How to Deploy an SMB From Depth

A surface marker buoy tells boats and the surface where you are before you get there. Deployed well, it is a controlled task performed at the depth and time agreed in the dive plan. Deployed badly, it's how divers lose their stop, tangle their gear or get pulled toward the surface by their own buoy.

Why deploy an SMB from depth?

Sending the buoy up before the ascent, rather than at the surface, does three things:

• It marks your position for the whole ascent, so a boat knows divers are coming up underneath.
• It gives you a visual reference while you hold your stops in open water.
• It lets a live boat follow the team on a drift dive.

That's why UTD's minimum equipment for its open-circuit classes includes an SMB and a spool with at least 70 feet of line. Gardner Underwater's course checklists ask for 100 feet; confirm the length on the packing list for your course.

What do you need?

• An oral-inflation SMB, as specified for UTD's SMB MINI, sized for the conditions. Learn the inflation method for the actual buoy while maintaining a working breathing supply.
• A spool with a bolt snap, carrying enough line for your deepest planned deployment.
• A place to stow them where you can reach them without rolling: a thigh pocket on a drysuit or a pocket on your harness.

Pre-rig the buoy on the spool before the dive, so deploying it is a matter of unrolling, not assembling.

How do you deploy an SMB, step by step?

1. Tell the team. Signal that you're deploying, and wait for the team to be ready and in position. One diver deploys; the others hold position close by and watch.
2. Get neutral and stable. Stop moving, get horizontal and settle your buoyancy before you touch the buoy.
3. Unstow the buoy and spool. Unclip the spool, keep a few feet of line free and unroll the SMB in front of you.
4. Check the line is clear of your hoses, fins and light before any gas goes in.
5. Add a small amount of gas. Fill the buoy enough to stand upright, then let it go. More gas isn't better at depth; it expands on the way up.
6. Let the spool run freely. Hold it loosely in your hand, away from your body, so the line pays out without catching.
7. Monitor depth, breathing and the line together. Use the inflation sequence learned for your buoy, keep a working breathing supply and manage any buoyancy change. Teammates watch position and entanglement while you deploy.
8. Lock the spool once the buoy reaches the surface, keep light tension on the line and reel in as the team ascends through its stops.

The skill UTD tests is simple to describe: deploy the SMB from a neutral position, make a normal ascent, and recover the buoy.

How do SMB deployments go wrong?

If a jammed spool is pulling you upward, release the hand-held spool rather than accept an uncontrolled ascent. Releasing it will not clear a line already wrapped around you or a teammate; practice line-failure responses and keep cutting tools accessible.

Spool or reel?

Use a spool. It's small, has almost nothing to jam and can be dropped instantly. Reels belong to guideline work in caves and wrecks, where you need long lengths of line and a handle to manage them. For a marker buoy, a reel adds bulk and a jam point without adding anything useful.

When should you deploy it?

Your plan decides. On a drift dive with a live boat, the team may deploy before leaving the bottom. On other dives, the buoy usually goes up at or before the first stop. Agree on when and who in the pre-dive briefing: UTD's dive plan names a leader who leads the ascent and deploys the SMB.

Practice it before you need it

Practice at a comfortable depth on easy dives until it's boring, then practice in mid-water with the same neutral control. The bottom is a visual reference, not something to brace on. Video is especially useful: most people don't realize how much they move while filling the buoy.

Our SMB Extension is built around this one skill. SMB deployment is also part of Essentials of Recreational Diving. For how the team supports the deployer, see Team Diving vs Buddy Diving.