Looks cool and might keep you under any airline weight limits? Not a big advantage IMHO, but marketing is strong in this industry.
Noob questions about various weight(s) topics .....
- Thread starter xanaphyst
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For a breathing cycle of 1 liter, you can breath in the range of 0-1L at the end of the dive and perhaps a range of 3.5-4.5L at the beginning if your lungs are large. The difference in average of 3.5L compensates for about 8 lbs of negative buoyancy due to gas and/or suit compression. Certainly this is easier if diving in warm water or smaller tanks.
The danger for the unskilled is CO2 retention and the associated headaches and higher susceptibility to narcosis. While it can be done (and everybody had to do it that way before the BC was invented), it's relatively rare these days.
Congrats on the certification! The items above are good.
1.) You don't want manage a lot of air in your BC. It expands when you go up, suddenly giving you more buoyancy than you want, and then is compressed as you descend, causing you to sink faster than desirable. It's task loading. AVOID task loading until you are more experienced.
2.) When things REALLY go sideways, take your weight belt off and swim the F up while blowing some bubbles. Maybe that's not taught anymore. That's why beginners should stay shallow. It's easier to survive.
Shallow means much higher odds of not getting bent when going up and being able to make it to the surface. People like to talk about "techniques" and "procedures" (obviously, it's a diving class) but if you've been around diving long enough (43 years for me) you know that bad situations usually include a lot of confusion, lost buddy, hard time communicating since you are underwater; things people don't anticipate, things you weren't taught, etc, etc, etc. Go the F up. Don't be embarrassed. Don't worry about the bends on a 30-60' dive. Don't worry about your kid; they're total pros after dive 1. Mom and dad are rubbish. The kids will be watching you with a confused look on their faces. Again, don't be embarrassed. If it's a real emergency, don't F around. Ultimately you are responsible for you even as a beginning diver. Just keep your airway open as you go up. Live to dive another day.
3.) No idea
Here's what you should do. It's fundamental.
(And if a dive operator doesn't let you do it when there is no current and it's a slow day, shame on them).
- After a dive, gear up with a 500-1000psi tank; more towards 500 is better. It will be more buoyant, helping you target the right amount of weight at the end of the dive or if you run low on air. Your gear will also be wet with the air bubbles out of it; more like a dive.
- Take no weight other than a weight belt with 2 or 3 pounds it (just one weight). Get into the water fully geared with the reg in your mouth.
- Take the weight belt off and hold onto the loose end (it's embarrassing if the weight slides off and you lose it). Push the weight over to the buckle side so you have room for more weights. Let the weight belt dangle in front of you.
- STOP KICKING you're a diver with the reg in your mouth. Deflate your BC. Breathe IN all the way and OUT all the way REALLY slow. You probably won't sink.
- Once again, STOP KICKING. Have someone pass you a 2/3 pound weight. Breathe in and out again (slowly).
- Continue adding weights like this (and stopping kicking!) until you sink when you exhale. That's your neutral buoyancy. Hand the weight belt up. Add 2-4 pounds and plan your next dive. You'll find that you're not a yo-yo, crashing into reefs and futsing with your BC or having to swim upwards constantly during the dive. You should be able to rise a bit on a nice big inhalation and sink on an exhalation. That's a good start.
I've got 860+ dives and at least 800 of those have been with no ditchable weights. Some of us believe in diving a balanced rig and managing the risks that could require ditching weights in a different way. There are also very real risks that come from ditchable weights, namely losing them inadvertently. I hold to the belief that this is far more common than the scenario that would in fact require the ditching of ballast.
It won't kill you, but extra weight means unnecessary gas in your BCD which makes it more difficult to stay at a new depth without kicking, adding or venting gas from your BCD, or messing with your breathing. A larger gas bubble also increases your drag slightly. All of this result in increased gas consumption and a less relaxed dive.
@inquis gave a great answer here. I'll just note that if you are not overweighted and on a typical warm water dive with an AL80 or even an HP100 and no more than a 3mm suit, there is no good reason to drop weights underwater. A few of the OW training skills, or at least how much they are emphasized, are leftovers from the earliest days of scuba training which was before the BCD and SPG were invented. There are a lot of scenarios under which you would want to ditch weights in those days that do not apply to most modern diving.
Many of us here dive with a steel backplate and wing instead of a fabric and plastic BCD. The weight of the backplate, along with avoiding the positive buoyancy of the typical BCD, provides a large part of the ballast we need. For example, with my rig and little or no neoprene, I only use 3-4 pounds of lead with an AL80 and none with an HP100. It's a real delight diving without all the bulk and weight of a traditional rig. If travel weight is an issue, you can substitute a lighter backplate (aluminum, skeletonized steel, carbon fiber) and attach trim pockets which will allow you to add most or all of your needed lead once you arrive at your destination.
It only matters if you are flying with it and trying to meet weight limits. Other than that, the extra weight just means you get to drop off neary that amount in lead. Brass (and stainless steel) are about 8x as dense as water, versus around 11x for lead.
However, it doesn't necessarily mean it's less durable. Some first stages are lighter because the body is made of titanium which is stronger and more corrosion resistant than brass. And some others are durable, but stripped down, designs. You don't actually need environmental sealing or swiveling turrets or big heat sinks if you are doing single tank temperate or warm open water dives.
gmerick
Contributor
No, there is only about 2.5-3kg of air in an AL80. It's very easy to breathe off the top of my lungs at the beginning of the dive, and by the safety stop be breathing off the bottom. It's only a 3l change in lung volume.
That is why a little extra weight is not a bad thing: 2 pounds over "ideal ballast for a perfectly spherical diver of uniform density" will not make a noticeable difference at the start of the dive, but they may at the end.
johndiver999
Contributor
And is that a good thing? Is that an optimal way to decompress? Does this technique allow you to deploy an smb from depth and then keep it erect?
This sounds like a silly game to play. One that might be useful, because you screwed up or lost lead during a dive, but certainly not something to be emulated or planned for, right?
OP
xanaphyst
Registered
Thanks everyone for all the answers. It definitely cleared up a few things. I think I'll carry forward with the following plan:
1. Wetsuit should be 3 mil or less
2. Get some real fins instead of my little shorty travel fins
3. Establish my neutral point with an AL80 at 500psi using permanent weights
4. Add 2 to 4 lbs as drop weight
As I understand it this will put me good enough at safety stop, the ability to kick to surface if needed, and the option to adjust weight as needed in the weight pockets until I determine my final weight plan.
1. Wetsuit should be 3 mil or less
2. Get some real fins instead of my little shorty travel fins
3. Establish my neutral point with an AL80 at 500psi using permanent weights
4. Add 2 to 4 lbs as drop weight
As I understand it this will put me good enough at safety stop, the ability to kick to surface if needed, and the option to adjust weight as needed in the weight pockets until I determine my final weight plan.
Watterlogged
Banned
Ive been diving since 2004 and i look forward to reading the answers as i have ALWAYS only dove for fun. to be under the water with stuff. Without doubt im about to learn alot.
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