RYA Yachtmaster Ocean Theory  – Online

Client:      Advanced navigators wishing to take the final set- – Celestial Navigation

Dates:       Enrol anytime

Info:          On Line course plus lots of materials.

This course is provided by Navathome.com, a RYA training centre specializing on online training.  You will be their student.  You will be tutored/supported by an experienced RYA (Discovery Sailing) instructor working on behalf of Navathome.com.

This is a course in astro-navigation and worldwide meteorology which also reveals the mysteries of the sextant.  It assumes a knowledge of the subjects covered in the other shore based courses.

Duration 40 hours typical plus assessments

Material provided  RYA Student pack – notes, tables, almanac excerpts

Student:Instructor Ratio you and me


  1. 1. The earth and the celestial sphere
    • Definition of observer’s zenith and position of a heavenly body in terms of latitude, longitude, GHA and declination
    • Right angle relationships, latitude and co-lat, declination and polar distance
    • Relationship between GHA, longitude and LHA
    • Tabulation of declination in nautical almanac
    • Rate of increase of hour angle with time

    2. The PZX triangle

    • The tabulated components of the triangle, LHA, co-lat and polar distance
    • The calculable components, zenith distance and azimuth
    • Relationship between zenith distance and altitude
    • Introduction to the tabular method of solution in the Air Navigation Tables and the basic sight form
    • The use of calculators for the solution of the PZX triangle

    3. The sextant

    • Practical guide to the use and care of a sextant at sea
    • Conversion of sextant altitude to true altitude
    • Application of dip, index error and refraction
    • Correction of side error, perpendicularity, index error and collimation error

    4. Measurement of time

    • Definition of, and relationship between, UT, LMT, standard time and zone time
    • Rating of chronometers and watches

    5. Meridian altitudes

    • Forecasting time of meridian altitude
    • Reduction of meridian altitude sights

    6. Sun, star and other sights

    • Reduction and plotting of sun sights using Air Navigation Tables
    • Awareness of use of calculator for sight reduction
    • The plotting of sun-run-sun meridian altitude
    • Awareness of the reduction and plotting of sights obtained from stars, moon and planets

    7. Compass checking

    • Use of amplitude and azimuth tables systems and/or calculator

    8. Satellite Navigation Systems

    • Principles and limitations of use of all systems

    9. Great circle sailing

    • Comparison of rhumb lines and great circles
    • Vertices and composite tracks
    • The computation of a series of rhumb lines approximating to a great circle by use of gnomonic and Mercator projections

    10. Meteorology

    • General pressure distribution and prevailing winds over the oceans of the world
    • Tropical revolving storms, seasonal occurrence and forecasting by observation

    11. Passage planning

    • Publications available to assist with planning of long passages (routeing charts, ocean passages of the world and other publications)
    • Preparation for ocean passage including survival equipment, victualling, water and fuel management, chafe protection, spares and maintenance

    12. Passage making

    • Navigational routine
    • Watchkeeping
    • Crew management

    13. Communications

    • Satellite and terrestrial systems
    • Weather information

Advanced Navigation to Yachtmaster  Offshore or equivalent.

Once payment is made, we will set you up with a login and password on the site http://www.navathome.com

Your printed course material will be sent to you by Courier.