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.

 

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 instrumentation isn't available, sailors can also estimate wind speed using visual cues from the water's surface, including the height of waves at sea and the presence of whitecaps. (The whitecaps in the picture below were observed on a particularly breezy day.) The modern Beaufort Wind Force Scale classifies observed wind speeds into 12 categories, ranging from 0 (calm) to 12 (hurricane-force winds).

The Beaufort Wind Force Scale was first introduced in 1806, and served to standardize centuries of nautical traditions and individual rules of thumb that would have been second nature to sea captains like Henry Hudson in 1609.

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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