The ancient Greeks and Romans had a strong naval tradition and relied heavily on their fleets for trade, transportation, and warfare. To maintain the efficiency of their ships and prevent biofouling, they used a variety of methods.
One method was to coat the bottom of the ships with pitch. Pitch, also known as tar, is a sticky substance made from the resin of pine trees. The Greeks and Romans would heat the pitch to make it more liquid, and then apply it to the bottom of the ship. The sticky nature of the pitch made it difficult for barnacles and other marine organisms to attach to the hull.
Another method the ancient Greeks and Romans used to prevent biofouling was to cover the bottom of the ships with copper sheets. Copper is toxic to many marine organisms, and it also prevented the attachment of barnacles and other organisms that would grow on the ship’s hull. They also would use copper nails to fasten the planks of the ships together which also have a protective effect.
Additionally, they would occasionally haul the ships out of the water and scrape off any barnacles or other organisms that had attached to the hull. They would do this using metal scrapers or even simple tools such as shells and stones. This process would make sure that the ship is in perfect condition before it could go out to sea again.
Lastly, it is also believed that they might have used herbal and chemical methods to prevent biofouling. for example, they used a mixture of oil and sand as an abrasive to scrub barnacles and other organisms off the hull, or even sometimes use wine which was believed to contain tannins that inhibit the growth of marine organisms.
It’s important to note that it was not uncommon for ships to spend long periods of time in port and not at sea, and as such, ancient fleets may not have been able to prevent biofouling on long voyages. However, the methods they used were quite effective in keeping their fleet efficient and preventing the attachment of biofouling.