Buoyancy Challenges

[azapa]

Hi All,

I have been diving solidly for 18 months now, and dive in the ocean at least 30 to 50 times per year, lucky me!

I am a very freediving oriented and have completed a Level II FIT course in Miami. I have a 4:40 static, and have done 30M CW.

After all this time, all these dives, and the great course, I have to say that buoyancy is still a daily dilemma for me. Even Martin Stepaneck was left wondering when I dove with him. I can never seem to be happy with my buoyancy: to sum up, I have never ever felt the negative glide down. At best I become "neutral". Sure, at 25M i need a good push off the bottom or tug on the line, but 3 or 4 kicks and I'm starting to float up.

Closely observing my Suunto I am neutral at 10M. I think my problem is that I am afraid to use more weight (horror stories, advice etc). My other problem could be lung volume vs body mass. I have a 7lt VC (I don't pack ever) and weigh 63Kg. I dive with a 7mm suit and now use 7Kg as my suit is getting past the "new buoyancy" phase, during which I used 8Kg.

Often, kicking down to 15M is so tiring that in the quiet of the deep all I can hear is my heart racing at what must be 100BPM. I am sure that only my large lung VC allows me to do longish dives.

I am very conservative, I never have contractions or leg burn, and my surface protocols are very safe and easy.

In a nutshell, should I:
a. try more weight?
b. try less inhale approaching FRC slowly
c. ???

I feel dumb asking the above, but my local club guys just cover themselves with 10Kgs of lead and glide from 5M down. I just can't face to go this route.

THanks.

 

[jome]

Well, here's a few thoughts...

I don't think 25m is a depth where you'd really expect to seriosly freefall, if your buoyancy is set the normal way. So doesn't sound too worrying...You just need to get a little bit deeper

That's a good pair of lungs you have for your size, but with big lungs you'd actually expect a bigger buoyancy change. And given that you dive with a 7mm suit, it should be pretty sharp (in short the bigger the buoyancy, the bigger also the relative change).

But there's no defying physics. Either dive deeper or add more lead and you will freefall. It really is as simple as that.

That said, I think 7kg is a huge amount of weight and 7mm suit in most cases would be a little thick for constant weight. 5 or even 3mm and 2-3 kg weight might a better option?

If you just like to try how it feels to freefall, then yes, exhale less or put on more weight...

 

[dave]

From a spearfishing, rather than pure freediving perspective, I would say you need more weight or a thinner suit. I am quite a bit bigger than you, but I use about 8.5kg with a 5mm. On the very rare occasions I use a 7mm it is more like 12kg (but if I am in a 7mm I am not normally diving deep) I always use a 5mm suit if the temp is above about 9c
cheers
dave
Spearguns by Spearo uk ltd finest supplier of speargun, monofins, speargun and freediving equipment

 

[Bill]

Do the math and you see -2k body and -6k lead needs 8 litres of air for 10m neutrality (@ 63k I presume you aren't fat). That means 8k buoyancy on the surface (16l of air in suit and lungs) and -4k at 30m. At 20m and negative almost 3k you could sink almost 1,5 meters per second with any kind of streamlining. Something just doesn't add up.
Easy answer though. If you have trouble getting off the surface and no trouble getting up, try more weight. To convince your mind that it's OK you might want to take one kilo in each hand and dive in 20 meters. The D3 readout will tell you a lot and retrieving the weights one at a time will be good training.

 

[cdavis]

Hi Azapa,

With your lung capacity, you are a prime candidate for exhale diving. Half lung would cut approximately 3.5 kg off your surface buoyancy but add only 1.2 kg at 20 m. The descent becomes an almost effortless static(you might have to kick once or twice) and the ascent is only slightly harder than what you are doing now. It might even feel easier because your legs will be fresh when you start up.

If the idea appeals to you, search: exhale diving, FRC, Sebastian Murat, and similar. Read every post in the long threads(yeah, it will take a while). Exhale diving is a little tricky and doesn't work for all kinds of diving, so load up on knowledge and go slow.

Let us know how you solve your problem.

Connor

 

[azapa]

Hey, thanks very much for all the great replies.

Jome/Dave: i use 7mm here in Chile because its butt freezing cold. 13C last weekend and 4 hours in the water, and its summer here! I have tried a 3mm suit, it was wonderful, but I was cold in 30 minutes.

Bill: yes i'm skinny, 5'10". I can't follow your math to save my life, but will try again a little later in the quiet of the night

Connor: I will experiment slowly as you suggest. It seems weird, as it must do to all who consider it the first time. I always wondered why seals never packed! (apparently they do partial exhale dives). For some reason though, and bearing in mind my history, I can't even imagine half lung will get me down easily (metal block: I must fight to get down all the time..) The only time I ever tried this was in the Med. No suit, fins or lead, and I could not get bellow 5m no matter what I did. Half lung worked and was relaxing. Not enough time in the med. to improve though

in 10 days I'm will be at the beach and practicing. will report back

good night all!

 

[cdavis]

Weird is putting it mildly. FReaking, bass-ackwards crazy was my first reaction. But, darn if it doesn't work pretty well, no loss of dive time once you get used to it.

Good luck.

Connor

 

[fcallagy]

Hi Simon,
5mm is the way to go Ithink, we have similar water temps and 5mm open cell or smooth skin is fine for hours at a time. The only part of me that usually gets cold first is my feet with 3mm socks. If you are diving to 30m in a 7mm prepare to go deeper in 5mm. I would struggle to get anywhere near that in a 7mm. Also my cressi or Elios freediving 5mms are just as warm as my 7mm scuba suit used to be.