| Autopilots The first self-steering gear was | | | | United States Department of Defence. 24 |
| introduced in the 1920's to control model yachts | | | | satellites are arranged in a "birdcage" around the |
| but it was not until 1948 that the principle was | | | | globe, they are positioned in such a way that at |
| applied to full scale yachts. Standing at the helm | | | | any place on the earth's surface a direct line of |
| for lengthy periods, monitoring instruments and | | | | sight can be established to a minimum of 4 |
| keeping a good look out can be very tiring. An | | | | satellites. A fix is obtained by measuring |
| autopilot relieves the helmsman from steering the | | | | accurately the distance between a satellite and |
| correct course leaving him free to maintain a | | | | the GPS receiver at a precise time. Because the |
| proper watch. The autopilot can be set to either | | | | exact position of the satellite is known, these |
| steer a compass course or a course relative to | | | | distances provide position lines which are |
| the wind. A fluxgate compass or electronic wind | | | | converted by a microprocessor within the GPS |
| indicator feeds information to a microprocessor | | | | receiver to read outs of latitude and longitude. |
| which then makes the necessary rudder | | | | The log is used to measure the boats speed |
| movements to return the vessel to it's required | | | | through the water. A paddle wheel or impeller, |
| course. The mechanical power is applied to the | | | | mounted below the waterline is turned by the |
| rudder by either electric linear activators, hydraulic | | | | flow of water, this generates electrical impulses |
| pumps or rotary drives. GPS/Chart plotters can | | | | that are fed to a microprocessor that displays |
| be used to input navigational instructions to the | | | | both speed and distance run. |
| autopilot. | | | | Inverters - On most boats today you will find |
| Battery Chargers will keep batteries fully charged | | | | domestic equipment of one sort or another. For |
| thereby extending their working life. | | | | on board entertainment there are televisions and |
| Chart Plotters Typically a chart plotter consists of | | | | stereo systems. With the popularity of chart |
| an antenna, mounted high on the boat, to track | | | | plotters comes the PC or laptop. Maintenance |
| GPS signals and a display unit sited either at the | | | | often requires the use of power tools. |
| at the navigation station or the helm of the | | | | Liveaboards might have a washing machine, |
| vessel. The vessels position is sent from the | | | | dishwasher or microwave. Can take 12v, 24v or |
| antenna to the display unit which in turn shows it | | | | 48v supply and convert it to a stable 110 v or |
| graphically on the chart. The Chart itself will look | | | | 220v AC supply. |
| similar to it's paper equivalent and show depth, | | | | Navtex can perhaps best be described as a |
| land mass, navigational aids such as bouys and | | | | continuously updated telex service providing |
| potential dangers in the form of wrecks and | | | | navigation and weather information within specified |
| obstructions. The user can add way points to the | | | | areas. An on board receiver, tuned to 518kHz, the |
| chart and zoom in and out of the display. Chart | | | | worldwide Navtex frequency, if left turned on will |
| plotters can be connected to drive an autopilot | | | | either print out or display the latest massages |
| and/or send GPS data to a fish finder or radar. | | | | sent from a local station. The service is available |
| They can also interface with a laptop enabling | | | | up to 400 miles from the coast. |
| complex passage planning to be done away from | | | | Radar enables you to see what otherwise would |
| the boat and then entered into the chart plotter | | | | be invisible. They offer greatest benefit at night |
| after arriving at the boat. | | | | and in fog or rain and are of particular value when |
| Magnetic Transmitting Compasses work like | | | | close to shore or in busy shipping lanes. They |
| traditional compasses using magnets to determine | | | | consist of an antenna and a display. The antenna |
| the vessels orientation to the earth's magnetic | | | | sends out a stream of RF energy which is |
| field they then transmit the boats heading to an | | | | reflected back off hard objects. When this energy |
| electronic display. They make steering easier than | | | | is bounced back it is converted to a signal which |
| with conventional compasses because they display | | | | displayed to the user. The antenna rotates every |
