CONTROLLABLE PITCH PROPELLER

                                      

A controllable pitch propeller (CPP) or variable pitch propeller is a special type of propeller with blades that can be rotated around their long axis to change their pitch. If the pitch can be set to negative values, the reversible propeller can also create reverse thrust for braking or going backwards without the need of changing the direction of shaft revolutions.
Controllable pitch propellers (CPP) for marine propulsion systems have been designed to give the highest propulsive efficiency for any speed and load condition. When the vessel is fully loaded with cargo the propulsion required at a given ship speed is much higher than when the vessel is empty. By adjusting the blade pitch, the optimum efficiency can be obtained and fuel can be saved. Also, the controllable pitch propeller has a "vane"-stance, which is useful with combined sailing / motor vessels as this stance gives the least water resistance when not using the propeller (eg when the sails are used instead).

While it is true that a fixed pitch propeller (FPP) can be more efficient than a controllable pitch propeller, it can only be so at one rotational speed and the designed load condition. At that one rotational speed and load, it is able to absorb all the power that the engine can produce. At any other rotational speed, or any other vessel loading, the FPP cannot, either being over pitched or under pitched. A correctly sized controllable pitch propeller can be efficient for a wide range of rotational speeds, since pitch can be adjusted to absorb all the power that the engine is capable of producing at nearly any rotational speed.

The CPP also improves maneuverability of a vessel. When maneuvering the vessel the advantage of the CPP is the fast change of propulsion direction. The direction of thrust can be changed without slowing down the propeller and depending on the size of the CPP can be changed in approximately 15 to 40 seconds. The increased maneuverability can eliminate the need for docking tugs while berthing.

A reversing gear or a reversible engine is not necessary anymore, saving money to install and service these components. Depending on the main engine rotational speed and the size of the CPP, a reduction gear may still be required. A CPP does require a hydraulic system to control the position of the blades. A CPP does not produce more or less wear or stress on the propeller shaft or propulsion engine than an FPP. Therefore this will not be an argument to choose between an FPP or a CPP.

Most ships that wouldn't take a CPP are large vessels that make long trips at a constant service speed, for example crude oil tankers or the largest container ships which have so much power that a CPP is not yet designed for them. A CPP can mostly be found on harbor or ocean-going tugs, dredgers, cruise ships, ferries and cargo vessels that sail to ports with limited or no tug assistance.

Source: Indonesian-marine-engineer

LIST VOCABULARY

1.      Controllable   (Adj)               : Dapat dikontrol

2.      Propeller (Noun))                  : Baling-baling

3.      Propulsion (Noun)                 : Daya pendorong

4.      Ship (  Noun)                          :Kapal

5.      Pitch (Verb)                            : Melontarkan

6.      Vane                                       : Baling-baling

7.      Slowing                                   : Memperlambat

8.      Approximately                       : Sekitar

9.      Speed (Adj)                           : kecepatan

10.  Crude                                     : Mentah

11.   Reversible ( Adj)                  : Dapat dibalik

A.    ANSWER  THE QUESTION BELOW BASED ON THE TEXT

1.      What is a controllable pitch propeller (CPP) or variable pitch propeller?

2.      What is the aim by designing marine propulsion system?

3.      “it can only be so at one rotational speed and the designed load condition.” The word “it” refer to?

4.      What is the causal factor of a reduction gear?

5.      Where can A CPP mostly be found on?

B.     TRUE OR FALSE

NO.	SENTENCES	TRUE	FALSE
1	The reversible propeller can also create reverse thrust for braking or going backwards wit the need of changing the direction of shaft revolutions.	......	.......
2	When the vessel is fully loaded with cargo the propulsion required at a given ship speed is much higher than when the vessel is full.	......	......
3	A reversing gear or a reversible engine is not necessary anymore, wasting money to install and service these components.	......	......
4	A CPP produce more or less wear or stress on the propeller shaft or propulsion engine than an FPP.	......	......
5	The CPP also reduce maneuverability of a vessel.	.......	......

Ship-handling

                                                               SHIP  HANDLING

                                                                   

A fundamental skill of professional seamanship is being able to maneuver a vessel with accuracy and precision. Unlike vehicles on land, a ship afloat is subject to the movements of the air around it and the water in which it floats. Another complicating factor is the mass of a ship that has to be accounted for when stopping and starting.

