Why Poisonous Layer Applied on the bottom of ship

Water ship is often used for long distance trips or transportation. During this time the ship stays in water for several days.

Do you know why the layer of poison is offered on the bottom of the water ship i.e. its bottom? What is the use of this layer?

Actually, many sea creatures stick to the floor of the ship due to long stay in water. This makes the bottom part heavy and starts deteriorating.

To prevent the floor of the ship from malfunction, the layer of cuprus oxide is offered in it. This protects sea vessels from plants, animals and algae.

The special thing is that whenever the ship completes the journey and returns, then this layer is mounted. This keeps the ship safe for a long time