Lionel Casson, an expert in ancient ships, explains what shipbuilders in Roman times did after caulking the seams in their vessels’ planking. It was common for them “to smear the seams or even the whole exterior hull with pitch [bitumen] or pitch and wax, and to spread a layer of pitch on the interior.” Long before the Romans, the ancient Akkadians and Babylonians also used bitumen to waterproof their vessels.

The Hebrew Scriptures make reference to a similar technique at Genesis 6:14. The Hebrew word here translated “tar” evidently refers to bitumen, a naturally occurring petroleum substance.

Natural bitumen comes in two forms​—liquid and solid. Ancient shipbuilders used the liquid form; they would apply it directly to their vessels. Once applied, the liquid bitumen dried and hardened to form a waterproof coating.

Bitumen was plentiful in Bible lands. The Valley of Siddim, in the Dead Sea area, “was full of bitumen pits.”​—Genesis 14:10.

Fish has long been an important food item. Before beginning to travel with Jesus, some of his apostles were fishermen on the Sea of Galilee. (Matthew 4:18-22) At least a part of the catches taken there were processed in “factories” located nearby.

The technique for fish preservation likely used in ancient Galilee is still used in some places. The fish are first gutted and washed in water. The book Studies in Ancient Technology describes the steps that follow: “Coarse salt is then rubbed into the gills, mouth and scales. Alternate layers of salt and fish are covered by dry matting. After standing from 3-5 days the pile is turned over to stand for a similar period. During this drying the body fluids drain away and salt solution penetrates the fish. After this drying they are firm and hard.”

It is not known how long fish would keep when preserved in this manner. However, the fact that the ancient Egyptians exported cured fish to Syria indicates that the methods used worked reasonably well.