if you are properly weighted, how fast should you be descending? i am trying to avoid the overweighting problem, i am currently using about 10# and seem to drop quickly, when i use 8# i float about eye level with a breath of air, but seem to descend slower that the other divers i am with. also my breathing is long and deep, which is a normal way of breathing for me. any input will be greatly appreciated.
Question onproper weighting...
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Check your weighting at the end of the dive when you have about 500psi in your tank. If you can get down at this point then try taking off some removable weight until you can't do it and then put a pound or so back on.
Don Burke
Contributor
You should be descending at about 60 feet per minute.
The thing about floating at eye level on the surface is only rough guidance.
The real test of weighting is holding your shallowest stop, normally 15 feet, with your tanks at your minimum pressure, normally 500psig.
On descents, you may get a little more descent rate by exhaling at the surface and slowing the exhalation for the last half. Once you get a little momentum going, inhale.
It is normal for new divers to retain some air in their lungs at first and when they become more comfortable and fully exhale, they remove a few pounds of weight.
The people around you might be overweighted. A large portion of divers are.
The real test of weighting is holding your shallowest stop, normally 15 feet, with your tanks at your minimum pressure, normally 500psig.
i take this is with no air in your bc? sorry if the question is stupid sounding.
i take this is with no air in your bc? sorry if the question is stupid sounding.
Don Burke
Contributor
Absolutely correct.
That isn't a stupid question. In fact, I'd call it a good catch.
Thanks
Charlie99
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I prefer to be weighted so that I'm neutral or even negative at 15', empty BC, and full lungs. That's so that I can do a slow controlled rise from 15' to the surface. An alternative weighting checkpoint might be 6-8', near empty tank, empty BC, and lungs about 1/2 full.
It is best to do your weight check while horizontal in the water --- that way, even if you inadvertantly move your feet a bit, it doesn't affect your depth.
I'd ignore the effect of weighting on your descent rate at the beginning of the dive since there are too many other variables that affect it: how much air is trapped in your BC, has your wetsuit saturated with water yet, whether you have the 6 pounds of air of an 80 cu ft tank vs something bigger or smaller, etc. If you are horizontal, it is a simple matter to nose down and fin a bit if you want to descend faster.
If you are worrying about 8# vs 10# you are pretty darn close. What I find scary are all those divers wearing tons of weight because they try to descend with full lungs while unconsciously finning upwards.
It is best to do your weight check while horizontal in the water --- that way, even if you inadvertantly move your feet a bit, it doesn't affect your depth.
I'd ignore the effect of weighting on your descent rate at the beginning of the dive since there are too many other variables that affect it: how much air is trapped in your BC, has your wetsuit saturated with water yet, whether you have the 6 pounds of air of an 80 cu ft tank vs something bigger or smaller, etc. If you are horizontal, it is a simple matter to nose down and fin a bit if you want to descend faster.
If you are worrying about 8# vs 10# you are pretty darn close. What I find scary are all those divers wearing tons of weight because they try to descend with full lungs while unconsciously finning upwards.
We were always taught you are correctly weighted when you can hold a 6m stop with nearly no air in the BC with 50 bar in the tank.
In reality you want to be a tiny bit heavier than this - you may in some circumstances come up with less then 50 bar.
Also do the weight check without ditchable addons such as torches, cameras and so on.
In reality you want to be a tiny bit heavier than this - you may in some circumstances come up with less then 50 bar.
Also do the weight check without ditchable addons such as torches, cameras and so on.
This has been addressed often here but it's important.
You need to be neutral with a near empty tank AT THE SURFACE. For those who say neutral at 15 ft...when wearing a wet suit, it will expand and become more buoyant as you ascend right? If your neutral at 15 ft you'll be buoyant above that. Don't you want to be able to control your ascent all the way to the surface?
As to the original post and the question about descent speed...
With a full tank you be a few pound negative. However you should be able to descend as fast or as slow as you want. One of the bad things new divers seem to be tought is to let all the air out of the bc to descent and the result is an uncontrolled descent.
Let just enough air out so that you begin to descend as you exhale. As you descend and your suit and the air in the bc compresses you add more to compensate. The result is that you can descend as slow or as fast as you like and can stop at any time.
You need to be neutral with a near empty tank AT THE SURFACE. For those who say neutral at 15 ft...when wearing a wet suit, it will expand and become more buoyant as you ascend right? If your neutral at 15 ft you'll be buoyant above that. Don't you want to be able to control your ascent all the way to the surface?
As to the original post and the question about descent speed...
With a full tank you be a few pound negative. However you should be able to descend as fast or as slow as you want. One of the bad things new divers seem to be tought is to let all the air out of the bc to descent and the result is an uncontrolled descent.
Let just enough air out so that you begin to descend as you exhale. As you descend and your suit and the air in the bc compresses you add more to compensate. The result is that you can descend as slow or as fast as you like and can stop at any time.
True Mike, very true but with some new divers it's next to impossible to get them down.
Once they realise that they're not getting down because they:
1. are stiff as board 'cause they're nervous
2. inhale on descent instead of exhaling
3. dive rental gear, so buoyancy varies from one dive to another
4. move too much
which is round about dive #20, they can start taking weight off.
Now I've been known to spend more than an hour getting a student to descend while explaining he/she shouldn't (see above), but not every instructor has that kind of patience or time, so extra weight is put on.
Besides, I think that explaining to OW students about keeping some air in their BC's while descending, might confuse the issue. Neptune knows that buoyancy for some reason is a difficult subject for many students.
That said, I do teach the controlled descent in the PPB specialty. Now if only I could get people to understand that this isn't a waste of money, I'd be a happy man.
Sinkingly yours,
The Cat
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