Learning Page

Shipcraft..River Science (page one) (page two). Presentations

We spent some of our voyage studying the river's currents, salinity, and animals. Some of the tools we used were also available to Henry Hudson's sailors, but others were more modern.

Salinity
The Hudson River is an estuary, which means that the saltwater from the Atlantic Ocean invades the river valley. The salinity at a given point on the river can change over the course of the year.Mr. Colley worked with Chris and Stephanie to study salinity and dissolved oxygen.

(Above) Using a refractometer to measure salinity. (left) A titration in process. Titration can be used to measure salinity or dissolved oxygen. (below) Comparing results obtained by the two methods.

 

Water Clarity
Clarity of the water can affect the animals and plants of the river. For example, more turbidity means that less sunlight reaches below the surface. Studying water clarity requires stepping onto the side of the ship to lower the Secchi Disc into the water. Use of the safety harness is required.

This is the Secchi Disc, which is used to measure water clarity. The student measures the depth of the disc when it is no longer visible.

Current Speed
This is important both to the animals in the river and the sailors on it!

(below) Chris would toss this wood chip into the water, and time its passage between two fixed points on the ship. He could then calculate the speed (of either the current flowing by the ship, or the ship's speed through the water).

Mr. Linehan works with Keionna on her study of current speed.