Reading almost any book on coastal navigation leaves most people with the impression that the running fix is not used much. This can not be further than the truth. Important to Coastal Navigation I find that while navigating along a coastline, the opportunity to complete a running fix presents itself more often than being able to obtain a two or three bearing fix. Once taken, a bearing to an object is later be “advanced” in time and compared with a new bearing of the same or a different object providing a fix. This new bearing can then be advanced to compare with another object coming into view later. Over time,…

The idea of a “Danger Bearing” is a simple one. Unfortunately, as navigators we often try to make is more difficult than it really is. Here we explore what danger bearings are and how to use them as a prudent mariner. A danger bearing does not take into consideration your vessel’s course, heading, or destination. It simply tells you which side of a line you are on, the “safe” side, or the “dangerous” side. It is Like an LOP A danger bearing is similar to a line of position. It is a bearing to an object. However, the bearing line is drawn from known safe water so that it passes…

What is an LOP In this topic, we discuss “Lines of Position.” A line of position (LOP) is a “line” to or around a target object. When an LOP is determined, you must be somewhere on that line. Because of this two LOPs provides an exact location. In other words, if you are somewhere along each of two different LOPs, you must be located at the intersection. In this case, “X” marks the spot. An LOP can be found a number of different ways. Bearing to an object A Range (two objects in line with each other) Depth contour line on a chart Distance Off an Object Angle off the…

The method of determining location used by a mariner is latitude and longitude.  Parallels – Lines of Latitude Lines of latitude run East/West marking off the degrees of an arc between the equator and each of the geographic poles. The equator is 0°. The North Pole is 90°N and the South Pole is 90°S. Lines of latitude are also known as “parallels” owing to the fact that they run parallel to each other moving up and down the globe. Meridians – Lines of Longitude Lines of longitude, also known as “meridians”, run North/South, beginning at one pole, and terminating at the other.  As with any sphere, there are 360° around…

Aids to navigation can pretty much be summed up as any object that might be used to aid in the process of safe navigation. Here, we will just be talking about some of the major aids found in the US Coast Guard U.S. AIDS TO NAVIGATION SYSTEM card. ATONs in the United States The U.S. follows a pattern of ATONs known as “Red-Right-Returning.” Lateral Aids Lateral Aids indicate the sides. Most often, the sides of a channel. They generally fall into one of four “types”. Red Marks – right side as seen entering from the ocean (returning.) Green Marks – left side as seen entering from the ocean. Red over…

TVMDC Direction on the Earth can be described using relationships to the North and South Poles. Known as true north, bearings based on true north are unchanging. In the modern world of GPS, equipment can be set to calculate and display true north without additional work on the part of the navigator. Related Pages Bearings Unfortunately, this isn’t true when using a compass. As we will be exploring in more detail below, a compass reads “magnetic north,” a direction based on the location of the magnetic north pole in relationship to the compass location on the earth. True vs. Magnetic North Any discussion of compasses must include a dialogue about…

Every craftsman requires tools Coastal Navigation requires the use of tools. Maybe not the type of tools you visualize when you think of tools, however, they are still tools. Without pencils, erasers, charts, tide tables and a way to draw lines on a chart it would be impossible to know where you are going, much less where you currently are. Related Pages Publications Plotting Tools You must have a few basic tools to accomplish the task of navigation. Essential Tools A few basic publications, such as a chart of the area, tide/current tables and Local Notices to Mariners. Dividers and some type of plotting tool, which is simply a device…

There are a number of plotting tools available to assist in piloting. Every navigator develops his or her own favorites over time, and most find that a very few are used on a regular basis. In its simplest form, you will need something to measure distance and something to draw straight, parallel lines. Dividers Two “legs” hinged at the top to allow the legs to be spread apart to a given distance, and then used to transfer that distance to other locations on a chart. Each leg ends with a sharp point. A warning – the hinge on “cheap” dividers will loosen over time. When this happens, they become worse…