Thor Heyerdahl is wowing 'em in Boston with stories he began telling in 1947: of drifting in the balsa-log raft Kon-Tiki from Peru to Polynesia; of the papyrus boats Ra I and II he took across the Atlantic in 1969-70; and of the reed ship Tigris he sailed through the Persian Gulf and around the Arabian Sea in 1979. Suddenly the world's best-known adventurer throws his audience a curve that has them pinching themselves to see if they're dreaming.
''I think really that what has made me succeed in these voyages is that I started as a complete ignorant when it comes to both the ocean and navigation. Because contrary to what people believe, I am not a sailor, I am not a navigator at all.''
Not as heartrending as hearing the truth about the tooth fairy or the Wizard of Oz, perhaps. But that tidbit and the guffaws of disbelief it gets speak volumes about the man, his famous life, and the world of misconceptions still entertained about him.
''I was just telling the man at my table,'' he continues, ''that I didn't learn to swim until I was 22 and fell into a river in Tahiti.''
In the first place, this select gathering at the Museum of Science must learn he's not kidding. This is something his world audience learned 35 years ago when he and his crew set sail for 101 days in a boat made of a material (balsa) ostensibly proved to last for two weeks on the water.
In the second place, the learning-to-swim story, besides reflecting Dr. Heyerdahl's blatant honesty, became a metaphor for his life. His four voyages each represented a courageous plunge into the unknown, bold steps in the face of firmly held scientific assumptions. Having spent four decades popping those scientific bubbles, tonight he's popping them about himself.
''People think, 'My gosh, he is brave to go into a storm with a raft type of vessel.' But we know that we can take it because the waves come on board, maybe we get wet, but they're gone, straight through the bottom and out again like they do if you eat soup with a fork. A raft, you don't even have to bail.'' The point is, says Heyerdahl, ''that on vessels of these kinds, you don't have to be either a swimmer or a sailor. As a matter of fact, I made a point on these expeditions: On all of them I've had only one who you could call a real professional seaman.''
Ironically, all these disclaimers leave those in awe of his accomplishments more in awe of the man. Adventurer? No. Hero? No. Explorer? Maybe. But primarily an anthropologist, he will tell you.
''I have proved that all the ancient pre-European civilizations could have intercommunicated across oceans with the primitive vessels at their disposal,'' Dr. Heyerdahl said at the end of his last expedition in 1979. ''I feel that the burden of proof now rests with those who claim the oceans were necessarily a factor in isolating civilizations.''
Having spent a lifetime making this point, the 68-year-old Heyerdahl now reinforces his theories based on work in Colla Micheri, a medieval Italian village on the northern Mediterranean coast. He is soon to publish his life's crowning work, which will tie information from his four main voyages with his most recent experiments. Those involve six-foot-long reed models he operates by remote control on lakes in West Germany, Iraq, Chad, and South America.
He has welcomed the chance this night to interrupt those activities to receive yet another award. That means being dinner-guest of honor with cognoscenti of Boston's science community. It also means accepting a gold medal (the Bradford Washburn Award for Outstanding Contribution to Public Understanding of Science), $5,000, and the obligation to tell of his adventures. For over an hour, Dr. Heyerdahl reflected loquaciously on his lifework, exploding what he calls those ''crazy notions'' people have about the sea, sailing, boats, navigation - and himself. In doing so, he elaborated on the themes that thread his lifetime of scientific discovery.
Myth No. 1: ''We have some very, very crazy ideas about where the ocean is dangerous and where it is safe. You can look into any respectable anthropological publication and you may find that it is possible to go from A to B because the primitive craft may hug the coast. If there is anything that is difficult, it is to hug the coast. On all my expeditions by primitive craft across the three main oceans, together with my crew, I can testify that the day we see land disappear, that's the day we can draw a deep breath and feel now we are off for a fine cruise.''
Silver-maned Dr. Heyerdahl speaks humbly, with an amiable Swedish lilt. His otherwise excellent English is spiced nonetheless with certain near-incomprehensibles (''no longer widows'' for ''no longer with us'') in the manner of the Muppets' Swedish chef. Tonight, unlike his habit on most of his voyages, he is clean-shaven.
''The main problem is the coastal area,'' says Heyerdahl. ''A, because that's where you can collide with the rocks and shallows; B, that's where the waves are twice or three times as tough, because you get the backwash, so you get the addition of currents and you get the choppy, crazy sea. You never know what you're up to.
