Sale of Marine Compasses
Marketplace topRik presents a catalog with prices for marine compasses for boats. Choose and buy a model that exactly suits your needs from the world's best manufacturers of navigation devices and equipment – Plastimo, Riviera, etc.
If you have questions about the range of navigation compasses and their choice for a particular yacht, get a free consultation from experienced sailors right now. topRik experts will give you professional advice by phone, through the website contact form or by email ([email protected]).
A compass is the main navigation device used to determine the ship's course and directions (bearings) to various objects.
The prototype of modern compasses is believed to have originated in Europe at the turn of the 12th-13th centuries, when a magnetic needle was placed in water on a cork base and spontaneously oriented along the lines of the Earth's magnetic field. Then, structurally, the arrow moved to a vertically located needle, the so-called card appeared, that is, a circle divided into points, as well as a suspension, thanks to which the ship’s pitching ceased to affect the accuracy of the compass.
Types of Nautical Compasses
Further development of shipbuilding led to the improvement of this main navigation device. The modern yacht owner can afford to choose from several types of marine compasses. On larger ships, all types can be present at the same time.
Magnetic Compass
This is the simplest and most ancient design, based on the interaction of a magnetic needle with the Earth's magnetic field, as a result of which the needle takes a position pointing to the north and south magnetic poles.
The design of a modern ship's magnetic compass includes:
- a pot with a card;
- binnacle;
- direction finder;
- deviation device.
A magnetic compass is a navigation device that implements the physical principle of the ability of a magnetic needle to orient itself along the magnetic lines of the Earth, with the help of which the ship’s course is determined, as well as the directions to objects directly observed by the navigator. An ideal magnetic compass points north along the Earth's magnetic meridian, which passes through the magnetic poles. The accuracy of magnetic compasses decreases as you approach the magnetic poles.
When determining the direction of movement of the ship, it is taken into account that the magnetic and geographic poles do not coincide, and the angle between the corresponding magnetic and true meridians, called magnetic declination, is non-zero. In addition, oscillations of the Earth's magnetosphere and the own magnetic field of ships, the design of which contains magnets, introduce interference into the readings of the magnetic compass, called magnetic compass deviation. The direction indicated by a magnetic compass corresponds to the compass meridian, so the deviation of a magnetic compass is defined as the angle between the magnetic meridian and the compass meridian. To determine the true heading, magnetic declination and magnetic compass deviation are taken into account.
Magnetic compasses contain a freely rotating compass map that aligns with the Earth's magnetic field and points in the direction of north. Small magnetic fields on board, caused by metal (steel steering wheel or iron block), magnets (speaker or microphone), or conductive wires, can distract the compass from pointing north.
This deviation must be corrected by moving the compass away from local magnetic interference (if possible) or by adjusting small compensating magnets inside the compass (using a process called compass swing). For deviations that are too large for compensating magnets, typically greater than 20°, a deflection table may need to be created.
The development of the idea of a magnetic compass was realized after the invention of electromagnets containing two windings - a stator and a rotor. In this design, the Earth's magnetic field is used as a stator, and a frame with a winding inside the compass is used as a rotor. When moving in the Earth's magnetic field, the frame deflects properly, maintaining its relative orientation in space. The electromagnetic type of compass has a significant advantage over the magnetic one, since it does not have interference from external metal elements (for example, the skin of a vehicle) moving in the same direction. However, such a compass requires high speed to operate, so its main application was in aviation.
Gyroscopic Compasses
Gyrocompasses indicate direction using gyroscopes, the operating principle of which is based on the relationship between the rotation of the Earth and the rotating disk of the structure. The so-called precession of the gyroscope, which occurs as a result of the earth's rotation, allows you to select the desired direction.
This type of compass has a significant advantage over all magnetic ones, since it points not to the magnetic poles, but to the true north and south, through which the Earth’s conventional axis of rotation is drawn. This property is more useful for proper navigation. Another plus is that gyroscopic compasses, like electromagnetic ones, do not depend on the presence of metal objects nearby.
Electronic or Digital Satellite Compasses
With the development of satellite technologies, models of compasses have appeared whose operation does not depend on either the Earth’s magnetic field or its rotation, since they are guided by satellite signals. Satellite compasses are highly reliable, integrated into ship systems, resistant to interference, and widely used in the modern world.
