Electrical systems on ships and shipyards.

Assignment-I

Submitted by,

Group No.5 – Gopikrishnan S,

Goutham Venkatesh K,

Harsh Rohit,

Hisham Ibnu Hamza

Satellite NavigationThe idea that led to development of the satellite navigation systems dates back to 1957 and the first launch of an artificial satellite into orbit, Russia’s Sputnik I. Dr.William H. Guier and Dr. George C. Wieffenbach at the Applied Physics Laboratory of the Johns Hopkins University were monitoring the famous “beeps” transmitted by the passing satellite. They plotted the received signals at precise intervals, and noticed that a characteristic Doppler curve emerged. Since satellites generally follow fixed orbits, they reasoned that this curve could be used to describe the satellite’s orbit. They then demonstrated that they could determine all of the orbital parameters for a passing satellite by Doppler observation of a single pass from a single fixed station. The Doppler shift apparent while receiving a transmission from a passing satellite proved to be an effective measuring device for establishing the satellite orbit.

The Navy Navigation Satellite System (NAVSAT, also known as TRANSIT) was the first operational satellite navigation system. The system’s accuracy was better than 0.1 nautical mile anywhere in the world, though its availability was somewhat limited. It was used primarily for the navigation of surface ships and submarines, but it also had some applications in air navigation. It was also used in hydrographic surveying and geodetic position determination. The transit launch program ended in 1988 and the system was disestablished when the Global Positioning System became operational in 1996.

Principle of operation.

The satellites are launched into orbits which are as nearly as possible circular and polar, and at a height of approximately 1125 km. Each satellite orbits the earth in approximately one hundred and seven minutes, continuously transmitting a two minute message on each of two frequencies (150 MHz and 400 MHz). The message contains information which accurately defines the satellite’s orbit. To precisely determine its present and future orbits each satellite is tracked as it passes within ‘sight’ of each of the four tracking stations. Then for the following twelve to sixteen hour period, the specific position of the satellite at two-minute intervals is computed. This data along with time corrections, is passed to three injection stations. The injection stations store this information until the time of injection, when the antenna of the appropriate station locks-on to the satellite, and data is transmitted to it. The two minute transmission message of the satellite is then refreshed with the new orbital data.

Satellite system.

Global Positioning System Concepts

GPS measures distances between satellites in orbit and a receiver on Earth, and computes spheres of position from those distances. The intersections of those spheres of position then determine the receiver’s position.

The distance measurements described above are done by comparing timing signals generated simultaneously by the satellites’ and receiver’s internal clocks. These signals, characterized by a special wave form known as the pseudo-random code, are generated in phase with each other. The signal from the satellite arrives at the receiver following a time delay proportional to its distance traveled. This time delay is detected by the phase shift between the received pseudorandom code and the code generated by the receiver. Knowing the time required for the signal to reach the receiver from the satellite allows the receiver to calculate the distance from the satellite. The receiver, therefore, must be located on a sphere centered at the satellite with a radius equal to this distance measurement. The intersection of three spheres of position yields two possible points of receiver position. One of these points can

be disregarded since it is hundreds of miles from the surface of the Earth. Theoretically, then, only three time measurements are required to obtain a fix from GPS. In practice, however, a fourth measurement is required to obtain an accurate position from GPS. This is due to receiver clock error. Timing signals travel from the satellite to the receiver at the speed of light; even extremely slight timing errors between the clocks on the satellite and in the receiver will lead to tremendous range errors. The satellite’s atomic clock is accurate to 10 -9 seconds; installing a clock that accurate on a receiver would make the receiver prohibitively expensive. Therefore, receiver clock accuracy is sacrificed, and an additional satellite timing measurement is made. The fix error caused by the inaccuracies in the receiver clock is reduced by simultaneously subtracting a constant timing error from four satellite timing measurements until a pinpoint fix is reached.

Assuming that the satellite clocks are perfectly synchronized and the receiver clock’s error is constant, the subtraction of that constant error from the resulting distance determinations will reduce the fix error until a “pinpoint” position is obtained. It is important to note here that the number of lines of position required to employ this technique is a function of the number of lines of position required to obtain a fix. GPS determines position in three dimensions; the presence of receiver clock error adds an additional unknown. Therefore, four timing measurements are required to solve for the resulting four unknowns.

