"Better to be on the boat wishing you were diving, than underwater wishing you were on the boat."

Augusto Pavan

AUTOMATIC SAFETY BUOY
A compact, ultra-fast deployment buoy system for emergency use underwater

Overview

During recreational dives, especially with beginner divers (OWD), I noticed how long and complicated it can be to deploy a surface marker buoy (SMB) in an emergency.
This inspired me to design a fully automatic system: just press one button, and the rest happens by itself — no manual inflation, no fumbling with reels, no training required.

Design Philosophy

From the beginning, my goal was simplicity, reliability, and accessibility:

One-button activation – usable even with thick gloves or in zero visibility.
Ultra-fast deployment – fully inflated and ascending in under 2 seconds.
No maintenance – uses disposable CO₂ cartridges, no refills or servicing.
Compact & lightweight – fits in a BCD pocket, weighs <200 g.
Affordable – total build cost under €20, versus ~$200 for commercial devices.
Open-source design – anyone can build or modify it.

This device is not meant to replace a standard SMB during normal dives — it’s a backup system for emergencies, when speed and ease of use are crucial.

This project was originally discussed with a French dive gear company, but after a week of collaborative refinement it was not pursued commercially.
I’ve decided to share the entire project freely, open-source, for anyone to build and improve.

HOW IT WORKS

A lever triggers a small steel pin that punctures the CO₂ cartridge, releasing gas that rapidly inflates the buoy.

FIRST PROTOTYPE

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Here the complete project and presentation about first prototype

Safety and Reliability

The system has no moving parts during storage, reducing risk of accidental activation.
It is mechanically triggered, not electronic — works even with dead batteries or after years in storage.
It is not intended as a primary SMB: always carry a standard buoy for planned ascents.
This design is experimental and for personal use: test thoroughly in controlled conditions before real dives.

What you see here was the very first prototype.
Through testing, real-world use, and countless small improvements, the design evolved into the current Rev. 12 —
now reduced to its essence: a single 3D-printed body and a basic steel nail as the firing pin.

Components and Materials

ComponentDescriptionNotes
Buoy tubePolyurethane inflatable tubeFrom Decathlon (€4.99)
ValveMushroom-style one-way valveFrom Quechua camping mats (€2.99)
CO₂ cartridge16 g disposableStandard bike tire cartridges
Firing pinSteel nailPicture-frame nail works
Spring1 cm compressionAny hardware store
Cartridge supportAlloy 6071 or brass (⅛” 24 thread)Custom 3D part
Body3D printed (PETG-CF or resin)Printable on consumer printers
Cord (optional)10 mTo keep connection with diver

Total cost of all parts: < €20

LAST VERSION

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FULL DRAW

BODY .STL

PLUG .STL

TRIGGER .STL

REEL .STL

SOLIDWOKS MODEL

Recreational diving safety often overlooks the human factor under stress.
Even experienced divers can struggle with fine-motor tasks when panicked or disoriented.

The Automatic Safety Buoy solves this by reducing the task to a single gross-motor action: push a button.
This could save precious seconds in a real emergency — and possibly save lives.

It also demonstrates how innovation can come from individual divers, not only from large manufacturers.
By sharing this design freely, I hope to inspire others to experiment, innovate, and contribute to safer diving practices.