Lifeline — a means to assist someone who is drowning. It is a float made of solid floating material in the form of a torus ("bagel") or horseshoe. It is painted in a bright, noticeable color-bright orange or red, perhaps with a few white stripes. On a circle the Leer is fixed.
In 1915, sir, the chief naval staff of the Royal Navy of the United Kingdom was invited to Doyle for consultations. And soon the Navy in the list of mandatory equipment were introduced lifebuoys.