References.

Marine Electronic Navigation- S.F.Appleyard

Pdf on Satellite navigation by National Geospatial-Intelligence Agency, USA

External communication equipment

Satellite Communication In 1962, the American telecommunications giant AT&T launched the world's first true communications satellite, called Telstar. Since then, countless communications satellites have been placed into earth orbit, and the technology being applied to them is forever growing in sophistication. Communication satellites are orbiting relays which receive, amplify, process, and retransmit signals from one point to another point on the surface of the Earth. Communication satellites have been in use since the 1960s for providing wideband global connectivity and long-range circuits of high quality virtually unencumbered by propagation difficulties. A satellite provides coverage within its footprint that is the area from which it is visible.

In the maritime community, satellite communication systems such as Inmarsat provide good communication links to ships at sea. These links use a VSAT type device to connect to geosynchronous satellites, which in turn link the ship to a land based point of presence to the respective nation’s telecommunications system. With the overcrowding of the hf spectrum, the need for new and advanced long-range communications became apparent. Satellite communications (SATCOM) systems have shown they can provide survivable, reliable, high-capacity, secure, and cost-effective telecommunications for the military.

Diagram- Satellite communications system.

Functional block diagram.

Principle of operation.

The communications systems use satellites that are either geostationary or orbiting. With a geostationary system the satellite remains in a fixed position relative to a given geographical location (the satellite is actually in a fixed orbit and moves in a consistent relationship to the Earth). With this type of system the satellite can, at all times, receive and transmit messages to any transmitter or transceiver that is within the fixed geographical area visible to the satellite. A communications system based on geostationary satellites may have more than one satellite to cover a greater percentage of the Earth’s surface.

An orbiting communications satellite moves in an orbit so that it passes above a given geographical location at periodic time intervals. Such a system means that earth bound transmitters or transceivers come into the satellite’s range at these periodic time intervals and transmit or receive only while the satellite is in range or “visible”. The transmitter may store messages until the satellite is in range. When messages are transmitted to the satellite, they may also be stored in the satellite until the satellite comes into range of a receiving earth station. Unlike a geostationary system, a single satellite can feasibly cover the whole of the Earth’s surface. However, there will be time gaps in coverage when the satellite is not in view of given geographical locations. Increasing the number of satellites will increase the coverage of the system by decreasing the time gaps when a satellite is not in view of a given location.

In both types of system a fixed or mobile transmitter can be used. Such a transmitter is mounted on a vessel, aircraft, building etc. and uses a radio signal to send a message to the satellite mounted transponder. The message can be stored in the satellite for later forwarding or immediately forwarded to a receiver or transmitter with a receiving capability (transceiver) mounted on another vessel, aircraft, building etc. In some cases the receiving station will be a large fixed station (an “earth station”) which will link to the normal terrestrial telephone system.

Purpose of use/Applications.

One important aspect of the satellite communications network is that it continues in operation under conditions that sometimes render other methods of communications inoperable. Because of this, satellites make a significant contribution to improved reliability of Navy communications. Satellite communications have unique advantages over conventional long distance transmissions. Satellite links are unaffected by the propagation variations that interfere with hf radio. They are also free from the high attenuation of wire or cable facilities and are capable of spanning long distances. The numerous repeater stations required for line-of-sight are no longer needed. They

furnish the reliability and flexibility of service that is needed to support a military operation.

Telephony

The first and still, arguably, most important application for communication satellites is in international telephony. Mobile telephones (to and from ships) must be directly connected to equipment to uplink the signal to the satellite, as well as being able to ensure satellite pointing in the presence of disturbances, such as waves onboard a ship.

Television and Radio

There are two types of satellites used for television and radio:

Direct Broadcast Satellite (DBS): DBS is a term used to refer to satellite television broadcasts intended for home reception, also referred to as direct-to-home signals. It covers both analogue and digital television and radio reception, and is often extended to other services provided by modern digital television systems, including video-on-demand and interactive features.

