Answer 1
A buoy is anything that's used to provide flotation (buoyancy) to another object.
Some buoys are tethered and allow navigational aids to float in place, others (sonobuoys, radiobuoys) are free-floating or tethered to objects suspended in the water column (like fishing nets).
More examples are listed below, all of them have the common purpose of providing buoyancy.
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Answer 2
A buoy is a floating object in the water that is anchored to the bottom of the body of water.
Bouys have two main purposes.
The primary purpose is a navigation aid. They mark channels into harbors and deep water channels in rivers as well as mark off hazards and specific areas. "Red, Right, Returning" is a phrase that sailors use to remember that the red bouys should be on the starboard side of the channel and the green ones on the left when coming into the harbor. They may or may not have lights and/or sound devices (a bell being common) on them.
There is also the anchor or mooring bouy that is found in harbors and lakes so that the owner of the bouy's boat can attach a rope for mooring purposes.
An anchor buoy is a small buoy attached to an anchor by a light line and used to indicate the position of an anchor.
Buoy is a homophone for boy. A buoy is a floating object used to mark a location in a body of water.
The word is buoy.
Achoragae area
a horizontally marked red and black buoy used to mark the division of sea lanes when moving inward from the sea.
buoy
White buoy with blue
blue stripe
This is a mooring buoy or mooring ball. They are used in either a public or private capacity to moor your vessel to. In a way it acts as an anchor for your vessel. Instead of dropping an anchor though, you simply pull up to the buoy and slip on a line (rope) and make fast. It also the ONLY acceptable buoy you may do this to.
Buoy can be a verb. Her presence would always buoy my spirits.
white buoy with a horizontal blue stripe
mooring buoy