After the Ra II expedition Thor Heyerdahl became very interested in the much disputed question of whether or not there had originally been communication between the three original civilisations in Mesopotamia, Egypt and the Indus Valley. In all three of these culturally related areas prehistoric artists have left behind depictions of the same sort of reed boats that he himself had used to cross the Atlantic Ocean.
One of the main problems during the Ra and Ra II voyages was that water absorption made the reed boats float very low in the water, covering their decks in water in the last few weeks. Heyerdahl learned from the Marsh Arabs, who live in the former Sumerian region of Iraq, that if the reeds were cut in August they would retain their buoyancy. Heyerdahl decided to try this and at the same time experiment with navigating a reed boat.
In 1977, Heyerdahl built his largest reed boat 18 metres long. The reed vessel was named Tigris after the river in which it was launched. Tigris was built under the leadership of the same South American Indians who had built Ra II. Once again Heyerdahl sailed under the UN flag and with an international crew of 11 men.
The Tigris voyage lasted for 6,800 km. The boat first sailed down Shatt-el-Arab from Iraq to the Persian Gulf and out into the Indian Ocean. Thereafter the voyage continued on via Muscat in Oman to the Indus Valley in Pakistan before it finally left Asia and sailed over the Indian Ocean to Africa.
The five month long voyage ended in Djibouti at the entrance to the Red Sea. Surrounded by war on all sides the members of the expedition decided in April 1978 to burn the boat. At the same time they sent out a unanimous appeal to the UN to stop the delivery of weapons to developing countries in this part of the world, which had laid the foundations for our own civilisation.
Unlike Kon-Tiki and the two Ra boats, Tigris sailed to pre-planned harbours regardless of the wind and ocean currents. Once again Heyerdahl had shown that the ocean was a link and not a barrier between different cultures, and that it linked together the Sumerian region in the Persian Gulf with the Indus Valley and the ancient Egyptian seafaring region of the Red Sea.
A popular book and TV film resulted from the expedition
Boats constructed from different species of reed have been built and used along the coast of Peru and on the inland lakes of Tana in Central Africa and Titicaca in South America up to modern times. In Europe, poor fishermen in Ireland still used boats that had wooden frames and bundles of reed for buoyancy in the 1930s. Small reed boats have also been used by fishermen from Sardinia.
No one has ever really established just how long mankind has been using reed boats. Large reed boats with space for people, animals and cargo were being built in Mesopotamia more than 5,000 years ago. These are depicted on small cylindrical seals. Similar boats are depicted on seals from the Indus Valley and on paintings in Egyptian tombs from as early as 2500 BC.
Thor Heyerdahl had proved the seaworthiness of reed boats with his two Ra expeditions. Tigris could have stayed afloat for many more months. Calculations done by Thor Heyerdahl clearly show that reed vessels of this size were capable of carrying 30-50 tons of cargo and could therefore have been used as trade vessels