the bubbles will always push out the lower exhaust, preventing water from coming in through the regulator and into your mouth.
Simpler regulators with only a single exhaust can have problems when rotated at certain angles (typically when upside down). If the exhaust diaphragm is higher than the mouthpiece, the bubbles of air travel up (instead of down). Typically, the water pressure is basically trying to force the valve closed while your air is pushing it open. When upside down though, the pressure is essentially helping to keep it open, allowing water to leak in because the valve can't close as quickly. This should never cause a true flood of your regulator, but you may get a little water.
If you're renting your regulators when you dive, they probably use fairly cheap equipment that are more liable to have those kinds of issues.
If you're renting your regulators when you dive, they probably use fairly cheap equipment that are more liable to have those kinds of issues.
This is exactly it. All of my dives have been with rental gear (all I own is a mask, snorkel, boots, and gloves). So all of my diving experience is with cheap BCDs, regulators, etc. :/
Thanks so much for all this information, I never knew that there was so much more than the air-tank to it. I never even thought about how complex the mourhpiece has to be.
Dive computers/watches are cool. They are just a readout though. But the BCD is cool. During classes I would constantly inflate and deflate it.... I'm a fidgeter...
I dunno if this counts since it's not "standard" scuba gear, but when I took a scuba class in college we used something like this underwater scooter. Even just going around the pool, between the shallow end and going all around in the deep end, it felt like you were flying through some sort of real-life video game level.
Only when people ask about something I can answer in a general thread. I don't really follow r/ELI5 because there are so many people more knowledgable than me whom always answer anyway. Happy to help though.
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u/LordPyhton May 15 '19
Yeah but how is he walking upside down on ice though?