Marking the registration of a vessel complies with specific regulations. We speak of internal marking (at the helm station or in the cabin) and external marking (on the hull).
Internal marking
Since the 1st er as of January 1, 2012, all vessels must have an identification mark that can be used to differentiate between vessels in the event of search or rescue. This is the display of the registration number (the 8 characters on the navigation title). The internal identification mark allows any navigator in difficulty to give his identification by VHF to the rescue services. This is why it must be legible near the navigation station (chart table) or near the steering station, especially on motor boats. This mark also allows easy identification of vessels or wrecks by boarding them. The dimensions (size of the letters) of this marking are free.
External marking
The inscription of the boat registration number depends on the type of boat.
| Type of boat | Composition and location of the marking |
| Sailing ships | Name of ship and initials of the Registry at stern |
| Motor Vessels | Registration number on both sides of the hull or superstructure |
| Personal Watercraft (PWC) | Registration number visible while sailing on both sides of the hull |
| Annexes | AXIS + marks of the carrier vessel |
| Human-powered craft | Registration number on both sides of the hull (registration not mandatory for navigation within 2 miles of a shelter) |
Font size
Sailboat :
- A sailboat less than 7 metres in length is not required to carry an external identification mark.
- Sailboats of 7 metres and over must bear, on the outside: their name and the name or initials of the registration service visible (home port).
Motorboat :
- Less than 7 metres: Free dimensions without being less than 4 cm high, 1.5 cm wide reserved for each character Line thickness: 0.5 cm min.
- Between 7 and 12 metres: Free dimensions not less than 7 cm high, 3 cm wide reserved for each character Line thickness: 0.8 cm min.
- More than 12 metres: Free dimensions without being less than 12 cm high, 5 cm wide reserved for each character Line thickness: 1.5 cm min.
Motorised watercraft :
- Free dimensions without being less than 4 cm high and 1.5 cm wide reserved for each character Line thickness: 0.5 cm min.
Craft powered primarily or exclusively by human energy:
- Free dimensions without being less than 4 cm high and 1.5 cm wide reserved for each character Line thickness: 0.5 cm min.
