Theoretically, on the ship, you can use any GPS navigator wearable, car, and so on. He will cope with two main tasks – determining coordinates and heading to a given point. But the operational features of marine GPS navigators at sea present specific requirements that only a specially designed marine device can fully meet. What are these features?
Marine and ship GPS navigators, features of use and application of ship GPS navigators.
On solid ground, the GPS-receiver creates a lot of amenities, but in addition to it, as a rule, there are motionless landmarks, a road, a path, and terrain elements along which you may be able to find a way in case of failure or error. At sea, often in your field of vision only uniform waves from horizon to horizon.
Distant lighthouses, islands, coastal line, if visible, often merge into a barely distinguishable strip, which is difficult to identify and determine the distance to it, even with extensive experience. In the eyepieces of 7-fold binoculars when rolling, these objects perform unthinkable dance, sometimes to the utter impossibility of observation. In the dark, in rain, fog or storm, your field of vision is often limited to the nearest wave crests of a dozen or two meters. And navigational hazards – reefs, shallows, rocks, other sunken ships and so on, are also found in the open sea, out of sight of the coast.
If, on a hiking or car trip, due to a navigation error, you are just late for your destination, in the worst case, spend the night in the forest, use up fuel and stop on the road, experience stress, etc., then there’s a hundred meters error at sea can lead to the death of the ship, cargo, people, other destructive consequences. Therefore, marine navigation – one of the main areas of GPS application – can only be compared in liability with air navigation. The rules of safety, maritime practice, navigational service, developed by centuries of experience, are written in blood.
Life can literally depend on the reliability of your ship’s GPS navigators and other navigation devices, their ease of use, map quality, and your navigation skills. From here, in addition to the increased requirements for the GPS navigators themselves, there follows the requirement of their mandatory duplication by other means of navigation. Thus, not a single vessel, no matter what electronic innovations it is equipped with, can go to sea without a simple magnetic compass.
Extreme operating conditions for marine and ship GPS navigators.
On a vessel, especially a small one, always high humidity, pitching, even in fine weather. In a storm, when the cost of an error is especially high, your devices will splash and fill with water, you will have to quickly and accurately read their readings during bumps, rolls, with busy hands. Fatigue, fear, stress, motion sickness will “help” you make a mistake. In case of problems, you can always stop on the sidelines on the shore in a hike or trip, eliminate the malfunction, think, relax. There are no curbs in the sea.
No matter how bad you may be, you can stop only by reaching the harbor. Hence the requirements: reliability of devices and their power supply, necessarily splash-proof or hermetic design, simple, no-frills, but thoughtful, intuitive control system. The display should be in the largest font possible. Of course, preference should be given to specialized navigators of well-known companies with experience in the marine area. Of course, you have to come to terms with the fact that any equipment with the designation marine for objective and subjective reasons is more expensive than “land” counterparts.
Stationary execution of marine and ship GPS navigators.
As a rule, a GPS navigator is installed permanently on a ship, it works for many hours in a row, often around the clock, and is powered not from batteries, but from an external source. The wearable device can be equipped with a bracket and an external power adapter, but for extra money, and in a stationary navigator all this will be included in the standard package. In addition, the size of the display has already been mentioned above. However, even on large yachts, they often hold a portable navigator powered by batteries as a backup. If a portable device is purchased, then it should be convenient for working in a stationary version.
In this regard, for example, the Garmin eTech series with its small and tight buttons on the sides, although brackets are made for it, is most likely not the best choice. Therefore, you should prefer models with a large screen and buttons on the front panel. A built-in compass sensor for stationary installation is likely to be useless. The data of the compasses built into the navigators produced today are not transmitted via NMEA, and they cannot be used in other on-board devices. On the contrary, the information of the built-in barometer will be very useful to the skipper.
Convenience of management on sea and ship GPS navigators.
It is better to choose a device with a large number of buttons. This provides faster access to functions through dedicated buttons, rather than a consistent selection of menu commands. When pitching and in extreme situations, this is important. A convenient option is devices with multi-function keys (Soft Keys), and / or with a numeric keypad for direct entry of numerical values. Mandatory for marine and ship GPS navigators sound signaling of a number of events.
Displacement from anchorage (demolition from anchor).
Arrival at destination.
Remote antenna on marine and ship GPS navigators.
If the GPS-receiver is installed in the cockpit, on the bridge, in the wheelhouse or cabin made of fiberglass, in addition to a multi-layer “sandwich” with wooden layers, then, as a rule, a built-in antenna is sufficient. In all other cases, ship GPS-navigators will require a remote antenna. Some navigators have a removable antenna on the BNC connector, which can be removed on a special extension cable of limited length.
But the best choice would still be a special marine active antenna. Such mushroom-shaped antennas for ship GPS navigators are available with internal thread: standard mount for marine radios and other antennas. As a rule, the threaded lower part is removable. After removing it, the antenna can be installed flat on a flat surface. Through a coaxial cable, DC power is supplied to the antenna from the GPS receiver. Many ship GPS navigators have an entire GPS receiver assembled in one compact housing with an antenna.
The ability to integrate other devices with marine GPS navigators.
On the ship often there is a need to connect different devices and exchange information between them. For example, if the boat has two control posts, in the wheelhouse and on the upper bridge, the information should be duplicated on the displays of both posts. On sailing yachts, the navigator often works below, in the cabin, and information about the course, direction to the waypoint, speed and depth should be displayed in the cockpit in front of the helmsman on an auxiliary display, the so-called repeater (repeater).
GPS data is transmitted to the radar so that it can orient the screen according to the countries of the world, determine not only course angles and ranges, but also the coordinates of targets, to a radio station with a DSC (DSC-digital selective call) system that automatically sends a distress signal with coordinates, etc. d. Often GPS is docked with autopilot. To do this, devices must have data input / output ports that work either according to the standard NMEA protocol or according to proprietary protocols. In the first case, the devices are compatible with any devices that support this protocol, but the functionality of information exchange is limited.
The second option provides more options, but requires the purchase of part or all of the equipment of one company. On the other hand, proprietary instrumentation systems can be equipped with an adapter with an NMEA port, of course, at an additional cost. Devices that even run on NMEA often do not support all types of messages; or just input, or just output.
For example, having bought an echo sounder with an NMEA output, you hope to connect it to the chartplotter so that the depth is also displayed on its chartplot, but this will succeed only if the plotter supports not just NMEA, but specifically entering depth messages (DBT or DPT). The number of NMEA ports matters. Typically, only one NMEA device can be connected to a single port. When choosing devices, you must consider the compatibility and the possibility of future expansion of your on-board instrument network.
Based on materials from the book All About GPS Navigators.
Naiman V.S., Samoilov A.E., Ilyin N.R., Sheinis A.I..