To trace a route with a cras rule it's important to follow a few precise steps. The Cras rule, also known as the navigation rule, is mainly used in marine navigation to plot routes on a chart. Here's how it works:
1 âeuros Locate the arrow and place it in the direction of your route.
2 âeuros Place an edge of the règle or faith line on the route whose course you want to take. In our example, we're looking for the heading to go from the South Cardinal " Basse de la Chimère "at Cardinale Sud Search "in Quiberon Bay in Southern Brittany.
3 âeuros Match the center of the southernmost (lowest) protractor with a meridian (vertical line) or parallel (horizontal line). Slide the ruler, keeping it parallel to the road. In our example, we're positioned on a meridian.
4 âeuros Read the heading at the intersection of the meridian (in our example) and the protractor. Always read the number that is " right for the eye "Not the one that requires you to tilt your head to read it. Here, the reading is 142° (see enlargement on the right in the photo) and not 52°...
