Since then navigators had to devote most of their time and effort to sorting out their position. Now, to a very large extent, GPS is usually relied upon to take care of that. The snag is that even with easy plotting techniques, human navigator working on a paper data can’t hope to keep up with the flow of information available by GPS receivers.
One solution is to use chart traceur gps espion scaled-down current position on an electronic chart. Of course , chartplotters acquire drawbacks, but their great strengths are that they change the position continuously, without human intervention, and without producing such very human errors as plotting 55°45′. 6N instead of 55°46′. 5N.
The simplest chartplotters do no more than that. Most, however , allow you to mark waypoints, plan routes, and measure directions and distances, while some can work out the training to steer to allow for tidal streams, or even plan the optimum route to follow to allow for forecast changes in wind strength as well as direction. They can then show how your actual position compares with your plan, give simple steering instructions with a human helmsman, or control an autopilot.
Chart plotters are a combination of three main groups of components:
o often the hardware
o the cartography
o the software
The appliance is the physical equipment (the casing, display, control panel, and for that reason on) and the internal electronics, such as the power supply, processor and also memory. They may be designed from the outset as chart plotters; they can be combined with some other equipment such as marine radar or autopilots; or they can be desktop or laptop PCs or even PDAs (Personal Digital Assistants).
The cartography refers to the electronic charts. They are available from various sources, in different formats and on several media, such as CD ROMs, floppy discs, PCMCIA memory cards, flash memory cards, or custom-made cartridges of various shapes.
The software is the link between the two, converting the electronic cartography into a form which can be displayed on the screen, enabling you to carry out navigational tasks, and communicating with other electronic devices such as a GPS receiver and autopilot.
Dedicated hardware / PC
In general terms, most dedicated hardware plotters usually are produced by specialist marine electronics companies, and are supplied with their own personal software already installed.
Dedicated hardware is good because it is strong and waterproof (at least to some extent) and is meant to operate from an unreliable 12-volt supply. Its control panel along with operating procedures are likely to have been designed specifically for use for a chart plotter, and although the choice of cartography is limited instructions usually to one particular supplier and one particular type of ink cartridge – the coverage is generally good and cartridges are around every corner.
PC plotters consist of specialist plotting software that can be filled into almost any personal computer, though laptops are the most popular for any job.
PC plotters are good because the initial outlay is comparatively low (especially if you already own a suitable computer) and because the computer itself is very much more versatile than a dedicated plotter. Some LAPTOP OR COMPUTER software can use cartography from a variety of different suppliers, although additional or updated charts are not always readily available.
Raster charts v vector charts
Although there are many different companies of electronic charts, the charts themselves can be separated into two main groups: raster and vector.
Raster graphs can be regarded as electronic photocopies of paper charts, generated by scanning a master copy of a paper chart, with much the same way as a fax machine scans a data that is about to be sent. The chart is converted into a vast number of tiny dots (pixels), and the place and colour of each pixel is recorded. Instead of transmitting this information down a telephone line, as a fax appliance does, the chart scanner stores it on the cartographer’s computer, from where it can be copied onto floppy cds or CD ROMS, and supplied to customers