Icebreakers are to clear the way through the stratums of ice in the seas which are adjacent to the Earth’s poles.

Dredgers are to remove the sand and mud from the beds of channels and harbors.

Lightship is an anchored ship without engines but with a lights, a foghorn, a radio beacon and meteorological equipment.

Pilot launches are motorboats for transporting pilot to and from the ships.

Oceanographic ships are to carry scientists with instruments across the sea to study something new about it.

Fishing vessels aren’t only to catch fish but even to process them.

5. 6. During the voyage the weather can change many times so it’s highly important to know all weather conditions, to predict any weather changes, and assume measures in advance. To make accurate weather forecast, you should have any necessary instruments.

Weather is the momentary, day-to-day state of the atmosphere over any place on the Earth’s surface.

The weather consists of such factor as wind speed, relative humidity, atmospheric pressure, air temperature, wave’s force. Thermometers measure air temperature. They work because the matter expands when heated. Most thermometers are closed glass tubes containing liquids such as alcohol. When air around the tube heats the liquid, the liquid expands and moves up the tube. A scale that shows the temperature is attached to the tube.

A barometer measures air pressure. Inside the barometer you can find a cylinder what reacts to the atmosphere pressure. If pressure ascends the cylinder shrinks, and conversely. The cylinder is attached to the spring, which moves an arrow on the scale. The scale tells us the exact air pressure.

A psychrometer measures relative humidity, using the cooling effect of evaporation. Two thermometers are used in a psychrometer. A wet cloth covers the end of one of the thermometers. Water evaporates from this cloth, causing the temperature on that thermometer to be lower than the other. Using the difference between the results of both thermometers and special table man can tell relative humidity.

An anemometer measures wind speed. It looks like a stick with a cross with cups attached to the top of the stick. The cups catch the wind, turning the dial attached to the instrument. The dial shows the wind speed.

Weather balloons measure weather conditions higher in the atmosphere.

Weather satellites are able to photograph and track large – scale air movements. Then meteorologists compile and analyze the data with the help of computers.

7. Communications at sea are essential for efficient and safe running of a ship. They take place within the ship herself, between the ship and other ships, between the ship and shore stations and sometimes between the ship and aircraft. Communications can be made over different distances and using methods ranging from the simplest to those using the most sophisticated radio technology.

One of the oldest methods of remote communication still exists today. One writes a message on a piece of paper and has is delivered to the recipient. At sea you can receive written messages at ports where the vessel stopped or from vessels encountered along the way. In some cases, it could take months or even years for a message to reach the addressee.

Message can be sent with use of signal flags and semaphore to anyone who can see and understand it. Even today most large ships and many smaller ones carry signal flags aboard. Since these messages were visible to everyone nearby, elaborate codes were developed to identify the sender and recipient and to hide the meaning of the message. The flags used for signaling are known as pennants. Each pennant may represent a letter of the alphabet, or a number, allowing complete words to be spelled , or it may signal one of the codes according to the International Code of Signals. This code was developed to allow boats to communicate with each other even if they don`t know each other`s language. The International Code of Signals covers such things as maneuvering ships, towing, emergencies, medical problems and much more. In 1837 F. B. Morse developed one of the first practical telegraphs and also designed a code for it, in which different combinations of dots and lashes represented the letters of the alphabet. Morse code was very useful for mariners. The signals were sent using the heliograph producing sequence of long and short flashes corresponding dots and lashes.

Today communication can be done using radio equipment. There are two basic types of radios used aboard. Marine VHF (very high frequency) radios require an uninterrupted line of sight between antennas. They are usually used to communicate over small distances. Second type is SSB (single side-band) radio. It has much greater range than VHF, but consumes a much more electricity.

Satellite communication is used for long-distance communication. Digital signal from the ship is transmitted to the satellite, which when relays the signal to another satellite or to a receiver on the Earth`s surface. Satellite communication is private and allows direct access to global communication infrastructure (telephone and computer networks), also satellite communication is not greatly affected by meteorological conditions.

