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Chartplotters
| Applications | |
|---|---|
| Title | Chartplotters |
| Author(s) | GMV. |
| Level | Medium |
| Year of Publication | 2011 |
The GNSS 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 GNSS, loaded with proper software.
These products provide assistance in three major nautical activities: maritime en route navigation, collision avoidance (through means of AIS) and fishing activities.
Product Description
The GNSS chartplotters provided an improvement over handheld devices, because these are marine dedicated devices able to electronic represent nautical charts, over a navigation application. These devices can be mounted in the vessels and there are also some products with portable capabilities and internal GNSS antenna. Some products can be connected to an external GNSS antenna that usually offers better signal performance.
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.
The 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. Many of 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 that is shown in chartplotter, 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 equipment can be connected to external power sources and to external antennas.
Computer Connected to a GNSS receiver
This computer solution is usually used inside vessel's deck, where a computer unit is 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 advantage offered by this solution, is the memory and computational power capabilities, that will allow to run many software solutions, such as 3D bathymetric display, that would be impossible with a chartplotter unit
There also rugged laptops and desktop computers especially dedicated for the marine environment, which has the advantage that most upgrades can be done with software meaning lower maintenance costs.
Product Characterization
Typically the chartplloters 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 to the user 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 curretn 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 the reverse route.
- 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.
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 drop offs.
- Low visibility conditions, e.g, night and fog navigation.
- Receive direction instructions.
Electronic Charts
An electronic chart is mandatory for the user to operate the device. A GNSS chart is basically a digital representation of a nautical chart that are usually on paper. However these devices will not make a complete replacement for paper charts, despite the fact that chartplotter will be the primary navigation tool.
There are two basic format of charts that can be used in chartplotters:
- 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 your computer or GNSS units, because its a copy of the chart in paper format. The zoom function will increase or decrease the size of the elements in chart, degrading the usability in some situations.
- Vector charts: These are instructions of points, lines and polygons, that are used to draw the features into 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 zooming capabilities provides more usability to the user.
These 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 devices have larger, high resolution color screens, large memory, faster 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. Although, this units are quality products that provides sufficient navigation capabilities.
There are a number of marine electronics manufacturers such as:[3]
There several companies providing software and electronic charts, to be operated in chartplotters or in computers:
- C-map C-map NT+ , C-map Max , C-map Max Pro,
- Euronav,
- Garmin Blue Charts,
- Navionics Navionics Gold , Navionics Classic , Navionics Platinum.
Notes
References
- ^ a b c d Marine GPS Chartplotter, Info Centre
- ^ Maps GPS info Site, Marine GPS
- ^ Marine electronics reviews site