Efficient Chart Work Techniques

Keeping the chart clean is essential for safe navigation. Rub out previous workings before starting a new passage so the chart is not cluttered with old courses, bearings, and position marks. During a passage, use neat, light pencil lines and standard symbols — a small triangle for a fix, a small circle with a dot for a dead reckoning (DR) position, and a small triangle inside a circle for an estimated position (EP).

Label every plotted line and position clearly. Courses are written along the course line as a three-figure True bearing (e.g., 045°T) with the speed underneath or beside it. Position lines (bearings) are labelled with their three-figure True bearing at the end nearest the object. Times are written in four-figure 24-hour format next to each fix or position mark (e.g., 1435).

Under exam pressure, accuracy and speed come from disciplined habits: always use a sharp pencil, keep dividers set to a convenient span when walking distances so you do not have to re-measure each time, and double-check every bearing before drawing it. Common mistakes include misreading the compass rose (reading the reciprocal), plotting from the wrong point, using the longitude scale instead of the latitude scale for distance, and forgetting to apply variation or deviation.

A Portland or Breton plotter is faster than parallel rulers for most people because you do not need to walk to the compass rose, reducing both time and the chance of slipping. When using parallel rulers, keep your eye level directly above the ruler edge to avoid parallax error — looking at an angle makes the ruler appear to be on a different line than it actually is. Use a soft eraser and rub gently to avoid damaging the chart surface; a hard rubber or heavy pressure can remove printed detail.