Fixed Service Satellite (FSS): FSS is the official classification for geostationary communications satellites used chiefly for broadcast feeds for television and radio stations and networks, as well as for telephony, data communications, and also for Direct-To-Home (DTH) cable and satellite TV channels. 

Mobile Satellite Technology.Initially available for broadcast to stationary TV receivers, popular mobile direct broadcast applications made their appearance with that arrival of two satellite radio systems: Sirius and XM Satellite Radio Holdings. Some manufacturers have also introduced special antennas for mobile reception of DBS television. Using GPS technology as a reference, these antennas automatically re-aim to the satellite no matter where or how the vehicle (that the antenna is mounted on) is situated.

Amateur radio.

Amateur operators have access to the OSCAR satellites that have been designed specifically to carry amateur radio traffic. Most such satellites operate as space borne repeaters, and are generally accessed by amateurs equipped with UHF or VHF radio equipment and highly directional antennas such as Yagis or dish antennas. Due to the limitations of ground-based amateur equipment, most amateur satellites are launched into fairly low Earth orbits, and are designed to deal with only a limited number of brief contacts at any given time. 

Satellite Broadband

.In recent years, satellite communication technology has been used as a means to connect to the internet via broadband data connections. This is very useful for users to test who are located in very remote areas, and can't access a wireline broadband or dialup connection.

Role of satellite communications

SATCOM links, one of several kinds of long distance communications links, interconnect communications centres located strategically throughout the world. These SATCOM links are part of the Defence Satellite Communications System (DSCS) and Fleet Satellite Communications. Satellite communications systems are very important to the worldwide military communications network for two primary reasons. First, they continue to operate under conditions that cause problems for other methods of communication. Second, they provide reliable and secure communications to previously inaccessible areas.

In many cases, these communications requirements can only be satisfied by sophisticated satellite communications systems. By satisfying such needs, SATCOM makes a significant contribution to the improved reliability of naval communications.

Advantages of satellite communications

Some of the unique advantages SATCOM has over conventional long-distance communications are as follows:

SATCOM links are unaffected by the propagation problems associated with hf radio communications.

SATCOM links are free from the high attenuation problems of facilities that use wire or cable for routing communications.

SATCOM links span long distances.

The numerous repeater stations required for line-of-sight and troposcatter systems are not needed.

Satellite links provide the required flexibility and reliability needed to support military operations

Capacity

Currently, military SATCOM systems can provide communications between backpack, shore, airborne, and shipboard terminals. These SATCOM systems can handle thousands

of communications channels at the same time.

Reliability

SATCOM frequencies are only slightly affected by atmospheric phenomena and do not depend on reflection or refraction. Reliability is based on the skill of operators and maintenance personnel and the condition of the satellite communications equipment.

Vulnerability

Communications satellites are relatively safe from threats of harm. Because these satellites are in such high orbits, any attempt to disable or destroy them from the Earth would be difficult and expensive. However, Earth terminals are a different story. They offer a more attractive target for destruction by conventional methods. But these terminals can be protected by the same methods taken to protect other vital installations. So overall, the satellite system is nearly free from harm by an enemy. Operationally, highly directional earth terminal antennas provide a high degree of freedom from jamming. The wideband system can use ant jamming techniques, which also reduces vulnerability.

Flexibility

Mobile military satellite earth terminals with trained crews can be deployed and put into operation anywhere in the world within hours.

Limitations

The technical characteristics of the satellite and its orbital parameters are the main limitations to a satellite communications system. Two additional limiting factors for active satellites are transmitter power and receiver sensitivity. Energy for electricity is limited to whatever can be produced by the solar cells, which limits the satellite’s output power. This problem is made worse by users who increase their output power to the satellite, causing the satellite to try to retransmit at the new power level, at the expense of reducing signals to other users.

References

wikipedia.com

marineinsight.com

Role of Satellite communications- electriciantraining.tpub.com

Satellite applications- Encyclopedia Britannica

Naval Shipboard Communications Systems- John C. Kim, Eugen I. Muehldorf

VHF Radio

Marine VHF radio refers to the radio frequency range between 156.0 and 162.025 MHz, inclusive. In the official language of the ITU the band is called the VHF maritime mobile band.

