Wednesday, December 31, 2008

Ocean Navigation Introduction

Corrections to Sextant, Time, Sunrise, Sunset, Twilight, Moonrise, Moonset, Finding GHA and Declination, Assumed Position and Local Hour Angle, Computed Altitude and Azimuth, Amplitudes, Interpolation, Altitude Intercept, Using Position Plotting Sheets, Plotting Lines of Position (Sun, Moon, Stars) LAN, Running Fixes.

This was designed to help you prepare yourself to pass the Coast Guard exam on celestial navigation oceans, or if you are just interested in learning celestial navigation. I have written this with three ideas in mind.

1. Make it as short as possible.
2. Make it in plain arithmetic and keep it in a form that is easy.
3. Use only the materials that will be available in the exam room.

You do not need a sextant to work these problems or the ones on the exam. Learning to use the sextant is a personal skill that is acquired by practice. The Coast Guard test has 10 multiple choice questions with a passing score of 90%.

The Coast Guard exam questions may cover:
1. Sight Reduction (Sun, Star, Moon)
2. Star Fixes
3. Running Fixes
4. Latitude by Meridian Altitude
5. Latitude by Polaris
6. Time of Local Apparent Noon
7. Time of (Sunrise, Sunset, Twilight, Moonrise and Moonset)
8. Deviation or Gyro Error by Azimuth
9. Deviation or Gyro Error by Amplitude
10. Identification of Unknown Stars and Planets
11. How to Select Stars for a Fix
12. Correction of Sextant Altitude
13. ETA Problems
14. Time Tick Problems

I will give you step by step instructions for doing all these problems. You will need PUB 229 (15-30) and a reprint of the 1981 Nautical Almanac, Bowditch volume 2, plotting sheets, and a starfinder, dividers, parallel rules, triangles, and a calculator.

I will also show you how to do sailing problems:
1. Great Circle
2. Mercator
3. Parallel
4. Mid-Latitude

Also included in this site will be Terrestial exam questions:

1. Compass problems with Leeway
2. Finding Deviation or Gyro error on a Range
3. Compass deviation table problems
4. Computing the Visibility of a light
5. Distance off by two bearings
6. Finding a course to steer with a known set and drift
7. Radar plotting problems
8. Computing the height of the tide
9. Computing the velocity of the tidal current
10. Fuel consumption
11. Speed by RPM
12. Zone time calculations

This site will be updated and is under construction.