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Remaining Neutrally Buoyant

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Hi,

 

I have always been impressed with the technique some have (not me ;) ) of remaining neutrally buoyant in mid-water while snapping a shot. Especially when you consider the factors of having a negativly buoyant camera rig, a drysuit, and surge.

To preface this post, I certainly haven't taken any courses in buoyancy but the PADI "Perfect Buoyancy" class should probably be high on my priority list :D

I prefer to get down low (as it appears that I have no choice) and shoot upward. I carefully select sandy patches at the edge of a reef where there tends to be more available light and I can include a colorful backdrop. In cold water enviornments, the reefs tend to have a canopy of kelp which although beautiful when shooting upward, doesn't let too much light pass thru them. Also I don't care too much for the "airplane view" of a reef where you only see the tops of fish, coral, and small critters. However, I could certainly see the advantage of attaining neutral buoyancy when diving a wall or trying to capture an open water pelagic.

In our open water courses that we've all taken, we were taught to achieve neutral buoyancy. Once neutral, a breath or an exhalation would change your depth in mid-water. We are also encouraged to take take "long slow breaths" which IMO doesn't help since your constantly moving up and down in the water column. For UW photography breath control is essential in being able to capture your subject. Here's my question (finally)..... Since you rise with a full breath of air and sink with a full exhalation, for UW photography do you take half breaths to remain neutrally buoyant in mid-water?

Any tips on this matter would greatly be appreciated.

 

Thanks alot

Vance

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You're taught not to do it but I hold my breath when I need pinpoint bouyancy control.

 

I haven't really thought about it, but my regular breathing pattern has me with air in my BC to make me neutral with half full lungs; I take in a deeper than usual breath and hold it a bit longer if I find myself getting a foot or two too deep, and the opposite if I'm a couple of feet shallow.

 

Wearing a drysuit improves your ability to percieve depth changes, especially in open water.

 

The best way to get better is to think about it on every dive, and actively practice even when you don't need to. Like at safety stops, where you should be able to hold depth within a 2 inch range without finning. Do this and you'll notice an improvement in just a few dives, I'll wager.

 

A good assessment is the "30 second test". If you can hold a horozontal position and depth for 30 seconds without moving a muscle, your trim and bouyancy is good.

 

Also, if you can avoid the brainwashing of the one right way, a DIR-F class is a great tool for just what you are asking about. Keep in mind the "class" is more of an "exam", and there may not be as much "teaching" as you may wish for.

 

All the best, James

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I find that if I'm overweighted my buoyancy control is bad. I'm not sure why but the corrections seem to be larger. Whereas when I'm properly weighted, a little exhale or inhale can have instant results. I know this isn't always a good thing but I usually find a place to put my finger which isn't damaging to the reef. If I can't find a place, I'll take the best picture I can and then move on.

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I cannot comment on cold water or drysuit diving; but in Florida / Carribean I love to dive with a 100 ft HP steel tank, which for me means 0 - 4 lbs of weight depending on thermal protection. I then dive most of the dive with little or no air in the BC. This way there is very little variability in my buoyancy at various depths due to the BC - so I do not have to mess with the BC at all. Buoyancy is then all related to breath control.

I think that we frequently have to break the rule of breath holding while preparing for a shot. Also of course it helps to get closer to our subjects on many occasions too.

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I agree that the key is to be as neutral as possible without air in the BC then a simple full breath in pushes the "up" button and the opposite to go down. I find myself exhaling when I need full control for a shot.

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I think macro photography is actually a great way to learn good buoyancy control.

 

I was amazed at how fast my buoyancy control improved when I started hunting nudibranchs with a macro lense in a field of sea urchins in surge. I think I improved like 50% just during that one first dive among the urchins! Necessity is the mother of invention. :-)

 

And to answer the breathing question, the advice to take slow deep breaths was what I got in OW training too, and it turned out to be the opposite of a good idea. Taking and releasing a full breath will send me up/down about five (yup, five!) feet. (I think it depends on how much your body volume expands when you breathe in - some people it's not so bad). Now I just do my regular breathing - slow, extremely shallow breaths. I'd say I breathe from 1/3 lungfull to 2/3 lungfull and back again, or maybe more like 2/5 to 3/5. If I notice I'm too high or too low, I'll just take a full breath or completely release breath and wait a couple of seconds to accomplish the correction.