It's installed on all large ships and most seagoing small craft. It is also used, with slightly different regulation, on rivers and lakes. It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours, locks, bridges and marinas, and operates in the very high frequency (VHF) range, between 156 and 162.025 MHz. Although it is widely used for collision avoidance, its use for that purpose is contentious and is strongly discouraged by some countries, including the UK.

Diagram

vhf set and vhf channel.

standard handheld maritime vhf.

Block diagram -Vhf transmit and receive system .

Principle of operation

A marine VHF set is a combined transmitter and receiver and only operates on standard, international frequencies known as channels. Channel 16 (156.8 MHz) is the international calling and distress channel. Transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60 nautical miles (111 km) between aerials mounted on tall ships and hills, and 5 nautical miles (9 km; 6 mi) between aerials mounted on small boats at sea level.[1] Frequency modulation (FM) is used, with vertical polarization, meaning that antennas have to be vertical in order to have good reception.

Marine VHF mostly uses "simplex" transmission, where communication can only take place in one direction at a time. A transmit button on the set or microphone determines whether it is operating as a transmitter or a receiver. The majority of channels, however, are set aside as "semi-duplex" transmission channels where communication can take place in both directions

simultaneously.[1] Each semi-duplex channel has two frequency assignments. Semi-Duplex channels can be used to place calls on the public telephone system for a fee via a marine operator. Sets can be fixed or portable. A fixed set generally has the advantages of a more reliable power source, higher transmit power, a larger and more effective aerial and a bigger display and buttons. A portable set (often essentially a waterproof, VHF walkie-talkie in design) can be carried on a kayak, or to a lifeboat in an emergency, has its own power source and is waterproof if GMDSS-approved. A few portable VHFs are even approved to be used as emergency radios in environments requiring intrinsically safe equipment (e.g. gas tankers, oil rigs, etc).

Vhf Transmit

A typical vhf transmit and receive system is shown in the block diagram. On the transmit side, the operator, at a remote location, talks into the handset. The handset is connected to radio set control, C-1138. The radio set control output is fed to transmitter transfer switchboard, SB-988/SRT. The switchboard performs the same function as it does in the lf and hf systems. The output of the switchboard is connected to the transmit side of the transmitter/receiver (transceiver), AN/VRC-46 or AN/VRC-80. The transceiver converts the input signal to an rf signal for transmission and the rf is radiated into the atmosphere by the antenna.

Vhf Receive

In the diagram, the incoming signal is picked up by the antenna. This signal is fed to the receive side of the transceiver. The transceiver output is fed to the receiver transfer switchboard. The switchboard output is connected to either radio set control or to a speaker amplifier, AM-3729, or both, depending on the user’s preference. The output of the radio set control is fed to the handset and the speaker amplifier output is routed to the speaker.

Purpose of use

Marine VHF Radios are two-way communicators which are used to transfer and receive messages. However, the most important function of a Marine VHF Radio is that it is very helpful when it comes to sending distress signals across the channels to coast guards and other ships and boats in the periphery. Also, certain Marine VHF Radios can be used for the purposes of making calls through a marine operator for a certain sum making it double up as a telephonic communicator too. Another important aspect of Marine VHF Radios is the fact that they come in two main categories: portable ones and non-portable ones. The portable ones have waterproof coverings and are battery operated in order to facilitate the power transmission. The fixed or the non-portable Marine VHF Radios cover a lot of aerial ground, their source of power transmission and energy, huger in comparison to their portable counterparts and are therefore far more feasible in terms of their operational facilities.

 It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours, locks, bridges and marinas, and operates in the very high frequency (VHF) range, between 156 and 162.025 MHz. Although it is widely used for collision avoidance, its use for that purpose is contentious and is strongly discouraged by some countries.

References

Marine VHF Radio- Wikipedia.

marineinsight.com

Communications system pdf- US Navy education and training center.

Ship’s service telephone system The Ship’s Service Telephone Circuit (J-Dial) requires an external electrical power source and has a keypad just like a home phone.

When installed, it may be used as an alternate means of communication. The J-Dial system shouldn’t be relied upon because it is not as rugged as the sound-powered phone system and may go out of commission early in action. Some of the newer systems have a limited battery backup in the event of a loss of electrical power. On some ships, the J-Dial phones are available for damage control communications when located near or at repair stations and may be used when other damage control communication systems are inoperative.