Ship-handling is about arriving and departing a berth or buoy, maneuvering in confined channels and harbours and in proximity to other ships, whilst at all times navigating safely. Two other types of operations, berthing alongside another ship and replenishment at sea, are occasionally included. A key ability for a ship-handler is an innate understanding of how the wind, tide and swell, the passage of other vessels, as well as the shape of the seabed, will affect a vessel's movement, which, together with an understanding of a specific vessels performance, should allow that vessel a safe pa

Source: Wikipedia 

List of Vocabulary

      Vessel                   : Kapal

       Buoy                    : Pelampung

       Propeller              : Baling-Baling

       Astern                  : Dibelakang

       Rug                      : Sentakan

    Precision               : Kecermatan

Question

A. Read the text above and answer the question below!

               What should the professional seamanship do?

               How does important the Ship-handling?

               What is the key of ship-handler on the ship or vessel?

    

      B. True or False. Correct the false sentences and make it true

     1. A fundamental skill of professional seamanship is being able to maneuver a vessel.

     2.  Ship-handling is about staying and jumping a berth

     3. Understanding of how the wind, tide and swell is not a priority

SHIP BREAKING

A.    Read the text below Carefully

Ship breaking or ship demolition is a type of ship disposal involving the breaking up of ships for scrap recycling, with the hulls being discarded in ship graveyards. Most ships have a lifespan of a few decades before there is so much wear that refitting and repair becomes uneconomical. Ship breaking allows materials from the ship, especially steel, to be reused.

Ship breaking near Chittagong, Bangladesh

In addition to steel and other useful materials, however, ships (particularly older vessels) can contain many substances that are banned or considered dangerous in developed countries. Asbestos and polychlorinated biphenyls (PCBs) are typical examples. Asbestos was used heavily in ship construction until it was finally banned in most of the developed world in the mid 1980s. Currently, the costs associated with removing asbestos, along with the potentially expensive insurance and health risks, have meant that ship-breaking in most developed countries is no longer economically viable. Removing the metal for scrap can potentially cost more than the scrap value of the metal itself. In the developing world, however, shipyards can operate without the risk of personal injury lawsuits or workers' health claims, meaning many of these shipyards may operate with high health risks. Protective equipment is sometimes absent or inadequate. Dangerous vapors and fumes from burning materials can be inhaled, and dusty asbestos-laden areas around such breakdown locations are commonplace.

Aside from the health of the yard workers, in recent years, ship breaking has also become an issue of major environmental concern. Many developing nations, in which ship breaking yards are located, have lax or no environmental law, enabling large quantities of highly toxic materials to escape into the environment and causing serious health problems among ship breakers, the local population and wildlife. Environmental campaign groups such as Greenpeace have made the issue a high priority for their campaigns.

Source : Cutler, Thomas J. (1999). The Bluejacket's Manual (Bluejacket's Manual, 22nd ed). Annapolis, Md: Naval Institute Press. ISBN 1-55750-065-7.

B.     List Of Vocabularies

1.      disposal            : Pembuangan

2.      lifespan            : Jangka pajang

4.      polychlorinated :poliklorinasi

5.      scrap                 :Membatalkan

6.      viable                : Giat

7.      fumes                : Uap

8.      inhaled              : dihirup

9.      priority             : Utama

10.  breakers          : Pemutus

C.    Question

a)      Answer the question below based on the text.

1.      What is “ship breaking”?

2.      Explain the function of ship breaking.

3.      Why was Asbestos and polychlorinated biphenyls (PCBs) banned in a ship?

4.      “in ship construction until it was finally banned”. The word “it” in the sentence refer to?

5.      What is the main idea of the last paragraph?

b)     True or false

1.      Most ships have a lifespan of a few decades before there is so much wear that refitting and repair becomes economical. (T/F)

2.      Asbestos was used heavily in ship construction until it was finally banned in most of the developed world in the end 1980s. (T/F)

3.      Removing the metal for scrap can potentially cost less than the scrap value of the metal itself.(T/F)

4.      Dangerous vapors and fumes from burning materials can be inhaled, and dusty asbestos-laden areas around such breakdown locations are commonplace.

5.      Environmental campaign groups such as Greenpeace have made the issue a high priority for their campaigns.