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lots of outside elements can effect neutral bouyancy and we,ll look at them later. I do a lot of dive instructing in England, and once I feel confident that my students have mastered the idea of how to get neutral bouyancy at different depths,and they are completely comfortable using their kit to achieve this,then the teaching method changes.

 

BACK TO BASICS: Rule no 1."There is no such thing as Neutral Bouyancy".

 

Most peoples idea about neutral bouyancy is that some people can pick a spot at a certain depth and stay rooted to that spot and depth no matter what they are doing.Whereas the rest of us mortals know that the moment we breath in we'll be shooting to the surface,or breath out and your heading for Davey jones locker.To achieve the appearance of neutral bouyancy the trick is to breath at the right time.

 

Try this in the pool or a local shallow dive spot,lay face down on the bottem and inflate your jacket to where you think you are neutral, breath in and you start to go up.BUT what I want you to notice is the time delay between you breathing in and your body starting to move off the bottem,the delay is happening because the size and shape of your body in this horizontal position is trying to push its way up through the water column in this positivly bouyant state.

Now,when you are approx 2ft off the bottem, breath out and notice that, again, there is a time delay,once you have breathed out your body will slowly come to a stop,and then start to sink back down to the bottem, this delay is happening for several reasons.

1. Once an object starts to move it has to slow down befor it stops.

2. the amount of air that you put into your jacket at the start of the exercise has expanded a little as you floated up making you fractionally more bouyant.

 

I know that 99.9% of the people looking at this will recognise it as probably the first exercise they ever did in the pool when they were learning to dive, but how many people noticed the time delay between breathing action and reaction. We are going to use this delay to our advantage to achieve apparent neutral bouyancy.

 

Imagine we're still on this practice dive, go back down to the bottem but this time sit on the ground with your legs crossed, achieve neutral bouyancy again using your jacket,then hold on to your fins with each hand, now breath in and you will start to rise,

2ft off the bottem, slowly breath out you will slow down and start to sink, but this time just as you are starting to sink, start breathing in, the sinking will slowly stop. When you start to rise again,slowly breath out. Practise this for a while, you should be hovering above the sea bed/pool floor while apparently breathing normally, this is Neutral Bouyancy and with more practise this technique can be fine tuned untill it looks effortless, and will illicit admiring glances from other divers around you.

The sitting position that was mentioned at the begining of this paragraph is used to stop my students flaping their arms and legs about and concentrate on just the bouyancy. You may find that in this position you will roll onto your back as soon as you leave the bottem, that's alright, just concentrate on the hovering, but when I am teaching this exercise it nicely flags up the importance of weight placement on your belt or integrated jacket. If you get the weight placement right and you find that you can hold an upright position while hovering, it's a great trick on a gentle drift dive to go slowly drifting by your fellow divers looking like some sub-aquatic budda.

 

Other things to look for that could ruin your bouyancy are:

 

Aluminium tanks - the difference in weight between a full aluminium tank and an empty one is quite large, enough to make the difference between having enough weight at the start of the dive and being unable to stop floating to the surface at the end of the same dive.

When on overseas trips the first dive of the trip should always be a"check-out dive." When this dive is completed I will insist on jumping back into the water with a tank that is "on reserve" to check that my weight is correct, it only takes a minute. Once in the water, deflate jacket with your lungs full, if you sink at this point you are overweighted, if not slowly breath out. allow yourself to sink below the surface by 2ft then come back up, job done.

This first dive should be done without camera even though sods law states that you are going to have to swat the manta rays out of the way in order to see the whale shark.

Every other diver on one of my liveaboard trips told me they could hear every swear word as clearly as if they were on land when this happened to me.

 

Get your camera as neutral as possible, it will be fine when you are swimming around but as soon as you try and bring it to your eye a heavy camera's weight can cause you to swing head down in the water.

 

Don't get caught out with Kilo's and Pound's when ordering your weights on trips.

 

And remember, Overweighted can be just as bad as underweighted

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As everyone has said, the biggest trick being neutrally boyant is to not be over-weighted. If you are not over weighted, staying perfectly neutrally boyant while you compose your shot is really very easy, wile you are looking through the viewfinder, you just hold your breath at the point where you are neutral.

 

However being neutrally boyant is not enough. If you wish to hover motionlessly you also must not rotate in the water.

 

Naturally my legs sink and my head floats up. If I stop swimming, I end up orientated vertically in the water. My head toward the surface, my feed by the sand. Other people are the opposite their legs float and their head sinks. Either way, even though your body as a whole is not sinking or floating, you don't stay still when you stop swimming.