''But once you're out in the middle of the ocean, you get long, rolling swells and there is nothing to worry about. It's exactly the opposite of what people would think.''
His 4,300-mile Kon-Tiki voyage (named for a legendary pre-Inca sun king) bore this out. With five others, Dr. Heyerdahl left Callao in Peru and arrived on the Raroia atoll in the Tuamotu Archipelago. The most famous of his voyages supported his theory that it was perfectly possible for Peruvian aborigines to have peopled those Polynesian islands.
Myth No. 2: ''We think a caravel [a type of ship] like in the days of Columbus must be much safer than the raft because it's high up and much bigger.''
Yet there is much more danger in the latter, he says, because the higher the boat stands out of the water, the more its danger of capsizing. ''You know that I would be dead scared of being on a caravel in a hurricane or bad weather, and I would be 100 percent safe on a raft,'' he says.
Heyerdahl puts himself firmly into neither group of scientists who, he says, have for decades carried two erroneous notions about the sea: ''One group - the isolationists - has considered the ocean a vast, bottomless abyss that you cannot get across because you cannot walk on the bottom.
''Then you have the opposite group. They consider the ocean like a sort of a frozen skating rink, where you can just play in any direction as you please. Neither of these is what the ocean is like.''
Heyerdahl says the ocean is a vast network of highways, ''invisible marine rivers'' that form paths between continents. The largest of these is the Humboldt Current, flowing west through the Pacific off of South America. ''If you have a vessel that doesn't move at all, you can just sit there and you get a free ride, just like you get on the Amazon River, to the other end.''
The Humboldt Current flows just as clearly as the Amazon overland, he says - green water through ''banks'' of blue water. The color difference is due to the differing temperatures and the differing types of plants that grow in each.
He says that without a knowledge of these currents, a navigator will have no idea how long it will take him to reach his destination. ''The distance depends on the direction. Because if you go one way, you may have to go much, much further - upriver, in a sense. The other direction may double your speed. This is something you don't realize, looking at the map or a globe before you get out in the ocean and see what the water is like.''
The distance between Safi, Morocco, and his destination for the 50-foot Ra I in Barbados, West Indies, was 3,270 miles. This time he was attempting to demonstrate there could have been communication between Africa and pre-Columbian America, which could account for the transfer of pyramid-building techniques. The expedition only made it 2,700 of those miles. Interrupting the voyage one week short of Barbados because of broken rudder oars, Heyerdahl repeated the experiment successfully 10 months later with the smaller (40-foot) Ra II.
Myth No. 3: The longer the boat, the better. ''I have found from my own raft expeditions that if we make our boat too long, we get more trouble because we can't fit in between the waves. In bigger boats, both the bow and the stern can be lifted up by two different waves, with the risk of breaking midship. Or if you are not lifted up, maybe your stern will cut into the waves and you will get them over you while the bow is lifted up, and vice versa.''
Dr. Heyerdahl had his own ''small is beautiful'' theory long before it became a catchall phrase: ''If you have a small boat, it's like a seed or a bird - it will just bob up and down in between the waves and you don't even take water on the raft.''Dr. Heyerdahl points out that most of the craftsmen who knew how to build primitive-style boats are now gone. Scientists have had to rely mostly on what they find from studying pictures - whether prehistoric rock carvings, relief carvings from Mesopotamia and Egypt, or some fresco paintings - to build replicas of ancient craft.
''You couldn't go to somebody and ask, 'How shall I do it exactly?' - except in certain areas where I've been visiting,'' he says. Those areas include primarily Chad in Central Africa and the Lake Titicaca region in Bolivia, South America.
''Actually, what I've learned I basically learned from those Aymara, Uru, and Quechua Indians in South America, because it's the only place in the world where these techniques are still in use.''
The secrets of his boats, he says, are that everything must be buoyant as well as resilient - no metal, no chain, no wire. ''Everything is flexible so it moves with the waves, then the wind and the sea cannot get at you.''
Heyerdahl said that it was his first Ra expedition that led to an invaluable tip about keeping papyrus and other reed boats afloat longer.
''We had caught the trade winds and the Canary current with good speed in the direction of America. But after a while we noticed that the all-important stern that should keep us dry from the waves started sagging down from water absorption. It became more and more like a submarine.''
He says the crew had a hard time keeping the boat together. The waves burst on board, crashing into the bamboo cabin until the ropes holding it stationary were severed. ''It was encouraging to see that the reeds were still floating, but they weren't floating together with us,'' he says. As they moved closer and closer to America, the sides of the vessel settled so close to the water that all the crew brushed their teeth in the ocean. ''And you will hardly believe it, but barnacles grew on top of decks. And we had chicken and ducks, and the ducks were happier and happier and the chickens weren't.''
