Weighting Paradox

[Goingforsound]

I started in shorty salt water at 12pounds for a 225# guy 5'10" in a rec bcd.

Within 10 dives went to 10, 5 other tropical dives went to 8. Its pretty ok. I just bought a wing with a SS plate and expect to require no additionnal weight with a full 3mm.

 

[Doby45]

I would also say that if you are sinking at your stop with nothing in your BC then you are not fully dumping your BC on initial descent. If you simply hold your inflator up and dump air it should properly squeeze any hidden air out of your wing. If you are going head first then I agree with @nolatom that stated you are more then likely not using your rear dump or you have air trapped on the side that does not have a dump.

 

[BRT]

Don't forget to exhale on initial descent.

 

[Bob DBF]

I would also say that if you are sinking at your stop with nothing in your BC then you are not fully dumping your BC on initial descent. If you simply hold your inflator up and dump air it should properly squeeze any hidden air out of your wing.

I found that there was over 5# positive buoyancy in my old jacket, after the bladder was fully deflated, from the padding of the unit. It would decrease some after a trip to depth, but was always back when the BC was dry. This is enough to give the OP problems. I was always a swimmer/snorkeler, and started duck diving before SCUBA, and kept up the practice after, so I never had an issue. As a matter of fact, duck diving was taught as the method to submerge on SCUBA in the early '60's.



Bob

 

[Goingforsound]

I believe duck diving is still shown in the padi OW book.

 

[Patoux01]

How much gas do you have at the safety stop? The key thing is to remember that if you are at that stop with 20 bar in an Alu tank you will have different buoyancy to 60 bar in a steel.

Yes the buoyancy of tank will be different, that of the diver as a whole will be pretty close... High off it'll be 0.5kg off.



The easy way to descent? Dive twins

Even without that, descent is not THAT difficult once you understood how to "fully" empty your lungs, and namely that you have to keep it there for a "long" time before you'll really start going down. (Much the same underwater when controlling depth with your lungs).

Being slightly, and by this I mean like 2, maybe 3 pounds, is not a big deal, it shouldn't be dangerous. If you sink like a rock on empty BCD with an almost empty tank, then you're way too heavy.

 

[boulderjohn]

I believe duck diving is still shown in the padi OW book.

No, it isn't--just the opposite. Students are taught a feet first descent.

I have been a PADI professional for 12 years, and it was never included during that time. I was PADI certified long before that, and it was not taught then.

 

[dumpsterDiver]

Hi all.

Hopefully some of you can help out with a bit of a weighting paradox I have:

I'm constantly on the lookout for tips and advice on being a better diver and I came across this article recently: How to Reduce Weight When You Dive • Scuba Diver Life All good and well, nothing really new or revelatory in there.

Generally, I consider my weighting to be good (4kg). On most dives I only need to add a little air in my BC once I'm near the bottom and I'm happy as Larry.

But, with my current setup, if I empty my BC at the safety stop, I sink. Conventional wisdom says that means I'm over weighted. However! When I start my dive I always have to work a little to get down the first few meters. I flap like an injured seagull on the surface when I'm trying to descend. Once I'm down to about 3m, I then sink just fine.

My descent strategy is to empty BC, tuck my knees to my chest, exhale and roll forward. I end up with my fins out the water and require some ungraceful kicking and flapping to start my descent.
So, am I underweighted, overweighted or just descending with bad technique? I realise this is one of those things that's impossible to diagnose in a forum, but any tips or comments?

Thanks.

The answer is simple.. dive like a real diver and move away from the silly way you were taught in scuba class. Do a proper surface dive, or duck dive, which lifts your legs out of the water, this should provide enough weight to assist in your descent, exhale,kick hard and equalize until you are 15 ft down. If you can learn to do a proper duck dive, you will not be so ungraceful at the surface. The solution is not to wear more lead, but to learn to do a better surface dive. If you are diligent about sucking all the air from your BC after a dive, then you should be able to sink feet first with a full tank. But it is a slow process and delays your descent.

Many times I forget to vent enough air from the BC and I have to splash and kick at the surface. I never use a butt dump, so I either have to power down or conceed defeat and spin around and dump air. Also it is fine to be a little heavy at the stop so you can pull down on the string of an smb.

 

[sunnyboy]

I rank the priorities as follows: Most important - holding a 20ft stop with 'near empty' tank. I actually want to be able to stay on the bottom in any depth less than 10 ft. but holding a 20ft stop without needing to grab rocks is pretty much mandatory in my books.

Second is trim. You should be able to hold a horizontal position without pivoting in an uncontrolled manner (i.e. tilting to the right or left, or tilting head down etc.). If you can hold horizontal without effort then you should be able to position yourself in any orientation. I consider this extremely important if you wish to take good photos.

Third is submerging. On the surface, you should be able to RELAX, exhale and sink at a pace that does not rocket to the bottom, but does descend nicely. From surface to 10 ft, if you watch your depth gauge I like to see it drop about 1 ft per second or two (that's 30-60ft /min).

You should be able to get deeper than 4ft before you need to inhale, and don't fill your lungs - just breath easy on that first breath so you continue to descend.

<EDIT> Once I am at about 4 ft down (sometimes less), I do rotate from feet first to horizontal and continue the descent in a horizontal orientation so I can look about easily. </EDIT>

The only time I had to "duck dive" was very early on when I was borderline underweighted and very inexperienced. It takes time to learn to relax and 'let it happen' on descents.

As to diving like a "real diver", and not like you are taught in OW class, what utter B.S. Even the "GUI dive gods" teach feet first descent. If they still do it, it must be the right way. ;-)

 

[archer1960]

I rank the priorities as follows: Most important - holding a 20ft stop with 'near empty' tank. I actually want to be able to stay on the bottom in any depth less than 10 ft. but holding a 20ft stop without needing to grab rocks is pretty much mandatory in my books.

Second is trim. You should be able to hold a horizontal position without pivoting in an uncontrolled manner (i.e. tilting to the right or left, or tilting head down etc.). If you can hold horizontal without effort then you should be able to position yourself in any orientation. I consider this extremely important if you wish to take good photos.

Third is submerging. On the surface, you should be able to RELAX, exhale and sink at a pace that does not rocket to the bottom, but does descend nicely. From surface to 10 ft, if you watch your depth gauge I like to see it drop about 1 ft per second or two (that's 30-60ft /min).

You should be able to get deeper than 4ft before you need to inhale, and don't fill your lungs - just breath easy on that first breath so you continue to descend.

<EDIT> Once I am at about 4 ft down (sometimes less), I do rotate from feet first to horizontal and continue the descent in a horizontal orientation so I can look about easily. </EDIT>

The only time I had to "duck dive" was very early on when I was borderline underweighted and very inexperienced. It takes time to learn to relax and 'let it happen' on descents.

As to diving like a "real diver", and not like you are taught in OW class, what utter B.S. Even the "GUI dive gods" teach feet first descent. If they still do it, it must be the right way. ;-)

Nice summary, but I would disagree with you on one relatively minor point: Just because your weighting allows you to hang horizontally, does not mean you can hang head up or head down as needed. That takes some additional tweaking of your weight distribution to be able to hang in whatever attitude you need at the time. I have spent a LOT of time messing with this...