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Chartplotters

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ApplicationsApplications
Title Chartplotters
Edited by GMV
Level Intermediate
Year of Publication 2011
Logo GMV.png

The chartplotters are dedicated devices meant to be used in maritime navigation activities.

There are two types of maritime products using GNSS technology, the handheld devices and the chartplotters units. There is also the option of using a computer connected to a GNSS receiver, running a chartplotter software.

These products provide assistance in three major nautical activities: maritime en route navigation, collision avoidance (using AIS) and fishing activities.

Product Description

The GNSS chartplotters provide an improvement over the generic handheld devices, because these are marine dedicated devices able to display electronic nautical charts and are tailored for nautical use being able to interface with other devices in the vessel. Chartplotters can be mounted in the vessels connected to an external GNSS antenna that usually offers better accuracy and availability while others are have a built-in GNSS antenna.

The chartplotters screens are considerably larger than the handheld devices and they provide usability improvements, such as large buttons and screens conceived to be visible in harsh conditions and direct sunlight.

Some chartplotter equipments must be feed by an Electronic Position Fixing System (EPFS), in order to be able to perform an automatic and continuous vessel's position update, using either a terrestrial hyperbolic radio navigation system such as LORAN-C or GNSS. But many of the current chartplotter devices integrate a GNSS receiver into a single unit.

These devices often integrate and display data from other devices like the radar or depth sounder. The radar overlay feature confirms the precise positioning relative to the chart. It can reveal inconsistencies and it is very useful in small screens, where this feature permit to see more content in the same display. It will work as a backup system in case of failure of GNSS signal.[1]

The information shown in chartplotters, usually includes water depth, obstructions on the path, environment, and other small but important data.[2]

Handhelds

The handheld receivers for marine utilization are usually a cheaper and portable solution, providing the same functions as the chartplotters. These devices, lack in usability due to the small buttons and screens, however, some models are waterproof, rugged, with floating capability and screens conceived to be visible in harsh conditions and direct sunlight.

The battery dependency and the GNSS internal antenna can often discourage the use of these devices. Even though, some equipments can be connected to external power sources and to external antennas.

Computer Connected to a GNSS receiver

This solution is usually applied inside vessel's deck, where a computer unit can be used for planning and for navigation.

Usually a computer will be connected to an external GNSS receiver and will be loaded with chartplotter software.

The biggest advantages offered by this solution, are the memory and computational power capabilities, that will allow to run many software solutions, such as 3D bathymetric display, that would be impossible with many of the current existent chartplotter units.

There are also rugged laptops and desktop computers especially dedicated for the marine environment. With these solutions the upgrades are often executed only with software, implying lower maintenance costs.

Product Characterization

Chartplotter in vessel's deck

Typically the chartplotters perform three main functions:

  • Straight line navigation: This is the waypoint navigation, where the user inserts a destination point, that can be defined as a coordinates position. The devices provide the following information: bearing, speed, and heading. The bearing provides the direction to follow, the speed of the vessel provides the estimated time of arrival to the destination while the heading provides the current vessel's direction, which is also helpful in order to make navigation corrections.
  • Tracks: This is the waypoints recording function, analogous the functions existing in many handheld equipments. It is important, for instance, in narrow waterway navigation, in order to avoid obstruction such as rocks, or to execute reverse route navigation, to the starting point.
  • Routes: This is the waypoints navigation, where the user inserts a collection of waypoints, similar to the function provided in other navigation devices. The chartplotter will provide directions from one point to the other.

In addition to the navigation functions, a chartplotter device allow a helmsman to perform the following tasks:[1]

  • Identify vessel's position in relation to anchorage zones, marine reserves, different channels or shipping lanes.
  • Obtain awareness of where exactly the water hazards are located.
  • View certain underwater details including reefs, sand banks and other underwater rises and dropoffs.
  • Low visibility conditions, e.g., night and fog navigation.
  • Receive direction instructions.

Electronic Nautical Charts

An electronic chart is mandatory for the user to operate the device. An electronic nautical chart is basically a digital representation of a paper nautical chart. However these electronic charts will not be a complete replacement of paper charts, since even if the chartplotter is the primary navigation tool the vessel should have paper charts as backup.

There are two basic formats of charts that can be used in chartplotters:

  1. Raster charts: These are the geo-referenced version of a paper chart. This format provides detailed information, but it requires large amount of memory and processing power from the computer or GNSS units, because its basically a scan of the chart in paper format. The zoom function will increase or decrease the size of the elements in chart reducing the usability in some situations.
  2. Vector charts: These are composed by mathematical representations of points, lines and polygons, that are used to draw features onto the chart. The biggest advantage is the capability to view the information as layers that can be added or removed from the chart. Each element on the chart is an object with detailed information, that can be accessed. The usability is not affected by zooming since the features are redrawn depending on the zoom level.

The electronic nautical charts are usually found in proprietary formats, for instance, Navionics, Lowrance or Garmin.[1]

Fish finders

A fish finder is a marine electronic device that searches with sound waves and converts the returning signals into a picture on a display screen. Some multi-function chartplotters combine fish finders into the same chartplotter unit, providing a powerful GNSS tool with useful capabilities for fishers.[1]

Product Examples

The most expensive chartplotters have large and high resolution color screens, large memory, fast processors, multi-function capability or the ability to be linked to other equipments. Cheaper models have smaller screens, fewer features, slower processors and less memory. Despite this these units are quality products that provide adequate navigation capabilities.

There are a number of maritime electronics manufacturers such as:[3]

There are several companies providing software and electronic charts, to be operated in chartplotters or in computers:

Notes


References

  1. ^ a b c d Basic Navigation with a Chartplotter, Tom Lochhaas
  2. ^ Maps GPS info Site, Marine GPS
  3. ^ Marine electronics reviews site