After ending the mission one week short of their destination, Heyerdahl's quickened resolve led to the discovery that made his final expedition, the Tigris, the longest in duration and most successful: five months, 4,200 miles.
''The secret of why my last ship (Tigris) floated so long was that we had done what the marsh Arabs, living on floating reed islands in the marshes of Iraq, had told us. This was what no other people knew, including scientists: that you must cut the reeds in August to keep them afloat for a long time. We had been cutting ours in Ethiopia, the source of the Nile, in the month of December each time.''
The difference, says Heyerdahl, is that in August there is some sap in the reeds that is water-repellent. ''The water will not enter the reeds as readily, '' he says, ''and the boat will stay afloat longer.''
With Arab workers and reed-boat builders from Bolivia, Heyerdahl built a ship modeled from ancient Sumerian drawings. The ship was made of berdi reed, harvested where he Tigris and Euphrates join to flow into the Persian Gulf. He and crew of 11 dodged supertankers in the busy shipping lanes there, made it to the Indus Valley of Pakistan, then to the Horn of Africa, and back to the entrance of the Red Sea.
The Tigris was 60 feet from stern to bow and carried enough drinking water and food for six months. By the time the voyage ended five months later, the ship had taken on tons of water - yet had still a good six months' more seaworthiness, he says.
That is the boat Heyerdahl and crew ignited at the port of Djibouti, however, in an international gesture of protest against the Ethiopian-Somali war in the Persian Gulf.
''We sailed toward Somalia and we got the message that there was war there, that we should go to the other side of the Gulf of Oman. When we got there, southern Yemen was fighting with Iran, so we stayed away from that side, too. We kept in the middle and learned there was war between Eritrea and Ethiopia, so we couldn't go there, either.''
Finally, he says, at the entrance of the Red Sea in Djibouti, that small nation's president sent them a welcome message, and they went ashore. They felt they had proved their point - sailing between two of the earliest civilizations (Mesopotamia and the Indus Valley). So, unable to get the boat out of port again , or salvage it before it rotted in the harbor's polluted waters, they sent it up in flames of protest.
''We did it, sails up, took the UN flag down, and sent an appeal to [then-UN] Secretary-General Waldheim telling him that 11 men from 11 nations had lived together in peace and cooperation. And that it was for us really sad to come back to civilization and see what modern man is doing in the part of the world where civilization started.
''It was perhaps the saddest moment any of us had had, but this is the way the Vikings did it.''
With that voyage, Dr. Heyerdahl, in his words, ''tied together with prehistoric vessels'' Asia and Africa. His Kon-Tiki mission tied South America to Polynesia, and his two Ra expeditions tied Africa to America. The conclusion: compelling evidence that men were crossing oceans spreading their cultures thousands of years before Columbus.
There is one other statement he likes to make on his missions - that men of different cultures, languages, and backgrounds can live harmoniously for months at sea in close quarters under adverse circumstances.
On his last three voyages he took Norman Baker from the United States as navigator and Yuri Senkevitch from the Soviet Union as the medical doctor. ''And just to have a political contrast, I've had one Jew and one Arab, black and white and yellow, Mexican and Norwegian. Making the contrast in one of the most rewarding parts of the trip. As long as you're not fanatic you can get a lot of fun out of it and you can learn a lot about yourself and the world.
Shortly after the Tigris voyage, Dr. Heyerdahl ended his exotic voyages of discovery saying, ''At the moment, there are a few unanswered questions in my mind that would be answered by another voyage.'' Yet in the three years since that mission, Heyerdahl has had a team of scientists at the University of Bombay conducting boat waterproofing experiments. He also sends students up and down the west coast of India, from Sri Lanka all the way uo to the borders of Pakistan. They interview all the old fishermen in all the fishing villages where boats are still built. Their questions, too, are about what is used to waterproof their vessels.
It is this painstaking research in between his voyages that had led to their great success, he says. ''I'm considered a great adventurer because each time I step on these vessels of mine, people think that's all I do. I enjoy adventure. I wouldn't avoid it if it's involved in my research. But I would never look for adventure; that's not my purpose.
''But if you look at the decades I've been working at this, the voyages are only months long with 10-year intervals. I'm doing this archaeological work all the time. This doesn't make headlines in the paper.''