For inland waterway shipping, a blue sign with a 360 degree white flashing light is a day and night signal with which passing ships can communicate, so that people can meet each other starboard to starboard instead of the usual port to port side.

The sign must be easily visible from the front and the back.
The colour of the sign is bright blue (RAL 5017) and the sign has a white edge of at least 5 cm.
Any frame and/or bars, as well as the lamp housing, must have a dark colour.
The dimensions must guarantee good visibility; this is satisfied if the length and the width of the sign are at least 1 metre.

Voltage: 24 volt
Amperage: 1.5 A
Materials: plate : aluminium
: frame : aluminium
: rotating shaft : stainless steel
: cylinder : nickel-plated steel
: mounting pipe : stainless steel