Although the ship’s service telephones are not part of the battle communication system, they can prove invaluable if the regular systems fail. They are standard telephones powered by the ship’s generators and are normally used in carrying out the administrative routine aboard ship. Two features expedite the telephone-calling process: the executive cut-in telephone and the hunt-the-not-busy-line feature. Executive cut-in telephones, clearly marked, are for emergency calls and for the use of persons in authority. Operationally, these telephones are the same as a standard telephone but are limited in number and can be used to call a station that is in use. Instead of a busy signal being returned, the cut-in phone breaks into the circuit. The caller then can interrupt the conversation in progress to deliver an important message. The hunt-the-not-busy-line feature can be used when a call is made to an area that has a group of consecutively numbered telephone stations. After the lowest numbered station has been dialed, the switchboard connects the calling station to the lowest numbered idle telephone. When all the circuits of the group called are in use, a busy signal is returned as with a standard telephone

Image- Ship’s service telephone

Radiotelephone

Radiotelephone is one of the most useful military communications methods. Radiotelephone equipment for tactical use usually is operated on frequencies that are high enough to have line-of-sight characteristics; that is, the waves do

not follow the curvature of the earth. As you know, these characteristics limit the usual range of radiotelephone from 20 to 25 miles. This is important because it reduces the chances of the enemy intercepting the message. Radiotelephone procedures can be learned easily by persons with no other training in communications.

The Marine Radiotelephone Service or HF ship-to-shore operates on shortwave radio frequencies, using single-sideband modulation. The usual method is that a ship calls a shore station, and the shore station's marine operator connects the caller to the public switched telephone network. This service is retained for safety reasons, but in practice has been made obsolete by satellite telephones (particularly INMARSAT) and VoIP telephone and email via satellite internet.

Short wave radio is used because it bounces between the ionosphere and the ground, giving a modest 1,000 watt transmitter (the standard power) a world-wide range. Most shore stations monitor several frequencies. The frequencies with the longest range are usually near 20 MHz, but the ionospheric weather (propagation) can dramatically change which frequencies work best.

Single-sideband (SSB) is used because the short wave bands are crowded with many users, and SSB permits a single voice channel to use a narrower range of radio frequencies (bandwidth), about 3.5 kHz. In comparison, AM radio uses about 8 kHz, and narrowband (voice or communication-quality) FM uses 9 kHz. Marine radiotelephony first became common in the 1930s, and was used extensively for communications to ships and aircraft over water. In that time, most long-range aircraft had long-wire antennas that would be let out during a call, and reeled-in afterward.

Radiotelephone has some disadvantages. You may find transmissions unreadable because of static, enemy interference, or high local noise level caused by shouts, gunfire, and bomb or shell bursts. Wave propagation characteristics of radiotelephone frequencies sometimes are unpredictable, and tactical transmissions may be heard from great distances. Most radiotelephone messages are in plain language, and if information is to be kept from the enemy, users must keep their messages short, stick to the proper procedures, and be careful of what they say.

Purpose of use

The ship’s service telephones are not part of the battle communication system, they can prove invaluable if the regular systems fail.

The radiotelephone, because of its directness, convenience, and ease of operation, is used by ships, aircraft, and shore stations. It has many applications and is used for ship-to-shore, shore-to-ship, ship-to-ship, air-to-ship, ship-to-air, air-to-ground, and ground-to-air communications. Modern means of operation make it possible to communicate around the world by radiotelephone. One of the most important uses of radiotelephone is short-range tactical communications. This method permits tactical commanders to communicate directly with other ships. Little delay results while a message is prepared for transmission, and acknowledgments can be returned instantly. One of the most important uses of marine radiotelephony has been to change ships' itineraries, and to perform other business at sea.

References

Pdf on “Introduction to radio-frequency communications” by US Navy.

