When you have one of these – The USS Ronald Reagan is a Nimitz-class aircraft carrier. It's almost 1,100 feet long, with a flight deck 252 feet wide and it displaces 97,000 tons.
And if it's here – The aircraft carrier USS Ronald Reagan leads a formation of 42 ships and submarines from 15 international partner nations during Rim of the Pacific (RIMPAC) 2014.
You need to have these – Life preservers. Seaman Rebecca Stephens, from Denver, cuts tape to apply to the batteries of a Firefly distress marker light attached to a life preserver in the hangar bay USS Ronald Reagan on August 3.
But you need to have two different kinds, one for crews on the flight deck – Sailors on the flight deck catch their breath alongside an F/A-18E Super Hornet during a break in flight operations aboard the USS Ronald Reagan.
And one for everybody else aboard – Capt. Buzz Donnelly, commanding officer of the USS Ronald Reagan addresses the crew during an all-hands call in July 2016. A Nimitz-class aircraft carrier like the USS Ronald Reagan carries about 5,700 sailors and air crew.
And you need to count them all and make sure they work – On August 3, 2016, Reagan crew prepare for an inspection of life preservers in the hangar bay of the USS Ronald Reagan. In the foreground, sailors work on life preservers for the flight deck crew. There are about 700 of those aboard. In the rear are general life jackets, there are about 7,000 of those.
The kind worn by flight deck crews are called MK-1s – The MK-1s are auto-inflatable. Sailors wear them on the flight deck during flight operations to help make them more visible and to help them survive and aid their rescue if they fall overboard.
Some crew wear "kapoks" – About 70 of these "kapok" life preservers are used in special situations. A boat crew prepares to lower into the water on the starboard side of the aircraft carrier USS Ronald Reagan.
The kind worn by everyone else are called "rubber duckies" – The "rubber duckies" are kept in fanny packs and pulled out and put over the head in an emergency. Here, crew run a 5K on the deck of the USS Ronald Reagan.
Which come in handy if this happens! – *No sailors, ships or rubber ducks were harmed in the making of this gallery.