An anchor is not "thrown", but dropped, the command is: "drop anchor". There are many different shapes, sizes and weights of anchors available.
Depending on the type and texture of the anchoring ground, different anchors are suitable in some situations, while others are not:
• Mud: Was formerly entirely unsuitable for anchorage (no adhesion for stock anchors)
• Silt: Has very bad ashesion and was formerly unsuitable for prolonged anchoring (stock anchors sank too deeply)
• Gravel and stones: Considered difficult to ideal, depending on the particle size of the stones and the texture of the anchor
• Large stones: Problematic due to the difficulty of wedging the anchor successfully
• Clay: Good anchorage, since it's composed of uniformly sized particles and it's very porous
• Sand: Provides the best anchorage
The texture of the sea floor is given on marine charts. In cruising guidebooks, suitable anchorages are described together with indications of the weather conditions (wind directions) that are suitable for mooring.