Teletypewriter A teletypewriter (TTY; also called a teletype or teleprinter) is a device that sends a typed message to another place. A teletypewriter has

a typewriter keyboard, a local printer (so the user can see what has been typed) and a transmitter. Messages can be sent over wires or radio waves. Teletypes were used mostly in the early to mid-20th century. They were developed to improve telegraphs, some of which also used keyboards, though not typewriter keyboards.Teletypewriter (tty) signals may be transmitted by either landline (wire), cable, or radio. The landline tty is used both by the military services and by commercial communication companies. The Navy uses radio teletypewriter (rtty) mainly for high-speed automatic communications across ocean areas. The tty unit is equipped with a keyboard similar to a typewriter. When the operator presses a key, a sequence of signals is transmitted. At receiving stations, the signals are fed into terminal equipment that translates the sequences of signals into letters, figures, and symbols and types the messages automatically.

The rtty mode of transmission and reception is rapidly becoming more efficient and reliable for communications between ships and from ship-to-shore. Ships copy what is known as "fleet broadcast" messages on rtty. The speed at which message traffic is transmitted on rtty circuits depends on the equipment in use. Normal speed of operation is 100 words per minute, but it may be faster or slower. You may find high-speed equipment, capable of printing a line or even a page at a time, in some communications centers. The use of rtty has brought about a considerable savings in manpower.

Radio-teletypewriters in use aboard Adirondack (AGC-15) circa 1946

Block diagram of teletype system.

Purpose of use

Modes of operation

There are two basic modes of teletypewriter operation: asynchronous (start-stop) and synchronous. The asynchronous mode is the most common. The synchronous mode is used primarily in high-speed datasystems.

>Asynchronous Mode

In this mode, the receiving device is only allowed to run for one character and is then stopped to await the start signal for the next character. Any differences in speed between the transmitting and receiving device scan only accumulate during the time assigned to one character. There is a penalty for this advantage. Character length is increased to include the start (space) and stop (mark) signals. These start and stop signals are part of the five unit code (BAUDOTCODE).

>Synchronous Mode

Synchronous systems have an advantage over asynchronous systems. The start and stop elements are not used. This allows more room for information transmission. Time is not wasted on start and stop units. Additionally, this mode has a higher capacity to accept distorted signals because it does not depend on the start and stop signals for timing.

References

Pdf on “Introduction to radio-frequency communications” by US Navy.

TelexThe telex network is a switched network of teleprinters similar to a telephone network, for the purposes of sending text-based messages. The term refers to the network, not the teleprinters; point-to-point teleprinter systems had been in use long before telex exchanges were formed starting in the 1930s. Teleprinters evolved from telegraph systems, and like the telegraph they used the presence or absence of a pre-defined level of current to represent the mark or space symbols. This is as opposed to the analog telephone system, which used differing voltages to encode frequency information. For this reason, telex exchanges were entirely separate from the telephone system, with their own signaling standards, exchanges and system of "telex numbers" (the counterpart of a telephone number). When telephone and telex exchange equipment was co-located, which was not uncommon, the different signalling systems would sometimes cause interference.

A Teletype Model 32 used for Telex service.

siemens T-100 Telex machine.

Telex is still in operation, but has been mostly superseded by fax, email, and SWIFT, although radiotelex, telex via HF radio, is still used in the maritime industry and is a required element of the Global Maritime Distress and Safety System (GMDSS).

Purpose of Use

Navtex (Navigational Telex) provides a cheap and accurate means of receiving all safety related information closer to the coast. It is automatic, user friendly and does not involve regular monitoring. An officer has to just switch it on and initialize it and the receiver will print (or store, as in some models) MSI information automatically.

The Navtex is the most convenient way of monitoring navigational warnings, meteorological warnings, search and rescue information and other data for ships sailing within 300 miles of shore.

References

Telex- Wikipedia.com

brighthubengineering.com

e-mail/Internet

E-mail is a very useful and handy means of communication. The most common mode of

providing internet on ships is through satellite. Providing a direct connection with the

satellite services through some hardware installations on the ship, easy access to internet

can be provided for all the on boarders. The hardware installations are a must so that

internet signals can be tapped from anywhere. The choice of hardware depends on number

of factors like

- Ship size

- Intended internet usage

- Speed desired

- Cost component

A lot of companies offer a wide range of such devices which can help you find just what you

need. But it is more like one time investment allowing easy internet access thereon. Even

on cruise ships, there are specific zones that offer internet connections for their

passengers, allowing them to access their email from any part of the world, literally. Some

ships also have marked Wi-Fi zones that offer wireless internet usage for all.

