The Plimsoll mark on a boat is a line that delineates how low on the water a boat should be at full cargo capacity. Samuel Plimsoll, the man behind this concept was an advocate for sailors and safety aboard all vessels. Plimsoll wrote a book titled "Our Seamen" which contained details about the hundreds of sailors who had died at sea due to inadequate safety precautions. Plimsoll distributed his book to the members of the House of Commons in an effort to persuade them to pass the Merchant Shipping Act. The Act passed in 1871 and the Plimsoll line become a safety standard.