| steadier headings and do not suffer from the "lag" | | | | few seconds, the display continuously calculates |
| that occurs when making a turn. They can | | | | the direction of the antenna and so a precise |
| interface with chart plotters, autopilots and radar. | | | | bearing to the target is calculated. The time is |
| Fluxgate Compasses consist of two pieces of | | | | measured for the energy to be reflected and so |
| readily saturated magnetic material with coils | | | | the distance of the target is also displayed. |
| wound round them in opposing directions. AC | | | | Satellite Phones consist of an antenna, a modem |
| current is passed through the coils and the | | | | and a normal handset. They are powered by an |
| material is saturated in one direction and then the | | | | iridium battery. Their range is anywhere covered |
| other. The earth's magnetic field affects slightly | | | | by in Inmarsat Mini-M satellite. Voice, fax, email |
| the time at which saturation occurs, earlier in one | | | | and data can be transmitted. |
| coil and later in the other. The difference is then | | | | Satellite TV requires an antenna and of course a |
| calculated giving an output proportional to the | | | | television. Reception is available within a "footprint" |
| earth's magnetic field. They are accurate to 0.1 of | | | | which is based on EIRP (Effective Isotropic |
| a degree. Their output can be displayed digitally to | | | | Radiated Power) of a transmitting satellite. The |
| the helmsman or they can interface with | | | | EUTELSAT together with the two ASTRA |
| autopilots, chart plotters and radar. | | | | satellites cover Europe. NILESAT and the two |
| Echo Sounders work on the same principle as | | | | ARABSATs cover Africa and the Middle East. |
| sonar. A transducer emits a narrow beam of | | | | Good coverage is also available in North, Central |
| high frequency sound. This is reflected by any | | | | and Southern America. |
| solid objects and the time between transmission | | | | SSB Radio has a range of several thousand miles. |
| and receipt of the echo is measured. The speed | | | | You will need an FFC license, or the equivalent in |
| of sound through water is know and so the range | | | | whichever country you plan to operate it. Power |
| or distance to the sea bed can be calculated. That | | | | consumption is a consideration. Up to 100 Watts |
| is then displayed in metres. Forward Looking | | | | may be required for transmission. SSB radio |
| Sonar (FLS) enables you to see the underwater | | | | requires several items of equipment. A |
| hazards before you're actually on top of them. A | | | | transceiver capable of SSB operation, An antenna, |
| typical range for a FLS is 150 metres. | | | | this must be 8 metres long and in practice most |
| An Emergency Position Indicating Radio Beacon | | | | boats use a backstay or shroud for the purpose |
| (EPIRB) is a piece of equipment designed to float | | | | having fitted the necessary insulators. An antenna |
| free of a vessel in distress. It then sends a radio | | | | tuner matched to the transceiver model. If you |
| signal that can be detected by Search and | | | | want to send email you will also need and radio |
| Rescue Satellite Aided Tracking (SARSAT) | | | | modem and computer. |
| satellites. They relay a message to a ground | | | | VHF Radio The power required to transmit is |
| station that in turn can instigate a search and | | | | minimal, all sets have the option of transmitting on |
| rescue operation. | | | | either 1 Watt or 25 Watts and the lower power |
| Fish Finders use the same technology as sonar. A | | | | should be used whenever possible. Unlike |
| narrow beam of high frequency sound is | | | | telephones that allow you to both talk and hear at |
| transmitted by a transducer, this is reflected by | | | | the same time most VHF sets require you to |
| solid objects such as the sea bed. By developing | | | | press a transmit button prior to talking. This is |
| this technology fishfinders provide displays that | | | | known as simplex. Duplex sets are available but |
| show where the fish are and they can | | | | are much more expensive. VHF radio waves |
| differentiate between bait fish and larger species | | | | travel in straight lines so the aerial should be |
| Global Positioning System (GPS Receivers) - This | | | | mounted as high as possible, preferably at the |
| system was originally designed for military | | | | masthead. |
| purposes and is owned and operated by the | | | | |