Yachtmaster Ocean Theory Course

To learn the art of Astro Navigation and the key concepts of planning Ocean Voyages.  The earth and the celestial sphere; Practical guide to use and care of sextant at sea; Meridian altitudes; Sun, star and other sights, ocean passage planning

This is a 6 day course run by an RYA Yachtmaster Ocean Instructor.

Candidates should have navigation, passage planning and meteorology knowledge up to RYA Yachtmaster Offshore Shorebased level and some practical experience of putting this knowledge into practice.

The course covers celestial navigation, worldwide meteorology and passage planning.

The majority of the course is spent developing an understanding of how to use the sextant, how to apply corrections and how to then calculate your position using the sun, moon, stars and planets.

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

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

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

Measurement of time

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

Meridian altitudes

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

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

Compass checking

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

Satellite Navigation Systems

  • Principles and limitations of use of all systems

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


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

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

Passage making

  • Navigational routine
  • Watchkeeping
  • Crew management


  • Satellite and terrestrial systems
  • Weather information

This is an advanced navigation course aimed at Blue Water sailors, anyone crossing the Atlantic (or other) Ocean, Super Yacht Deck Officers and Commercial Yacht Skippers planning on operating more than 150NM from a safe haven.

Candidates should have navigation, passage planning and meteorology knowledge up to RYA Yachtmaster Offshore Shorebased level and some practical experience of putting this knowledge into practice.

The RYA/MCA Ocean Yachtmaster Shorebased Course is also a stepping stone to the RYA/MCA Ocean Yachtmaster Certificate of Competence and a mandatory certificate for the MCA Master 200/OOW 500 (unrestricted) and Chief Mate (less than 3000 tonnes) qualifications.

For leisure sailors this is the most advanced course in the RYA scheme and will give you more knowledge to sail safely to some of the worlds most stunning blue water destinations.

For commercial sailors who already hold the Yachtmaster Offshore Certificate of Competence and/or Master 200 (restricted) CoC, becoming a Yachtmaster Ocean CoC, “removes the 150 mile from a safe haven” restriction you currently have. The RYA/MCA Yachtmaster Ocean shorebased course is a step towards the full RYA/MCA Ocean Yachtmaster.

9am-5:30 pm each day with approximately 45 mins / 1 hour for lunch

Minimum Duration: 6 days

16 years old.

This course operates with a maximum of 12 students per instructor although in practice we usually operate with much smaller classes.

Course Price £500

Book for 2 people or more and save 10% off the total price

Course Pack includes:

  • Exercises and Course information,
  • Shorebased Notes,
  • Sight Reduction Tables and
  • Nautical Almanac Extracts.

For the classroom course, we provide all the tables, sextants and other tools for this course.

You will have access to a Sextant during the course but if you do have your own you are very welcome to bring it along to try it out and get to grips with it.