Yachtmaster Offshore Standard: Plot Release and Audit Board

The RYA Yachtmaster Offshore exam is a practical assessment of skippering, navigation, seamanship and safety awareness. Plotting instruments are required equipment, but this written revision cannot prove manual accuracy on a moving chart table or competence in command. It can teach the release controls that should surround every construction.

Start by stating the navigation decision: transfer a bearing, measure a route, plot a fix, advance a DR or EP, construct a course to steer, or test a clearing margin. Confirm the correct chart, scale, edition or exercise, exact endpoints, units, vertical datum where relevant, time and true, magnetic or compass reference before choosing the tool. A familiar plotter used from the wrong point is still wrong.

Separate three layers on the chart. Observation is what was actually measured and when. Construction is the geometric or arithmetic transformation, including any tidal vector, leeway or reciprocal. Decision is the route, position or limit released for use. Label enough of each layer for another navigator to reconstruct it under the vessel's procedure; do not disguise an assumption as an observation.

Use a set–plot–read-back loop. Set the direction, span, coordinate or vector; make a light traceable construction; then re-read the result using another suitable meridian, labelled compass rose, coordinate scale, distance transfer, arithmetic check or independent position source. MCA navigation syllabuses require chart construction of tidal effects and course to steer, while broader navigation guidance requires progress to be monitored and positions checked by appropriate means.

Resolve direction sense explicitly. A straight line carries two reciprocal directions, so endpoints, arrow and the T, M or C suffix decide which value belongs to the task. A bearing observed from the vessel to an object is plotted from the object along the reciprocal direction to form a position line. A remembered greater-than or less-than clearing-bearing rule is unsafe without the actual object, hazard, side and vessel geometry.

Withhold release when material conflict remains. Do not average two unexplained positions, erase the first observation or choose the more convenient reciprocal. Rebuild from the last reliable point, compare time, units, scale, source age and geometry, and preserve a conservative operational action or fallback until the charted margin is supported. Practical command may require slowing, maintaining an already verified safe sector, taking another observation or abandoning the intended route; the actual action depends on the yacht and situation.