Nothing beats the feeling of floating completely weightless in mid-water. Master achieving and maintaining neutral buoyancy and your diving will move on to a whole new level. You will effortlessly be able to swim around, through and under obstacles; stop to watch or photograph some neat marine life without having to move your arms and legs to hold your position; and hover at your safety stop without moving.
Tracey lying flat above the Zenobia in wetsuit
Are you a newly qualified diver, looking at your instructors or other club members and wondering how the devil they just 'lay there in the water' whilst you are working hard on your buoyancy and being flat in the water?
Are you the one that is thinking about buying some new gear? A new undersuit perhaps, or maybe a seven-litre sidemount cylinder? It's a fair bet that if you get anything much bulkier than a dive computer or a mask and snorkel, then it will have an impact on your buoyancy.
If only I had a pound for everytime someone said "How do you just do that (hovering that is)?" or "My weight was perfect in the sea, then I went to the quarry and went down like a brick!"
For the latter, I can hear you all shouting at the screen as you read this, that the individual in question hasn't removed the 2kg of lead added for the sea before jumping into freshwater, but it's not that simple. Questions like - did they wear the same undergarments for both dives? Where they overweighted on the sea dive but didn't really notice?
Are you the one that is thinking about buying some new gear? A new undersuit perhaps, or maybe a seven-litre sidemount cylinder? It's a fair bet that if you get anything much bulkier than a dive computer or a mask and snorkel, then it will have an impact on your buoyancy.
If only I had a pound for everytime someone said "How do you just do that (hovering that is)?" or "My weight was perfect in the sea, then I went to the quarry and went down like a brick!"
For the latter, I can hear you all shouting at the screen as you read this, that the individual in question hasn't removed the 2kg of lead added for the sea before jumping into freshwater, but it's not that simple. Questions like - did they wear the same undergarments for both dives? Where they overweighted on the sea dive but didn't really notice?
What is Correctly Weighted?
A number of the training agencies have some very simple advice about weighting:
You are correctly weighted when you float at eye level, holding a normal breath, with no air in your BCD at the end of the dive. It's well worth looking at this in more detail if you really want to understand your weighting.
A key phrase is 'at the end of the dive', because your cylinder(s) may have 50bar or even less remaining in them. If you dive with a 12-litre cylinder filled to 232 bar and you are neutrally buoyant at the start of the dive, you will be about 2.6kg lighter by the end of the dive. That is the weight of air you have used. This could be enough to prevent you from being able to stay at your safety stop and control your ascent rate as you near the surface.
In order to be neutral at the end of the dive, you need to be slightly overweighted at the start of the dive. This is okay because your BCD can accommodate the extra air that you will need to get neutrally buoyant. If you use a drysuit then you need just enough air in the suit to relieve the feeling of squeeze - at all stages of the dive.
You are correctly weighted when you float at eye level, holding a normal breath, with no air in your BCD at the end of the dive. It's well worth looking at this in more detail if you really want to understand your weighting.
A key phrase is 'at the end of the dive', because your cylinder(s) may have 50bar or even less remaining in them. If you dive with a 12-litre cylinder filled to 232 bar and you are neutrally buoyant at the start of the dive, you will be about 2.6kg lighter by the end of the dive. That is the weight of air you have used. This could be enough to prevent you from being able to stay at your safety stop and control your ascent rate as you near the surface.
In order to be neutral at the end of the dive, you need to be slightly overweighted at the start of the dive. This is okay because your BCD can accommodate the extra air that you will need to get neutrally buoyant. If you use a drysuit then you need just enough air in the suit to relieve the feeling of squeeze - at all stages of the dive.
Whether you dive dry, or in a wetsuit in warmer waters, getting your weighting right is one of the most-important aspects of diving, and until you have it spot-on, your buoyancy is never going to reach the level you aspire to
Impact of Diving Overweight
For every 1kg of extra weight that someone is wearing, this requires one litre of extra air in your BCD. Surely that air is better used by you to dive with. If you have an extra litre of air in your BCD, it's more to expand and you risk a fast ascent if you are not releasing the air during your ascent.
Holding a Normal Breath
We also need to define 'holding a normal breath'. Most of the time we do our weight checks at the start of the dive, not at the end. Having just entered the water we may not be the picture of elegance and poise we would like to present. Cold water pouring down the back of a wetsuit is guaranteed to cause a sharp intake of breath, as will any anxiety or excitement. Every litre of air that you hold in your lungs produces 1kg of buoyancy.
If you have absolutely no idea how much weight you will need for a dive, then you need an educated guess to get you started. Assuming you weigh at least 60kg and have a single 12-litre steel cylinder:
With a 3mm wetsuit - 4kg
With a 5mm two piece wetsuit - 6kg
With a 7mm wetsuit or a drysuit - 8kg
If you weigh less than 60kg or are very slim (well thats me out then!), remove 2kg from the above. If you are using an aluminium cylinder, then add 2kg.
If you have absolutely no idea how much weight you will need for a dive, then you need an educated guess to get you started. Assuming you weigh at least 60kg and have a single 12-litre steel cylinder:
With a 3mm wetsuit - 4kg
With a 5mm two piece wetsuit - 6kg
With a 7mm wetsuit or a drysuit - 8kg
If you weigh less than 60kg or are very slim (well thats me out then!), remove 2kg from the above. If you are using an aluminium cylinder, then add 2kg.
Completing a Weight Check
Now get kitted up with a full cylinder and do a weight check:
- Enter standing-depth water. Have a few spare 1kg weights to hand in a bag.
- Relax for a couple of minutes, longer if you are wearing a wetsuit so that water gets into the suit and displaces the air.
- Keeping a near-vertical position you should be able to sink. If you can't, double check that you have dumped all the air from your BCD/drysuit.
- Add more weight until you can sink slowly to a maximum depth of 1m. Then descent and hover just off the bottom.
- Now take a full breath in. This full breath should provide just enough buoyancy to begin to lift you off the bottom. Add or remove weight until you can just achieve this.
- If you are using a drysuit, put just enough air into the suit to relieve the squeeze.
- Now relax your breathing and practice, putting air into your BCD if necessary to achieve neutral buoyancy.
- Now go for a dive. At the end of the dive, in standing depth, repeat the weight check. Hopefully you will find that you are more relaxed than you were at the start and not holding much air in your lungs - just enough for a 'normal' breath.
- Now look at where your weights are stowed. The distribution of weights is open to experimentation and can make a big difference to your comfort and trim.
Weight Positioning
For drysuit diving, weights are best positioned at the hips, not above the waist to give the balanced profile/trim. For wetsuit diving, weights are generally best distributed above the hips.”
Points to Remember
Always do a weight check and then keep your weighting under evaluation – we all develop as divers and you may find that as seasons change or you dive better that mysteriously, you need less weight
Keep a log of what equipment you used on a dive, type of water, what weight you used and how comfortable you felt, this helps you to then continue to develop as you move forward.
Keep a log of what equipment you used on a dive, type of water, what weight you used and how comfortable you felt, this helps you to then continue to develop as you move forward.
Struggling with your buoyancy
Do not struggle, if after a few dives you still find that you can't get your weight right, book yourself onto a Peak Performance Buoyancy Course. I have never known anyone who regretted doing that course.
Article version 2.01
Web Updated: 15th July 2021
Released: Club Newsletter: August 2017/ July 2018
Web Updated: 15th July 2021
Released: Club Newsletter: August 2017/ July 2018