Drysuit Buoyancy and Trim: Fixes for Floaty Feet

A drysuit changes how buoyancy behaves. Instead of a wetsuit that slowly compresses, you have a bubble of gas that moves around inside the suit as you change position. Manage that bubble well and a drysuit is warm, comfortable and stable. Manage it badly and you get floaty feet, wobbling trim and the occasional surprise ascent.

Suit or wing: which controls buoyancy?

Use the suit for comfort and insulation, the wing to balance the rig, and breathing for fine buoyancy control. If the wing fails, the drysuit becomes your backup buoyancy. That's a skill you train for.

The wing balances the rig, carrying the weight of the gas in your cylinders and making up for compression. Your lungs make the fine adjustments. The suit only needs enough gas to keep the undergarments lofted and the suit from pinching as you descend.

The more gas you put in the suit, the more there is to move around. Gas in a wing stays on your back. Gas in a drysuit goes wherever is highest.

Why do your feet float?

Because gas rises. If your feet drift above your hips, gas flows into your legs and boots and lifts them further. The usual causes:

• Too much suit gas. The most common cause.
• Head-down trim. Even a few degrees sends gas toward your feet.
• Loose legs or oversized boots. Extra volume gives gas somewhere to collect.
• Very light fins. They don't counter the lift in your feet.
• Not venting on ascent. Expanding gas has to go somewhere.

How do you fix floaty feet?

1. Use less suit gas. Add just enough on descent to stay comfortable.
2. Stay horizontal. Head-down trim sends gas to your feet. Catch it early.
3. Check suit and boot fit. Excess volume in the legs is worth fixing at the source.
4. Check your fins. Very light fins make floaty feet worse. But fix the suit gas first. No ankle weights.
5. Vent regularly. Keep the shoulder dump where gas can reach it, and vent a little at a time on ascent.

How should you weight for a drysuit?

Undergarments trap air, so most divers need more lead in a drysuit than in a wetsuit. Do the end-of-dive weight check with your actual suit and undergarments: at a shallow stop with a nearly empty cylinder, an empty wing and just enough suit gas to avoid squeeze. See How Much Weight Do I Need?

A drysuit is also a second source of buoyancy. That's why UTD requires a balanced exposure system such as a drysuit with steel doubles. In my classes, steel never goes with a wetsuit. See What Is a Balanced Rig.

What emergencies should you train for?

UTD's drysuit course covers the failures that matter:

• Loss of the inflation system
• A minor leak and a major leak
• Recovery from gas in the feet
• A stuck or lost exhaust valve

Each has a practiced response, and each is far easier to handle the second time than the first. Learn them in a course, in calm water, with an instructor.

Diving dry in San Diego

San Diego water is cool all year, and colder below the thermocline than at the surface. Many local divers dive dry year-round, especially for long dives, repetitive dives and training days. UTD's drysuit course recommends electric heating, and a heated vest makes a long day in the water far more comfortable.

For water temperatures by month, see San Diego Water Temperature by Month.

Learn it properly

Our Drysuit Diver course covers drysuit buoyancy, trim, emergency procedures and suit care. For the fundamentals that every drysuit skill builds on, see How to Master Scuba Buoyancy.