We’ve all faced the problem of changing one aspect of our kit and then finding our weight and trim is all wrong. It happened to me recently when I switched to a semi dry suit.

The other problem more experienced divers face is that they can easily compensate for being over or under weighted, but this can lead to excess air consumption, fatigue and less enjoyment on a dive.

So it seemed like a good time to re examine the correct way to set your weights up. The essence is to find the correct weight and then trim it so that you can move around underwater effortlessly.

Weight

PADI teaches that for correct buoyancy, you should be able to sit at the surface at eye level with no air in your BCD.

The mistake is that most people check this at the start of the dive, and it should be at the finish.

At the start, with a full cylinder, you should very slowly sink with no air in your BCD, and remembering to breathe through your regulator.

If that’s the case, then you’ll find by the end of the dive, with only a little air left, you will be just buoyant.

Trim

Many divers put lots of effort into weighting, and then forget about trim – which is almost as important! Without proper trim you can end up moving through the water far too upright, which expends extra energy, or rolling around when you don’t want to. In cave situations, it can be positively dangerous.

Here’s how to test your trim:

• Descend to five meters and get your buoyancy neutral.
• Put your body in a face down swimming position, arms folded and knees slightly bent.
• Now hover for a couple of minutes taking shallow breaths.
• Don’t fight what happens, simply note it.

If your body moves up and your feet move down – your centre of gravity is too low, and you need to shift weight up – ideally using trim pockets.

If the reverse happens, you need to shift weight lower on your body – perhaps through ankle weights.

If you start to roll – this can often be caused by having a lamp or console on one side - then compensate with small weights on the other side.

Finally, remember to repeat this whenever you change equipment or configuration.

Here are some other posts you may enjoy:

1/ How to use a surface marker buoy

2/ Overcoming diving fear

3/ Medical Mick’s scariest diving accident