- The compass rose dates back to the 1300s and its primary purpose is to display cardinal directions.
- There are 4 cardinal directional points on the compass rose (N, E, S, W).
- The contemporary compass rose shows both true north and magnetic north.
What Is The Compass Rose?
The compass rose is quite an old design element that can be found on maps, buildings, and monuments and dates back to at least the 1300s. Initially the compass rose was referred to as a "wind rose" because it indicated the direction of the wind. Over the years, the compass rose design has been given many different makeovers. However, while each of these roses have been different in design, they have all been built with the same principle in mind: direction.
How Do You Read A Compass?
For a compass to be effective, you must be able to read it. A compass is like the face of an analog clock but, instead of having minutes, it has degrees. True North, which would be 12:00 on a clock, is read as 0 or 360 on a compass. Due East, 3:15 on a clock, sits at 90. South, which looks like 6:30 on the clock face, is read as 180. Lastly West, which looks like 9:45 on your clock, sits at 270 on the compass.
The compass rose's primary purpose is to display the cardinal directions in a readable and usable format. The eight major winds, or major directional points on a compass, are North, East, South, and West and their bisections (NE, NW, SE, SW). The four directions are called the cardinal points or cardinal directions. The four bisectors - Northeast, Southeast, Southwest and Northwest - are the primary inter-cardinal directions. Together, these eight directional points make up the eight principle winds (or points) of the 8-point compass rose.
What Is a 16-Point Compass Rose?
A 16-point compass rose is constructed by bisecting the angles created by the eight directional points. The half-winds are the combinations of the principal winds to each side, and provide even more specific directions such as: North-Northeast (NNE), East-Northeast (ENE), East-Southeast (ESE), South-Southeast (SSE), South-Southwest (SSW), West-Southwest (WSW), West-Northwest (WNW) and North-Northwest (NNW). Notice that the names of the half-winds are constructed simply by combining the names of the principal winds on either side. The cardinal wind (N, S, W, E) is listed first, and the ordinal wind (NW, SW, etc.) second. By measurement, these eight principal winds and eight half-winds are placed at 22.5 angles and, taken together, yield the 16-wind compass rose.
What Is a European Compass Rose?
Finally, the most complete European compass rose bisected half-winds in order to produce the 32-wind compass rose. The sixteen quarter-winds are named "X by Y", so that you get the directions: North by East, Northeast by North, Northeast by East, East by North in the first quadrant. Keep going and you will get East by South, Southeast by East, Southeast by South, South by East in the second quadrant; South by West, Southwest by South, Southwest by West, West by South in the third quadrant; and finally, West by North, Northwest by West, Northwest by North and North by West in the fourth quadrant. The old mariners were required to memorize and be able to recite each of the 32 points on a compass rose.
How are all of these points depicted on the actual physical "face" of the compass rose? First, the four cardinal points will always have the largest identifying features so that the mariner can take a quick glance at the rose to get the general direction or heading. The inter-cardinal winds, or points, will have slightly smaller identifying features, and the half and quarter winds will have the smallest marks. Without this graduated change in features, the rose would appear as a series of bisecting lines making it difficult to quickly determine your direction.
The Importance of Understanding Your Compass
What do all of these "ancient mariner" details mean to you? Before you leave the dock or boat ramp, always mark your location on your chart. This will give you the beginning of a bearing or direction point. Whether you are boating offshore, or just running up and down the lake or waterways, check your compass and orient yourself to your original bearing point. Remember, the 4 cardinal points (N, E, S, W); are the largest points on the graphic display face, and a simple glance should easily tell you your general (cardinal) direction. For example, if your original bearing point was North and your day of boating has taken you in a southerly direction, when you head home, steer your boat back towards the North. Keep in mind that a prevailing current will cause your boat to drift in its direction. This "drift" will pull you from the bearing point you are using, and you will no longer be travelling in a straight line. If this happens, you will need to adjust your course in order to reach your destination.
The compass rose will always be located on a paper chart, so you can plot your position and course heading with it if you do not have a compass. It is prudent to plot your position on a paper chart at least once an hour, even if you have electronic charting programs. Why? If you encounter a failure with your electronic equipment or the battery source for your electronics failed, then you can use your paper chart as a reference to orient yourself and make it back home. Today the contemporary compass rose shows both true and magnetic north. The outside ring represents true cardinal directions while the inside ring denotes the magnetic cardinal directions. Remember that "true north" is the geographical location of the north pole, while "magnetic north" refers to the "north" that a compass needle will point. Be sure to become familiar with the differences between your compass rose and your compass.
Be safe and don't let your 3 hour cruise turn into a Gilligan's Island adventure!