Conceived and designed by Yvonnick Guéret in the 60s, the Breton protractor has undergone a number of variations that continue to improve its ease of use and avoid the reading errors that can occur with other protractor-type rulers. Such is the case with the Flash Tide Rapporteur Breton ruler, with clearly legible red markings to stand out against the background map.
Key points of the Breton protractor
1 - Reading window with integrated magnetic variation
2 - Boat direction, course to steer
3- - Central datum line or ruler edge
4 - Visual reminders of magnetic and compass declination
5 - Integration of drift according to wind angle
Using the Breton protractor - Determining course from A to B on a chart
step 1
Position the edge of the ruler on points A and B. As A is the starting point, check that the boat symbol on the ruler is heading towards B.
step 2
Turn the central rose to align North with North on the map. To do this, use the ruler's grid to align it with a vertical latitude or horizontal longitude on the map. Choose the one that's easiest to align.
To do this, it may be useful to move the ruler, taking care to keep it on the road between A and B.
step 3
Read the heading in the window. Here, the heading is 52°. You will then need to correct this heading with the magnetic declination before communicating it to the helmsman.
Other models of Rapporteur Breton
Flash Tide offers two other models of Breton protractor to make reading its rulers easier.
- The Brocémer Rapporteur de Navigation ruler resembles the Rapporteur Breton in our example, but is simplified for easier, more fluid reading.
- The Antares Ruler combines both a Breton Rapporteur and a Cras Ruler. This means that the crew member who has to use it at the chart table has a choice of two worlds.
