An anchor is a device that is used to stop a ship or boat from drifting away. Anchors are made from heavy metal, and are hooked so they catch onto the seabed. They are attached to the ship by a long chain or rope, and are let down when the ship needs to be still, and lifted up when the ship needs to move again.
A catamaran is a type of boat that has two hulls. The hulls are connected somehow, ranging from a simple connection with thin rods to the bulk of the boat forming the bridge.
Catamarans may be either sail or motor powered, and can be any size from tiny sailboats to quite large ships.