References

Marineinsight.com

Situations Wherein Engine and Deck Officers Must Maintain Efficient Communication

>Engine Room Machinery Abnormality: A machinery in the ship’s engine room is bound to face problem when at sea. In case of breakdown of any machinery, the duty engineer must inform the bridge officer immediately without any delay. If problem occurs in the main engine, power generator or any associated machinery which can affect the voyage of the ship, the engineer must take all necessary steps and inform the bridge at the earliest.

> Fire on ship: With implementation of advanced safety and automation systems, detection of fire on board ships has become quite efficient. In case of fire on the ship, the indication of affected location is displayed either on the bridge or in the fire station. In such condition, it is important that deck officer call the engine room to inform about the specific location of fire even after the fire alarm has been sounded. The same rule also applies to the engine officer, who must inform the bridge on how big is the fire and its condition after ringing the fire alarm. However, only informing is not important, it is necessary that all required steps are taken by the ship’s crew to stop the fire and inform other department regarding the same.

> Fog, Traffic or Other Manned Situation: Today, most of the ships have UMS engine room and the engine is controlled from the bridge. If any situation arises wherein the engine is to be slowed down and manned, the bridge officer must inform the duty engineer well in advance. These situation may include: Fog or weather warnings, Canal Crossing, High Traffic Areas, Under-Bridge Crossing etc.

> Heavy Smoke/ Spark from the Funnel: If the ship’s funnel is discharging abnormal black/ white smoke or there are sparks rising from the funnel, the deck officer on the bridge must inform the same to the engine room immediately as it may lead to uptake fire if ignored.

>Internal Oil Transfer Operation: Any engine room internal oil transfer procedure must be pre-informed to the bridge officer as the transfer of oil from one tank to another may affect the current list/ trim of the ship. Also, an informed deck officer will keep a good overboard watch and revert back to the engine room immediately in case of oil leakage or spill.

> Pumping Operation: Ballast pumps are high capacity pumps which are used to correct the list, trim or draught of the ship. They are also used in ports for cargo loading/ discharging. In order to save fuel, normally one generator is run at higher load when the ship is at port. Hence deck officer must inform the engine department before starting any pumps including ballast and fire pump as there might be a requirement to start one more generators to accommodate the power requirement.

> Deck Machinery Operation: Before starting any deck machinery including bow thrusters and winches, the deck officer must inform the engine department so that engineers can check and ensure that the machinery is ready to start and the generator has enough accommodating power available. Also, in case of bow thruster (BT), hydraulic pumps and fans are to be started sequentially before the main operation, which the ship engineer will perform if informed well in advance.

> OWS Operation: Nowadays, Oily Water Separator is an important ship machinery checked by all PSCs on every visit. It is important for marine engineers to inform the bridge and take position of the ship while starting and stopping the Oily Water Separator (OWS). Also, bridge officers are required to take a note of the same in the bridge log book. An overside check is also required by the bridge officer for any oil sheen in water once the OWS operation has started. Oil pollution from ships is a serious crime which includes huge fines and even imprisonment. OWS operation therefore requires clear and sound communication between officers from both the departments.

> Manning / Un-manning the Engine Room: Engine officer on duty of a UMS ship must inform the bridge before turning on the Unmanned mode and leaving the engine room. Engineer should inform about his visit and manned/unmanned situation every time he/she visits the engine room and switch on or switch off the dead man’s alarm. This will help in informing the bridge officer of an engineer’s presence in the machinery space. Also, in case of any mishap in the engine room or “no reply” of the dead man’s alarm, the deck officer can assist and take imPilot/ PSC Onboard: It is the duty of the bridge officer to inform the engine room about the pilot boarding time or whenever any outside authority is about to visit the ship. This will give time to engine room staff to be ready for important situations and prevent any kind of ship delay.

Running a ship safely and efficiently is a team-effort which requires utmost clear communication between the deck and engine officers. The above mentioned situations are some of the most important ones which needs great coordination between both the ship departmentsmediate action.