Marine GPS Information

GPS units are essential equipment on today's boats. Units range from inexpensive handhelds to full blown chart plotters. Many GPS units have built in mapping or accept digital maps to help the user navigate.

Boaters can choose from a simple handheld unit or choose a fixed mount unit. Both types have advantages and disadvantages. Many boaters keep a hand held unit for safety even if they also use a fixed unit. One nice feature for many handhelds is a special cradle with a power cable for use when under way.

Configuring your GPS is important in order to navigate accurately. Among the parameters to be chosen are map datum, navigational units, data output and the unit's course format. Each of these elements should be understood and set before using the unit to navigate.

Map datum refers to the original algorithm that the paper chart was designed with. In order to compare a GPS position to a paper chart, both the GPS unit and the chart must use the same datum. WGS84 is the most common datum in use among American boaters. NAD83, the other common datum is virtually the same. International charts use a variety of datums so mariners are advised to always check navigational charts and configure the GPS unit accordingly.



Navigational units can usually be set to miles per hour, or knots. Since water is measured in nautical miles, it is preferred to set GPS units of measure to nautical miles and knots. It is also relevant to remember that your paper chart typically displays units in nautical miles. A degree of latitude is 60 nautical miles, and a minute of latitude is 1 nautical mile. Knots are important as 1 knot = 1 nautical mile.

Another setting to choose is course up or North up. This will make the plotter display the chart or grid always with the course oriented in front or always in a North up orientation.

GPS units can store the near exact location of a given point of reference. Modern GPS units often come with a wide range of waypoints pre-programmed. In addition, the user can also store, name and recall custom waypoints. This allows boaters and fishermen to store and maintain lists of fishing hotspots, navigational marks and other important locations. GPS units also store routes and plotting history so the mariner can call up a pre-programmed path to follow or review a vessel's earlier path.

Waypoints, routes and track data can all be downloaded, stored, edited and uploaded back to the GPS via the users computer or other device. This can be a vital feature that allows the user to save important data. Data from one GPS can also be shared or cloned to another unit. All these features allow users to easily manage a vast amount of information effectively.

GPS units can be a great navigational tool when used properly, although GPS units should never be relied on as a primary means of navigation. A fundamental understanding of basic navigation is vital to successful operation of these indispensable tools.

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