 

The key here is to get some weight off of your waist.

 

If you are a leg floater, you're going to need to move some lead closer to your feet. A heavy camera is going to exagerate your problems, so you want a posatively boyant camera which will also to keep your head up.

 

If you are a leg sinker you need to move lead closer to your head (I strap my lead to the top of my tank). Here a heavy actually camera helps keep your head down and your feet up.

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Often heard during buoyancy discussions is “don’t be overweighted†or “you need to remove weightâ€. This is actually connected to ability to be neutral underwater only in a remote sense.

 

As long as I wasn’t overweighted by a boat anchor’s worth, I would be more concerned with trim, as acroporas notes above.

 

I think a bit of perspective is a good thing.

 

I occasionally dive with more weight in gas than most divers have on a weight belt; I can emphatically say this “extra 20 pounds†causes me no difficulty in becoming neutral and hovering in place.

 

My experience is that correct weighting will result in a neutral diver, at the surface with an empty cylinder(s) and empty BC. Amazingly, there is a supposition that the lighter the belt, the better, and thus implies a better diver. For me and those I dive with, a couple pounds too light is almost worse than a couple pounds too heavy.

 

For example, consider a dive that went too deep/long, resulting in deco. When the poor diver arrives back at stop depth, their cylinder will be quite low on gas, and thus buoyant. A diver that is too light will have difficulty holding stop depth, especially the longest one, at 10 feet. Also, I consider the ascent from 10’ to the surface to be the most critical, being the one with the greatest ratio of pressure change. So, I try to “squeeze off†the ascent, by taking at least a minute or more to cover that last 10 feet, to give good shape to the curve, something that is nearly impossible if too light.

 

Yes, yes, it is true that excess weight can cause a slightly greater ratio of expansion in the BC when ascending. This is easily managed in the most part and the effect is usually overstated. 4 pounds extra is really not a big deal. Sheesh.

 

In the tropics, wetsuit compression at 80 feet will usually result in a roughly 10 to 14 pound negative force on the diver; yet, we have no issue with hovering, adjusting up and down with lung adjustments, or swimming up 20 feet and readjusting to neutral.

 

I would submit that a diver that is at 40 feet, early in the dive with practically no air in the BC, is actually incorrectly weighted by being too light.

 

Weighting is applicable in a global sense to the conduct of the dive. Being neutral is more of a balancing act at a point in the dive.

 

All the best, James

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Good discussion. I support the view that negative at the end of the dive is best. An AL80 is about 6-8 positive at 500# and that's a pain to fight when one wants to fool around in 20 feet of water for the last few minutes of the dive. As a beginner, I've been that light many times at the end of a dive, but not any more. Besides, my BC has 40# of lift, never use that much in the tropics. With a 3mm shortie, I use about 14 pounds of lead, unless I've gained fat or methane.

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Interesting discussion...

 

I have moved into a SS backplate for ALL my diving. Warm water or cold.

I've also moved into a small 18# rear bladder. Not much lift I agree but enough to get the job done.

 

The upside of this is that the majority of the weight is rignt next to my body and is distributed evenly.

in cold water I dve with a Steel 80 and 2lbs more weight and in warm water I have no extra poundage.

Very little air is required in either case to trim me out.

 

The downside of this is that with my steel tank I tend to "turtle" a bit if I am horizontal and completely relaxed and the extra travel weight is a bit of a pain but the simplicity of a single strap and backplate are worth it.

 

I'm sure many of the DIRers out there will point out that In the case of a bladder failure I may end up heavy at the bottom and without any weight to ditch but my SMB has about 60# of lift for such an emergency.

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Neutral buoyancy is, in my opinion, all about experience and determination!

 

I use 13 Kg + ankle weights in fresh or seawater (totally wrong I know) and don't have any problem being neutral in either. On Saturday I tried a new drysuit, with all my other kit as normal, in cold freshwater and came to my neutral halt at about a meter above the quarry bottom as ever (at ~17m). The ability to maintain neutral buoyancy is not about 'perfect' equipment nor 'precise trim' (IMHO) but a lot to do with your own experience level and more to do with your own desire to deal with buoyancy - many divers never seem to (most are not photographers after all) and as they don't need to be perfectly neutral it doesn't seem to worry them overmuch - they are 'acceptably' neutral but nothing more. Photographers need far more accurate buoyancy control than most other divers and by being conscious of this, striving to achieve neutrality and gaining experience, good neutral buoyancy skills can be attained. Breath-holding comes with the territory!

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