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Autopilots – The primary self-steering gear was introduced in the 1920′s to control model yachts but it was not until 1948 that the principle was employed to full scale yachts. Standing at the helm for lengthy periods, monitoring instruments and keeping a good look out may be very tiring. An autopilot relieves the helmsman from steering the rectify course leaving him free to maintain a proper watch. The autopilot may be set to either steer a compass course or a course relative to the wind. A fluxgate compass or electronic wind indicator feeds selective information to a microprocessor which then makes the necessary rudder movements to return the vessel to it’s required course. The mechanical power is used to the rudder by either electric linear activators, hydraulic pumps or rotary drives. GPS/Chart plotters may be used to input navigational instructions to the autopilot. Battery Chargers will keep batteries to the full or entire extent charged thereby extending their working life. Chart Plotters – Typically a chart plotter comprises of an antenna, mounted high on the boat, to track GPS signals and a display unit sited either at the at the navigation station or the helm of the vessel. The vessels position is sent from the antenna to the display unit which in turn shows it graphically on the chart. The Chart itself will look similar to it’s paper equivalent and show depth, land mass, navigational aids such as bouys and potential dangers in the form of wrecks and obstructions. The user may add way points to the chart and zoom in and out of the display. Chart plotters may be connected to drive an autopilot and/or send GPS info to a fish finder or radar. They may also interface with a laptop enabling complex passage planning to be done away from the boat and then entered into the chart plotter after arriving at the boat. Magnetic Transmitting Compasses work like established compasses using magnets to determine the vessels orientation to the earth’s magnetic field they then transmit the boats heading to an electronic display. They make steering posing no difficulty than with established compasses because they display steadier headings and do not suffer from the “lag” that occurs when making a turn. They may interface with chart plotters, autopilots and radar. Fluxgate Compasses consist of two pieces of readily completely filled magnetic material with coils wound round them in opposing directions. AC current is passed through the coils and the material is completely filled in one direction and then the other. The earth’s magnetic field affects more or less the time at which saturation occurs, earlier in one coil and later in the other. The divergence is then calculated giving an output proportional to the earth’s magnetic field. They are exact to 0.1 of a degree. Their output may be displayed digitally to the helmsman or they may interface with autopilots, chart plotters and radar. Echo Sounders work on the same principle as sonar. A transducer emits a narrow beam of high frequency sound. This is reflected by any solid objects and the time amongst transmission and receipt of the echo is measured. The speed of sound through water is recognise and so the range or distance to the sea bed may be calculated. That is then displayed in metres. Forward Looking Sonar (FLS) enables you to see the underwater hazards before you’re genuinely on top of them. A typical range for a FLS is 150 metres. An Emergency Position Indicating Radio Beacon (EPIRB) is a piece of instrumentation designed to float free of a vessel in distress. It then sends a radio signal that may be detected by Search and Rescue Satellite Aided Tracking (SARSAT) satellites. They relay a message to a ground station that in turn may instigate a search and rescue operation. Fish Finders use the same technology as sonar. A narrow beam of high frequency sound is transmitted by a transducer, this is reflected by solid objects such as the sea bed. By manufacturing this engineering fishfinders provide displays that show where the fish are and they may discern among bait fish and larger species Global Positioning System (GPS Receivers) – This scheme was in the first place designed for military intents and is owned and operated by the United States Department of Defence. 24 satellites are arranged in a “birdcage” around the globe, they are positioned in such a way that at any place on the earth’s surface a direct line of sight may be conventional to a minimum of 4 satellites. A repair is received by measuring accurately the distance among a satellite and the GPS receiver at a precise time. Because the precise position of the satellite is known, these distances provide position lines which are converted by a microprocessor within the GPS receiver to read outs of latitude and longitude. The log is employed to measure the boats speed through the water. A paddle wheel or impeller, mounted under the waterline is turned by the flow of water, this generates electrical impulses that are fed to a microprocessor that displays both speed and distance run. Inverters – On most boats today you will find domestic instrumentation of one sort or another. For on board amusement there are televisions and stereo systems. With the popularity of chart plotters comes the PC or laptop. Maintenance often times requires the use of power tools. Liveaboards might have a washing machine, dishwasher or microwave. Can take 12v, 24v or 48v supply and convert it to a stable 110 v or 220v AC supply. Navtex may perchance best be described as a continuously altered telex service providing navigation and weather data within specified areas. An on board receiver, tuned to 518kHz, the global Navtex frequency, if left turned on will either print out or display the latest massages sent from a local station. The service is available up to 400 miles from the coast. Radar enables you to see what other than as supposed or expected would be invisible. They offer biggest gain at night and in fog or rain and are of peculiar value when close to shore or in busy shipping lanes. They consist of an antenna and a display. The antenna sends out a stream of RF energy which is reflected back off hard objects. When this energy is bounced back it is converted to a signal which displayed to the user. The antenna rotates each few seconds, the display continuously calculates the direction of the antenna and so a precise bearing to the target is calculated. The time is measured for the energy to be reflected and so the distance of the target is likewise displayed. Satellite Phones consist of an antenna, a modem and a normal handset. They are powered by an iridium battery. Their range is anyplace covered by in Inmarsat Mini-M satellite. Voice, fax, email and selective information may be transmitted. Satellite TV requires an antenna and of course a television. Reception is available within a “footprint” which is based on EIRP (Effective Isotropic Radiated Power) of a transmitting satellite. The EUTELSAT together with the two ASTRA satellites cover Europe. NILESAT and the two ARABSATs cover Africa and the Middle East. Good coverage is also available in North, Central and Southern America. SSB Radio has a range of assorted thousand miles. You will need an FFC license, or the equivalent in whichever country you plan to operate it. Power consumption is a consideration. Up to 100 Watts may be required for transmission. SSB radio requires assorted items of equipment. A transceiver capable of SSB operation, An antenna, this will have to be 8 metres long and in exercise most boats use a backstay or shroud for the aim having fitted the necessary insulators. An antenna tuner matched to the transceiver model. If you want to send email you will also need and radio modem and computer. VHF Radio The power required to transmit is minimal, all sets have the option of transmitting on either 1 Watt or 25 Watts and the lower power must be applied whenever possible. Unlike telephones that grant you to both talk and listen at the same time most VHF sets require you to press a transmit button prior to talking. This is known as simplex. Duplex sets are available but are much more expensive. VHF radio waves travel in straight lines so the aerial will have to be mounted as high as possible, preferably at the masthead. Most helpful customer reviews 82 of 85 people found the following review helpful. 28 of 28 people found the following review helpful. 26 of 26 people found the following review helpful. The book explained everything very simply and thoroughly. I am not sure if experienced mechanics (diesel) and electricians would find it useful, except as a resource, but if you are even a little unsure of your abilities you cannot go wrong with this book. As a result of reaading the book several times as needed, and receiving a bit of instruction from the knowledgeable captain, I am now fairly competent.
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