What may seem so simple, actually has a lot more to it. This is how ship anchors work.
Everyone knows the purpose of a ship's anchor, right? That of making the ship come to a complete stop and prevent it from drifting away from a specific spot. But here is what you didn't know.
Most people assume that the anchor hook itself is what gets wedged into the ocean floor to help stop the ship. But, in reality, the only purpose of that is to keep the anchor's chain in a certain position. It's the weight of the chain that does all the work. And average anchor weighs in at around 15 tonnes, which is a hell of a lot, but nothing in comparison to the 80-tonne chain!
When the ship is ready to haul up the anchor, the ship navigates towards the anchor and reels in the chain first, when the ship is directly above the anchor, it then is at the right angle to be unwedged from the sea bed and up it comes into the ships haul.
Once the anchor is back in, an anchor washing system is engaged. You'll see a significant amount of water pouring out of the anchor slot in the bow of the ship which is used to wash away any see floor debris.
Take a look at the video below by YouTube channel, Casual Navigation, on How A Ships Anchor Works - Anchoring Massive Ships.