Debbie Stringham, July 8, 2005

NOAA Teacher at Sea
Debbie Stringham
Onboard NOAA Ship Fairweather
July 5 – 15, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: July 8, 2005

Survey launch
Survey launch

Weather Data 

Location: in transit
Latitude: 59 02.8’ N
Longitude: 152 33.6’ W
Visibility: 10 nm.
True Wind Speed: 10 kts.
True Wind Direction: 235
Sea Wave Height: 1-2 ft.
Swell Wave Height: 2-3 ft.
Sea Water Temperature: 12.7 C
Sea Level Pressure: 1000.5
Sky Description: Partly Cloudy
Dry Bulb Temperature: 15.9 C
Wet Bulb Temperature: 13.9 C

Science and Technology Log 

I Woke up early again to stand watch on the bridge, but was informed by the XO that I would be out on a launch at 0800. He suggested I go back to bed and get ready for the day since it would probably be a long one. At 0800, the crew met on the fantail (stern of the ship) to discuss safety precautions, then the vessels were lowered over the side of the ship, where all of the equipment and crew were loaded, then placed in the water. Normally, the boat would head to a section of the coast, in this case the Shumigan Islands, to begin sound velocity casts, but our boat was having generator and engine troubles so we had to head back to the ship shortly after we departed. The captain, or commanding officer, gave me a book titled, How to Read a Nautical Chart, and briefly explained why ships travel the “great circle”. I read sections of the book and learned about Gnomonic versus Mercator projections.

On a Mercator projection, where latitudes and longitudes cross each other at right angles, a straight line is not the fastest course. This type of projection is best used for coastal sailing and is where the “great circle” comes in to play as the shortest route.

On the other hand, the Gnomonic projection is best used for open passage sailing. The latitude lines are seen as curved and the longitude lines are straight. On this type of projection the shortest distance is a straight line.

Question of the Day 

Why do sailors refer to the sides of their boats as port side and starboard side?

Answer from Previous Day 

Hydrography is the science that deals with the measurement and description of the physical features of bodies of water and their littoral land areas. Its primary use is for nautical charting, but it is also important for port and harbor maintenance, coastal engineering, coastal zone management, and offshore resource development.

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