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Sinking Like A Stone...

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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New Member
Jul 19, 2004
Hey Guys,
I have found that I sink like a stone. Even on full inhale with 3-4 packs I sink after only 3-4m of water(fresh).

What is the average buoyancy for you guys? What should I do about weighting myself for positive buoyancy?

Any other thoughts or comments on the concept of human buoyancy would be appreciated. Thanks,

I used to dive with someone who was just the same. He was (as I remember) slightly negative at the surface, with a 6mm wetsuit and scuba gear in salt water. This was so bad, that in the pool sessions he could almost be classed as a non swimmer.
With how much weight is that? If none, then you could add some "buoyancy packs" if you need. :)

If you are spearing in 6-8m of water, then you are weighted correctly, it all depends on how deep you are going and what kind of activity you are doing.
Many people prefer different ratios of negative/positive.

For fun diving at 20m+ (I dove only in saltwater so far) I like to be neutral at 12m-15m. If I would be going to 12m-15m I'de add another kg of lead.
Last time I tried spearing at 5m-8m I added yet another KG and was still too buoyant at the bottom (and it was like a desert there :waterwork).
I'm similarly buoyant to you, and I believe a few other freedivers I met are as well. In fresh water, I am slightly negative at the surface with anything less than a full breath, and with packs, I am negative around 2.5-3 meters. This is without a wetsuit, of course; are you that negative with a wetsuit on?

Personally, I'm happy being negative shallow, as long as the seas aren't too high. This is especially true for free immersion, where I found an extra two lbs. of ballast really helps. I'm still positive at the surface, but I'm neutral by 10m in a 4mm wetsuit. The climb up from depth is a little more work, but it hardly hurts the performance. And the trip down is almost effortless; really relaxing.

If you really want more buoyancy, extra packing will obviously do it, and is certainly the best way to go about adjusting your buoyancy at "runtime", as long as it's comfortable for you. Beyond that, why not get a sheet of 2mm neoprene and stick it in the back of your wetsuit?

The only long-term method for increasing buoyancy that comes to mind would be to somehow put on some fat :)

But hey, I recommend you learn to love that sinking feeling. After all, going down is the fun part; returning to the surface is only a necessary evil :)

interesting. i posted a thread a while ago about that:

i find that most amazing. i´d be really interested if anyone has some explanations for these differences. supposedly the body itself is pretty much neutral and there are obviously variations. but a difference of 10-15m in neutral buoyancy without suit and weights must have some explanations.

No, I am actually that negative without wet suit or anything. I actually have never needed to use a wet suit. I agree, it is cool to be able just to sink straight out, but kind of annoying when trying to get a good breathe up. Also, I do not want to have SWB and then sink right back into the abyss without weights. That is my main concern.

Deepthought mentioned "bouyancy packs", what are they? Is there a preferred way to make or buy them?

Thanks for the input guy's. But I am still curious, what causes such a huge difference in bouyancy between people?

I met a guy this summer who would sink even with a wetsuit on. He was a really experienced scuba diver.

He claimed that he'd been able to float just like anyone before, but just changed sort of "over night" (well, according to him, over a 2 weeks drinking spree :).

The best that any doctor had been able to explain it to him, was something vague about bones filling with fluid for some reason. I don't know if that's a valid explanation or not, but I did witness this guy doing his dives with a (I guess, maybe 5mm) 7mm wetsuit and no weights, and still having trouble keeping afloat.
Buyancy packs.

I don't remember where I saw them or heard about them, but it was some kind of incompressible plastic capsuls (I think) that you connect to your belt.
Shouldn't be too hard to find some possitively buoyant stuff to connect to your belt, no?

Adding fat and neopren is also an option.
Thanks for the replies guys,

I may have to get my hands on some "bouyancy packs", this sinking thing is beginning to be a bother, and I am not about to gain some weight.

Does anybody have any thoughts on that guy sinking "overnight"? Your bones filling with liquid seems pretty unlikely to me.

So, how am I supposed to be weighted if I am doing recreational dives to about 15-20m? Do I need to add some buoyancy?

Damn, sounds almost like me. In a 2mm shorty in a pool on a half-lung I sink; I can only float with a full lung, and marginal at best. I classify myself a non-swimmer because the effort required to keep my swimsuit-clad body at the surface, completely overshadows my forward motion and I tire far sooner than I should.

I started out playing underwater hockey wearing the shorty although I've now ditched it at my teammates' pleadings. I had been worried about staying at the surface long enough to breathe.....

In a full 7mm wetsuit I believe I need only about 2 or 4lbs, though in shallower water I wear 6 for good measure.

oh yeah FWIW I'm 5'2" and 114lbs.
Well, seems like there are a few of us out there. I have no need for a weight belt in a 3mm suit, even in the med. It's true that it is a bonus on the journey down, but treading water can become a pain! All this is even worse in a pool and no suit... People even comment on how negatively bouyant I am

I too am curious as to why this is. Not sure about bones filling with fluid? But in favour of the idea that ones bouyancy can chandge, I swam for the school (many moons ago) and crawl was my first choice of stroke. Now, crawl demands so much attention from my legs (which sink readily) I go for breaststroke. Maybe I've lost the stroke, but there was definitely a change (no over two weks though).

Interesting subject...
Buoyancy belts

There are foam belts that are used for in-water exercise that should be nearly ideal.

The cells are dense foam that are a little larger than regular diving belt weights. Think of a boogie board sliced up into square chunks, with a hole through each chunk to accomodate a belt.

I'll see if I can get the manufacturer's name and/or post a picture later tonight.
when deepthought wrote about buoyancy packs, i thought he meant packing more air. i read all this with great interest and the number of people who are seemingly very negative seems bigger than i would have guessed. i assume, though, that everyone is diving on a maximum inhale, no? which makes this all the stranger.

the only buoyancy belt i´ve ever seen is a thing that little kids sometimes wear. bright yellow. seems like a rather ridiculos idea to go freediving with such a thing. anyhow...

i´d rather be wearing adjusting buoyancy with extra neoprene than with a belt. plus it keeps me warm.


...or get rid of your heavy thoughts
It's true that it is a bonus on the journey down, but treading water can become a pain! All this is even worse in a pool and no suit...

Slippery eel, you should really wear a suit in the pool. I don't know about where you live, but here public nudity is not smiled upon. :D

It's interesting to see how many people here are this negatively bouyant. I figured I was one of very few, but I guess it is more common than we all thought.

Has anybody figured out what causes this yet?

Sounds like a "bouyancy pack" or belt would just be to ridiculous to wear first of all. Secondly, it doesn't sound very efficient for the low gear freediver. Sounds like more neoprene is the more efficient option. Maybe I just need to work on my lung volume?


Thanks for a good thread, I learned some interesting stuff.

To your question, Three things affect density of the body: lung size, relative amount and density of bone, and fat content of the body. Bone density is one thing that isn't readily apparent and can make a big difference.

If you want to make yourself more positive and add some to your dive time, consider a longterm regime of stretching and packing to raise overall inhale volume. Add diaphram stretches to reduce residual volume and you get a double benefit, helps a lot clearing at depth. Everbodys different, but I would think you could get a +1 kg, or close, out of it.

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