Lifebuoy

In the United States, Coast Guard approved lifebuoys are considered Type IV personal flotation devices.

Leonardo da Vinci sketched a concept for a safety wheel, as well as for buoyant shoes and balancing sticks for walking on water.

[7] In the book Architectura naval antigua y moderna (1752) by Juan José Navarro, 1st Marquess of Victoria, two plates show "circular lifebuoys" and another plate includes a drawing of "a lifebuoy made of cork", called "salvenos".

The lifebuoy was attached to a rope on one side and to the poop of the ship on the other, so that it may be deployed in case anyone should fall into the sea.

[9] It was made of "800 old tavern corks" affixed to a band, "covered in canvass, and painted in oil, so as to render it waterproof.