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River Science: Wind Speed

Of all the weather phenomena our students study, the speed and direction of the wind have the most immediate effects on our ship. Not surprising, considered that the Half Moon is a sailing vessel! In 1609, Hudson's progress along the narrow river was often at the mercy of favorable winds. On this voyage, we are monitoring wind speed as a component of our Deck Log and AMVER SEAS reports.

We use hand-held anemometers to accurately measure the wind's speed. As the wind blows through and spins an anemometer's fan, the electronic instrument records the wind's highest and average speeds.

When at sea, it's possible to measure wind speed with reasonable accuracy even without the use of precise instruments. The Beaufort scale estimates wind speed by categorizing observable water conditions into 12 "sea states," ranging from 0 (dead calm) to 12 (hurricane). The small waves and frequent "white horses" we see in the photo here (from Gravesend Bay) places us in state 4 (moderate winds), which means the average wind speed is likely between 11-16 knots.

When we study wind speed in depth for research projects, we often simultaneously compare wind speeds on deck and at the mast tops. Our findings during these experiments indicate that the wind is consistently stronger at higher elevations.

This would have come as no surprise to the shipwrights who constructed the original Half Moon in 1608; after all, top sails are desined specifically to harness those higher, more powerful gusts.
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