Guideline to Selecting a Chart Plotter
What is a Chart Plotter?
Traditionally, marine navigators used paper charts and navigated using the chart and position finding equipment such as compass and dead reckoning devices.
Paper charts have been replaced with digitized electronic charts, both vector (multi layer) and Raster (single layer). Most people use vector charts in their chart plotters although some prefer the ‘paper like’ presentation of raster charts.
Dead reckoning devices have been replaced by Global Positioning Systems (GPS)
GPS is a satellite based positioning system and the devices used to transmit and detect signals from the satellites are called GPS sensors. Some manufacturers build the sensor into the product; however it is more common for them to be separate and connected by a low data rate serial link such as NMEA0183, NMEA2000 or a proprietary network.
The use of the chartplotter instead of paper charts is now commonplace for the recreational boater. However, total reliance on any single electronic navigational aid is not recommended and a back-up GPS and paper charts are advised.
What is the best choice for you?
One of the most significant decisions to make is how much room and where are you able to mount your chartplotter? In general, the larger the display you can fit the more useful the chartplotter will be. The comparison guide, in the Compare section, allows you to search for the largest screen plotter for the space you have available. The larger the screen the more the chartplotter cost, so the decision is a trade-off between the amount room available, screen size and cost.
Why is the size of display important?
Display size is important for a number of reasons. When you are out on the water, a large display allows you to see a lot more detail around your boat, details such as marker buoys’ and land mass. It also allows you to have multiple data windows on the display, such as large text displaying the boats speed and the depth below the boat, as well as keeping an eye on your current position. This becomes even more important if you want your display to be part of a multifunction system, such as radar and fishfinder functionality combined with your chartplotter; these products are generically referred to as combo products.
Display sizes are quoted in manufacturers’ specifications by reference to the diagonal dimension of the actual display area in inches or millimeters. This can be hard to compare to your available mounting area, therefore we have provided a search criteria allowing you to maximize your display given your available overall space.
Display orientation- Do you want vertical or horizontal?
It’s important to remember that some displays are mounted in a vertical orientation, referred to as portrait, and some horizontal, commonly called landscape. A vertical display will generally provide a better view of what’s ahead of the boat as more of the display area is used to display the map ahead of you. A horizontal display can be more useful for displaying two side-by-side pieces of data, such as a chart and a fishfinder display.
Depending on the where in the world you use your boat, display viewability—the ease with which you can see the image on your display—can be a major factor. All displays used above deck need to be designed to ensure that you can see them in direct or ambient sunlight. Equally, if your boating includes night use, the display needs to be adjusted to a low brightness level to ensure you can maintain your night vision.
Factors affecting viewability
There are a number of factors that impact viewability. For viewing in bright sunlight, a display with high brightness, good contrast ratio and a good quality anti reflective coating is essential. Unfortunately, there is insufficient publicized data in the specifications to make a definitive comparison without undertaking a life-like test. We suggest you ask your dealer for both advice and a demonstration of your short listed displays. Ensure the tests are undertaken in an area with plenty of highly reflective material that would replicate the reflection from the deck or body of your boat.
Maps- which cartography suits your needs?
Cartography or electronic maps have made significant advances in the recent years. Additional functionality such as 3D land and seabed, aerial photography and extended port data has added to the increase the maps usefulness.
The chart prices vary between fully functioning maps to basic navigational data. In some cases chart plotters are provided with pre-loaded maps that allow out-of-the-box functionality to a basic level of navigation.
We recommend that you select maps based on your own comparison of known areas of boating. If this is not possible, we would recommend you visit your local dock and ask around for some real life experience of how good certain maps are for your area. In some case it’s this choice that will narrow down your choice of plotter, as only a few manufacturers of plotters support multiple chart formats. The most common charts manufacturers are C-Map, Garmin (only used on Garmin chartplotters) and Navionics.
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