Activity Description
"HYDRO BOXES." Various unknown objects are fixed on the bottom of each box
which is covered with a mesh screen. Students will probe through the mesh with
small sticks trying to discover the mysteries that lie beneath.
Major Concepts Addressed in the Activity
The location of shipwrecks and other obstructions are determined by
conducting Hydrographic Surveys.
Depth measurements techniques have changed over the years. Early Hydrographers
simply dropped a long rope line with a lead weight on the end over the side and
took measurements when it hit bottom. Today we use sonar and measure the time it
takes for the sound to echo off the sea floor. We then translate that into depth.
We use both single beam which gives us a narrow measurement of the depth as the ship
passes over the sea floor, and multibeam which gives us a wider picture.
Activity Questions
- Why might you not just want to jump off the diving board or pier into
the water on a hot day?
- Is it important for a ship's captain to know what's under the surface
of the water?
- How do you measure the ocean depths?
- Do you think there is "stuff" on the ocean bottom that hasn't been
discovered?
Acvitity Description
"MAKING A CHART." Students will modify a nautical chart on a computer
screen, renaming or moving features and print out a section of the chart to
take home with them.
Major Concepts Addressed in the Activity
The Office of Coast Survey is responsible for making nautical charts
showing ocean depths, obstructions, landmarks, place names, and everything
else that might help the captain or pilot of a boat or ship navigate safely
from one place to another and avoid unseen hazards.
Activity Questions
- How do we show ocean depths on a chart?
- What are some of the other water features we might want to show on a
chart?
- What are some of the land features?
- Why might a nautical chart need to be updated?
Products Made by the Kids
Students actually made and printed out a chart section using the computer.
Contact Jeff Stuart for information (301-713-2729 ext. 120) SSMC3, Station 7335.
