Mastering Buoyancy Control in a Drysuit: The UK Diver's Complete Guide

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Your first drysuit dive feels wrong. The suit squeezes you during descent. Air shifts to your feet during horizontal swimming. Your legs suddenly float up, inverting you. You struggle for control while your instructor looks on calmly.

Welcome to drysuit diving. It's harder than wetsuit diving, more complex than you imagined, and absolutely essential for year-round UK diving.

Mastering drysuit buoyancy control takes 10-20 dives. Here's what you need to know.

**Why Drysuits Complicate Buoyancy**

Wetsuits trap tiny air bubbles in neoprene cells. Small air volume, distributed throughout the suit. Compresses at depth, expands during ascent, but changes are gradual and manageable.

Drysuits contain a large air bubble that shifts dramatically with body position.

Go head-down and air rushes to your feet, creating massive positive buoyancy in your legs and inverting you. Horizontal swimming shifts air unevenly between chest, arms, and legs. Depth changes compress or expand this air significantly.

You must also manage two inflation devices: your drysuit and your BCD. Each affects buoyancy differently. Most drysuit problems come from using both simultaneously, creating confusion.

The Fundamental Principle

Use your drysuit for buoyancy control. Use your BCD as backup only.

Add only enough air to your drysuit to eliminate squeeze and maintain comfort. You should feel no suit pressure against your body, but suit shouldn't be balloned. This is minimum air for comfort.

Make fine buoyancy adjustments with breath control and small drysuit vent burps. Inhale deeply to become slightly positive. Exhale fully to become slightly negative. Vent tiny amounts of air for fine-tuning.

Only use your BCD if: Your drysuit fails completely. You need surface flotation. You're new and struggling (transitional phase only).

Using both systems simultaneously makes precise control impossible. Stick to drysuit-only buoyancy.

Weight Configuration for Drysuits

Most UK drysuit divers need 10-15kg of lead, though this varies enormously.

Start with your 7mm wetsuit weight plus 4-6kg for typical undergarment. Crushed neoprene drysuits need less weight than membrane suits with thick undergarments.

Proper weight check: At surface in full kit, empty your BCD, add minimal air to drysuit (just enough to eliminate squeeze). Hold normal breath and float vertically. You should float at eye level. Exhale fully and you should sink slowly.

Test at END of dive when tank is near-empty. Full tanks have 2-3kg positive buoyancy. If you're correctly weighted at end of dive, you'll be slightly heavy at start (manageable). If you're correctly weighted at start, you'll be dangerously buoyant at end.

Many UK divers carry too much weight. Excess weight requires excess drysuit air, which compounds control problems and creates "runaway feet" inversions.

Weight Distribution Matters

Poor weight distribution causes trim problems and makes buoyancy harder.

Integrated BCD weights (4-8kg): Provides central mass, easy ditching, good starting point.

Weightbelt (remaining weight): Position low on hips, NOT natural waist. Low positioning helps keep feet down.

Ankle weights (1-2kg per ankle): Counteracts drysuit air in feet, prevents inversion. Excellent solution for many UK divers.

Tank positioning: Higher on back creates head-heavy trim. Lower creates feet-heavy trim. Adjust for your body.

Many UK divers use combination: 6kg integrated BCD, 4kg belt, 2kg ankle weights (12kg total).

Trial different configurations in pool before open water.

Stopping Feet-First Inversion

Feet-up inversion happens when air migrates to your legs and feet, creating uncontrolled positive buoyancy.

Prevention: Carry minimum necessary weight (excess weight needs excess air, compounding problem). Stay rigidly horizontal at all times (air in horizontal tube stays distributed, air in vertical tube rushes to high point). Use ankle weights to counteract foot buoyancy. Vent aggressively if you feel feet rising. Never go head-down until you have excellent control.

If inversion begins: Tuck into ball position immediately. Grab your knees, pull yourself into tight ball. This shifts air from feet toward your core. Vent air aggressively from shoulder dump. Once horizontal again, add minimal air back.

Some drysuits have leg dump valves. These help manage inversions but aren't standard.

The permanent fix is reducing total weight and improving trim. Feet-up indicates you're overweighted, not that you lack skill.

**Depth Changes and Buoyancy**

Descent: Your drysuit compresses. Squeeze develops. Add small amounts of air to eliminate squeeze. Don't overinflate. You should feel no pressure but suit shouldn't balloon.

At depth: Make fine adjustments with breath control. Ascending 1-2m? Big inhale. Descending 1-2m? Full exhale. Vent tiny amounts of drysuit air for bigger adjustments.

Ascent: Expanding air makes you progressively more positive. Vent continuously during ascent. Small bursts, constantly. Don't wait until you're rocketing up. By then it's too late.

Safety stop: This is where most drysuit problems happen. You're shallow (5m) where air expands maximally. Small depth changes cause large buoyancy swings. Stay horizontal, vent preemptively, use breath control for fine-tuning.

Learning Progression

Dives 1-5: Everything feels wrong. You fight for control. Frequent inversions. Frustration is normal.

Dives 6-10: Control improves. You're anticipating depth changes. Inversions less frequent. Venting becomes more automatic.

Dives 11-20: Buoyancy feels natural. You're making micro-adjustments unconsciously. Hovering motionless is easy.

Dives 20+: Drysuit control is automatic. You can focus on the dive, not your buoyancy.

Most UK divers struggle for 10-15 dives, then suddenly "get it." Persist.

Seasonal Adjustments

Undergarment thickness dramatically affects buoyancy.

Thin summer undersuit (200g): 8-12kg weight typical.

Thick winter undersuit (600g): 12-16kg weight typical.

Change of 4-6kg between summer and winter configurations.

Always do full weight check when changing undergarments. Record your weight configuration in logbook for each undersuit.

Troubleshooting Common Problems

Constant squeeze despite adding air: You're underweighted. Suit compresses at depth, you add air to eliminate squeeze, but suit re-compresses. Add 1-2kg weight and retest.

Constant feet-up: You're overweighted. Reduce total weight by 2kg and add 1kg ankle weights.

Runaway ascents: You're adding too much air. Use minimum air for comfort. Vent more aggressively during ascent.

Can't stay horizontal: Weight distribution problem. Move weights lower. Consider ankle weights. Adjust tank position.

Breathless feeling: Drysuit squeeze compressing chest. Add more air until you can breathe comfortably.

Pool Practice Drills

Before UK open water, practice these in confined water:

Hover motionless at 3m for 5 minutes. No fin movement, no hand movement. Breath control only.

Ascend and descend through 2-4m range using only breath control. No suit inflation/deflation.

Swim horizontal circuits at constant depth. No depth variation.

Practice inversion recovery. Roll inverted deliberately, recover using tuck position and dump.

Roll 360° while maintaining depth. Air shifts but you stay horizontal.

These drills build muscle memory before challenging UK conditions.

The Reality

Drysuit buoyancy is hard. Harder than certification courses suggest. Harder than tropical diving wetsuit control.

But it's learnable. Every UK diver struggled initially. Every competent UK diver now finds it automatic.

Give yourself 15-20 dives to learn. Don't expect perfection on dive 3. Accept that you'll have frustrating dives where control feels impossible.

Then, around dive 12-15, it clicks. Suddenly you're hovering motionless. Your buoyancy is automatic. You can focus on wrecks, seals, photography, whatever you came for.

That's when UK diving becomes truly enjoyable.

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