Low visibility and buoyancy

[g1138]

In terms of feeling inconsistent with your weighting and descending, you may be unconsciously finning at the surface. Or your suit may be too new. I used to have to pike dive or kelp dive to get under. Now that my suits a year old I find myself sinking a bit better, but I still hover just below the surface when I'm fully deflated at the start of my dive.

 

[TSandM]

For descent, try this: You are vertical in the water, and you raise your inflator to begin to exhaust air. Kick up a tiny bit, and INHALE. As you come down far enough that your face gets into the water, EXHALE HARD and hold it as long as you can. At the same time, be absolutely sure you are not kicking. You will slip under the water, and as your suit begins to compress, you will easily stay there.

A lot of divers push the exhaust button on the BC and exhale . . . but if you do that, by the time your face gets to the water, you may well need to inhale again, and back up you go!

With regards to the buoyancy in midwater thing -- this is a difficult skill indeed. Descending in very poor viz is a serious challenge, unless you know precisely how deep the water is where you are going. Transitioning to a horizontal posture early in the descent helps, because at least then your face is aimed downwards . . . but in very poor viz, I have hit the bottom before I saw it, or at least I saw it so late I couldn't arrest my descent in time to avoid it. (Those are the days I consider aborting and going to lunch . . . )

To me, there are three keys to stability in midwater. One is that you have to have your rig balanced so that you can trust that, if you stop moving altogether, you will remain horizontal. If your rig tilts you feet down, then any movement you make in the water whatsoever is going to drive you shallower. You have to trust your "horizontalness".

Second, you have to have your breathing under absolutely rigorous control. If you become anxious because you can't see, you will hold more air in your lungs, and you will go up. Breathing has to be divorced from everything else you are doing in the water.

Third, you have to develop references. A good wrist computer that you can easily SEE is a constant reference. The particles in the water are a good reference, except in up and down currents. Learning how your gear feels on your back can help -- when it starts to feel light, you're going up. Your ears should tell you about going down. But the absolute BEST reference is a rock solid buddy.

This skill takes practice, and I would not be unhappy with yourself one bit if you didn't shine at it on your first attempt. It took me YEARS of practice in Puget Sound, to learn to make a really good, accurate ascent (although I figured out early on how to make a 20 foot stop -- it didn't matter if I thought I was doing somersaults, so long as I was doing them at 20 feet).

Avoid any rapid head motion when you are in very low viz with no reference -- it can provoke vertigo, and that's no fun at all.

Don't despair -- if diving didn't have challenges in it, what fun would it be?

 

[Pullmyfinger]

You have to trust your "horizontalness".

A pearl of wisdom.

-Mitch

 

[Frosty]

as an aside. Airline pilots with thousands/tens of thousands of hours of experience have got totally disorientated when in zero vis. In that case you just have to have 1000% confidence in your instruments.
in an aerobatic light aircraft Ive been hung upside down off my harness with no idea which way is up down or sideways except for the lil round gauges in front of me.

 

[Searcaigh]

Was the lake fresh water?

Were you weighted for salt water?

Frequently novice divers forget to adjust weighting for differences in salinity, I require another couple of pounds when diving in the cold Gulf of Aqaba during winter

 

[DwayneJ]

Tiny particles in the water 6-12" from your nose are a great indicator and wil assist to provide you with a visual reference. I would also strongly recommend learning how to shoot a SMB with a finger spool since your dive is pretty much over with such poor vis.

Dwayne

 

[James R]

I dove there yesterday, and conditions were pretty bad, but are improving from what they were a few weeks ago. The wind and chop at the shore made shallow viz poor and the lake turning over is making it crap at depth too.

Last year conditions this time of year were similar, then a month later we had viz of 12-18' at depth - so in June it should, assuming it changes like last year, be warmer and much better all around.

Keep an eye on this thread for updates on conditions at Lake Travis (and other TX sites). People update it pretty often.

 

[Blue Sparkle]

I'm still at a loss as to how I can feel over-weighted on the bottom, yet have trouble getting under in the first place.

Do I remember correctly that you are wearing 7mm or more of neoprene? If this is the case, then even if you are properly weighted, I believe you will feel a bit "heavy" when you are at depth - especially near the beginning of the dive when your tanks are full.

If you think about it, you have to weight yourself so that you can hold your safety stop near the end of your dive with "light" tanks (say around a 6# difference between full of air and empty of air), and with your wetsuit somewhat "re-fluffed." Let's say the difference between "fluffy" and compressed on your suit is another 6#. That means you are "overweighted" by about 12# through much of the first part of the dive (especially given that you often do the deepest, most "compressive" part of the dive early on when your tanks are full/heavy).

At that point, you pretty much have to compensate by putting air in your BC. So I wonder if that is why you are feeling overweighted?

(Mind you, you may BE overweighted. I'm just saying that even if you are perfectly weighted, I think that when you are wearing a thick wetsuit you are going to be "heavy" at the early/depth of the dive.)

The other side to that coin is that your wetsuit is fully "fluffy" at the beginning of the dive. So when you start to descend (as TSandM gave a good method for), you will be "fluffy" (and there may be air pockets in your suit), and then there will come a point where the suit starts to compress and you'll feel a moment of "oh, now I'm sinking!" Then "sips" of air into your BC can make it all gradual and smooth-like, especially if you stay slightly ahead of the curve.

Okay, at this point in the post I'm hoping I have not said anything totally wrong. And... I have only dived with a 5mm, but it definitely feels different compared to diving with no exposure protection.

 

[Searcaigh]

I have only dived with a 5mm, but it definitely feels different compared to diving with no exposure protection.

That is for sure, I am about to cast off my 5mm semi dry now and don my 3 mil for the summer. Can't wait to reduce my weightbelt too.

 

[Bubbletrubble]

@TexasKaren68: Why wonder whether you are over-weighted or under-weighted? Just conduct a proper weight check. It's simple. It only takes a couple of minutes to do. If you change your wetsuit/tank, switch from conventional BCD to BP/W, or move from freshwater to saltwater (or vice versa), you really should do another weight check. Novice divers who are renting "new" gear should be doing weight checks before every dive. It's a good habit to get into. If your tank is not empty at the time of the weight check, make sure to compensate for the remaining gas in the tank.

Being properly weighted is a separate issue from establishing neutral buoyancy at depth. For example, you can over-weight a diver with 10 extra pounds, but he/she should still be able to get neutral at depth by adding an appropriate amount of gas to the BCD and/or drysuit. Having that extra gas inside the BCD/drysuit may make it more difficult to manage expansion of that bubble during ascent, however.

As others have already pointed out, in low vis conditions, it's critical to be able to trust and reference your depth gauge. It's also very important to maintain proper buddy contact. This may mean moving slowly, not changing directions suddenly, frequently checking on your buddy's position, clearly communicating dive signals to your buddy (e.g., putting your hand in front of your buddy's mask), swimming shoulder-to-shoulder, holding hands, or even linking arms. Using these methods, it's possible to even keep a 3-person buddy team together in low vis conditions.