Kon-Tiki Expedition (1947): Metadata

There is no infomation in the Met Log on the nature or use of the weather instruments, but we can glean some information from the published accounts of the voyage:

It is likely there are more weather observations than those in the Met Log: Barograph traces, more precise wind speeds, and more than two observations/day (from descriptions in Heyerdahl’s The Kon-Tiki Expedition). The same source states that observations were sent, by radio, to the Weather Bureau in Washington twice a day - the Met Log might well contain these radioed observations. (It’s not clear what the Weather Bureau did with the observations they received).

Air Temperature

I can find no indication of how the air temperature observations were made. I found no sign of a stevenson-type screen in any published photograph or illustration.

Sea Temperature

I can find no indication of how the sea temperature observations were made. Kon-Tiki is almost unique in that it would have been easy just to stick a thermometer into the surrounding ocean, and this may well have been done.

Air Pressure

I can find no mention of a barometer in any of the voyage accounts. But managing a mercury barometer on the raft would not have been easy, and an illustration in Hesselberg’s Kon-Tiki and I shows an instrument which could be a barograph. So I’m assuming the pressures are from an aneroid barometer.

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Section of an illustration from Kon-Tiki and I, by Erik Hesselberg, copyright Allen and Unwin Ltd.

Wind

Wind observations were made using a hand-held anemometer - see illustration in Hesselberg’s Kon-Tiki and I, also there’s a photo in Heyerdahl’s The Kon-Tiki Expedition.

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Section of an illustration from Kon-Tiki and I, by Erik Hesselberg, copyright Allen and Unwin Ltd.

Heyerdahl’s book also indicates that observations were made at the masthead (at a guess, 6m above sea-level?), and several times a day.

It’s notable that the wind observations in the Met Log are in Beaufort Force - possibly they were transformed for radio transmission.