Communications within the ship are done by an internal telephone system. Communications over relatively short distances can be done by visual or sound signals. Visual signals can be sent by using Aldis lamp, which can produce flashing messages in Morse Code. Sound signals can be made with the ship`s siren, whistle or bell. In emergencies rockets and flares are used to signal distress and acknowledge such signals.

8. There are three main sources of the pollution at sea: collision, fire or grounding which results in the release of oil from the ship`s tanks; intentional discharge of oil and oily waste from the pumping of the bilges, or deballasting the cargo tanks, or tank washings; accidental spills while transferring fuel or cargo from ship to ship, or from ship to shore, an accidental spillage resulting from the incorrect operation of valves on shipboard or at oil terminals. Reasonable precautions should be taken to minimize or prevent the pollution.

In case of an oil spill the Master should immediately notify and consult the local Protection & Indemnity representative. The Master should ensure that steps are taken to clear up the spill and prevent further damage. The P & I representative will make arrangements for legal representation and attendance of surveyors if necessary.

Action taken to prevent stowaways from boarding a ship can be divided in several groups: actions to be taken prior to arrival in port, actions to be taken when at anchor, actions to be taken when in port and pre-sailing actions.

Before ships arrive in port the crew must ensure that all permanent deck lighting is fully operational, because well-lit vessel will deter potential stowaways. Also all areas which are not essential for loading and discharge of cargo should be carefully secured.

While staying at anchor it is important to secure all means of access, including hawser-pipe covers and covers on anchor chains. Moreover, all gangways and accommodation ladders should be raised when not in use. A proper watch should be kept at all times – regular deck patrols should be made by crew members working in pairs.

During the mooring in port it is essential that information concerning the vessel`s future ports of call is restricted. There should be positive restriction and control of movement of shoreside personell on board. It is important to keep a check on the number of gangs on board and the number of stevedors in each gang. An efficient gangway watch should be maintained all times. Each and every individual should be questioned to verify his right to board the ship. Access to accommodation areas should be restricted. Only essential accesses should remain open and unlocked and regular check should be made of all accommodation areas. All areas which are not essential for loading and discharge of cargo should be secured and locked and regular inspections should be taken.

Immediately prior to a vessel`s departure from port, it is important to conduct a thorough and extensive search using the manual checklist. The checklist recommends dividing the vessel into four zones, which should be systematically searched at the same time. After each area has been searched, this should be confirmed by radio, allowing the appointed officer to compile the checklist. Upon the completion of the checklist, an entry should be made in the deck logbook, recording the time, date and names of the individuals who have conducted the search. If, despite all your precautions, you find uninvited guests aboard your vessel, you should form a positive plan of action, following the owner`s standing instructions.

8. Ships must obey rules of the sea, which are designed to prevent collisions. These rules specify what action shall be taken by each of two approaching ships. They also prescribe the lights and sound signals to be used in various circumstances. To avoid the risk of collision at sea, all mariners abide by the “International Rules for Prevention Collision at Sea”.

Ships carry lights not as an aid to vision, but to allow them to be noticed by other mariners at night.

Ship’s lights are therefore arranged at specific angles and are displayed to give the experienced navigator all the information he needs.

A ship is required to carry five lights: a red light on the port side, and a green light on the starboard side, then identical while lights on the foremast and aftermast, the fifth light is a white light on the stern.

Safety standards for ships have been set up by International Safety of Life at Sea conventions. The standards require that ships have watertight bulkheads; fire-fighting equipment; and enough lifeboats, life jackets, and other lifesaving equipment. Other rules provide that lifesaving and fire drills must be carried out at regular intervals. Ships must follow the International Rules of the Road. These rules deal with such points as the rights of way of ships on the high seas, the lights ships must show, and the signals that ships must give in fog and during times or distress.