Satellite electronic compasses are a combination of all devices of this kind, compatible with ship navigation equipment and incorporating all the latest technical achievements.
Electronic circulation compasses measure the relative strength of magnetic fields passing through two coils of wire. Using sophisticated electronics, these sensors can determine the direction of the Earth's magnetic field. Of course, they cannot ignore the effects of local magnetic fields created on the boat by metal parts or loudspeaker magnets, but they compensate for those areas that do not vary in location or strength. These are compasses with global magnetic correction.
The operating principle of the electronic compass is as follows:
- based on signals from satellites, the coordinates of the satellite navigation system receiver are determined;
- the moment in time at which the coordinates were determined is recorded;
- a certain period of time is waited;
- the location of the object is re-determined;
- based on the coordinates of two points and the size of the time interval, the movement speed vector is calculated.
One of the advantages of electronic compasses is that their sensors can be mounted remotely in many cases. This allows the sensor to be placed in such a way that it will be least affected by interference from metals. Of course, this increases the complexity of installation.
All types of compasses presented in the topRik marketplace meet the basic requirement for their use on sea vessels - they are waterproof navigation devices that are protected from rain, salt and corrosion.
Almost all models are backlit compasses, which allows you to use them at any time of the day and in any weather.
Installation of Marine Compasses
The procedure and conditions for installing marine compasses depend on their type. But we can formulate general recommendations:
- choose the most visible and convenient location for mounting the compass for the helmsman;
- the compass must be aligned with the longitudinal axis of the boat;
- lay electrical wires from the compass;
- do not install the compass near devices containing magnets or near an engine;
- compensate for the magnetic field of the night light wires by clustering them together (if possible).
Check for deviations caused by magnetic objects. Deflection is an error caused by the iron and steel on the boat (hardware and fittings) that causes the compass to point toward magnetic north. Compass adjustment is complex and usually requires an expert (called a compass adjuster) to do it correctly.
Depending on the type of installation, fasteners are also selected, although leading manufacturers usually supply them complete.
For hidden installation, the compass is installed in a cutout on the surface, with it half recessed and half exposed to the surface.
Compact brackets are very versatile because the bracket can be installed on surfaces with different angles of inclination. They can also be easily removed for storage or security.
Bulkhead compasses are suitable for small cruising sailing yachts and small powerboat instrument panels. The stern bulkhead of a sailboat provides good visibility, but sometimes deviates from the vertical. Some compasses can be mounted at angles up to 45°, but others require an alignment block for the internal gimbals to function properly.
Surface compasses are located on the surface and installation is simple as there is no need to cut large holes.
Circulating compasses are also mounted on a surface or steering pedestal, as on rudder-driven sailboats. Owners of motor boats choose them when there is no space under the mounting surface.
FAQ
What additional features might be useful in a marine compass?
The backlight in the marine compass will greatly facilitate working with it at night or when visibility is poor. The same applies to the anti-glare screen - only it will help the helmsman in sunny weather.
For yachtsmen, a compass with a clinometer for installation on a sailboat will be useful.
Built-in magnetic and heading deviation compensation adjustment will provide a more accurate heading.
What to do if the compass points in the wrong direction?
If you do not have experience in calibrating any type of compass yourself, then it is better to entrust the setup of the device to professionals. Our experts are well aware of all the options for this procedure, but are not ready to present it for general use, so as not to harm novice sailors and their yachts.
What parameters to consider when choosing a compass for international voyages?
Requirements for the characteristics of a compass on sea vessels are regulated by IMO documents, which should be followed first. In addition, the boat owner should take into account the dimensions of the yacht when choosing a compass in order to resolve the issue of the type of device and its location.
Consider all your needs in different sailing conditions to choose the right option: backlit, anti-glare coating, built-in deviation compensation setting, etc.
Be sure to check the durability and weather resistance characteristics: the compass must withstand harsh marine conditions, including exposure to water, salt and ultraviolet rays.
The ability to adjust is one of the most important selection criteria. The compass must be able to calibrate and compensate for deviations to provide accurate readings regardless of the boat's magnetic influence.
Check the compatibility of the new device with other navigation systems on the yacht. The compass must be compatible with them to ensure maximum integration and improved navigation capabilities. This is especially true for digital models, including satellite ones.