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Propeller Propeller and the stern tube is an independent survey items from the docking surve y.  But the classification rules in docking survey say as follows: " The propeller and the after end of the stern bush are to be examined. The clearance in the stern  bush and the efficiency of the oil gland should be ascertained. In the case where a controllable  pitch propeller is fitted, it is to be ascer tained that the pitch control device is in good working order, and, if considered necessary, the device is to be opened up for further examination." These survey are responsible on the Machinery surveyor . But hull surveyor also  have some elementary knowledge  on propeller and stern tube. The followings are only guidance concerning to these items. 11-1 Propeller Damage  The biggest damage of propelle is the broken blades; while sailin , when abnormal vibration suddenly happens in the stern and continues, it may be caused because of the broken propeller  blade . In this case, the engine should be stopped, then the extent of damage to be checked and depending on the dama ge, the ship should visit to the nearest port for an Occasional Survey. If more than one-third of the blade is b roken, there is a possibility that the damage also occurred to the stern tube. In the dry dockd not only propeller but stern tube should be carafully examined. Sometimes propeller shaft should be withdrawn. The causes of this damage are contacting with a submerged or floating obje ct or small material defect during manufacturing which developt to hair cracks, and or metal fatigue. 11.1.2 Bend of blade Bend occurs because of impact of the propeller with other objects; they can be detected easily even before the propeller is cleaned. 11.1.3 Cracks Small cracks are overlooked in many cases. They cannot be detected unless stagings are erected and after cleaning of each blade. Even the hair cracks they have a possibility of expanding and  breaking the propeller blade. Thse hair cracks are discovered by dye penetration test. Generally this test need not be carried out for the entire surface of the blade; it is customary to check only the area from the root to 0.4R of the blade. In the previous dock if a stop-hole has been drilled at the crack end and the hole has been filled with a wooden plug, pa y attention whether crack ia extended o r not. In this case refer to previous Survey Record on this matter.

Propeller crack

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Propeller

Propeller and the stern tube is an independent survey items from the docking survey.  But the

classification rules in docking survey say as follows:" The propeller and the after end of the stern bush are to be examined. The clearance in the stern

 bush and the efficiency of the oil gland should be ascertained. In the case where a controllable pitch propeller is fitted, it is to be ascertained that the pitch control device is in good workingorder, and, if considered necessary, the device is to be opened up for further examination." These

survey  are responsible on the Machinery surveyor . But hull surveyor also  have some 

elementary knowledge  on propeller and stern tube. The followings are only guidance

concerning to these items.

11-1 Propeller Damage 

The biggest damage of propelle is the broken blades; while sailing, when abnormal vibration

suddenly happens in the stern and continues, it may be caused because of the broken propeller  blade . In this case, the engine should be stopped, then the extent of damage to be checked and

depending on the damage, the ship should visit to the nearest port for an Occasional Survey.If more than one-third of the blade is broken, there is a possibility that the damage also occurred

to the stern tube. In the dry dockd not only propeller but stern tube should be carafully examined.Sometimes propeller shaft should be

withdrawn.

The causes of this damage are contacting with a submerged or floating object or small materialdefect during manufacturing which developt to hair cracks, and or metal fatigue.

11.1.2 Bend of blade Bend occurs because of impact of the propeller with other objects; they can be detected easilyeven before the propeller is cleaned.

11.1.3 CracksSmall cracks are overlooked in many cases. They cannot be detected unless stagings are erectedand after cleaning of each blade. Even the hair cracks they have a possibility of expanding and

 breaking the propeller blade. Thse hair cracks are discovered by dye penetration test.

Generally this test need not be carried out for the entire surface of the blade; it is customary tocheck only the area from the root to 0.4R of the blade.

In the previous dock if a stop-hole has been drilled at the crack end and the hole has been filled

with a wooden plug, pay attention whether crack ia extended or not. In this case refer to previous

Survey Record on this matter.

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 Photo.11-1 Blade broken (1)

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 Photo.11-2 Blade broken (2)

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 Photo.11-3 Blade bent

11.1.4 Corrosion Similar to the rudder, the propeller blade may be subjected to spongiform corrosion (erosion) dueto cavitation. There is no good repair method; the surface can be smoothed using a grinder, or 

depending on the position, the blade can be built up by welding, If the corrosion is severe, the

corroded part may be cut out and using the approved material and repaired   by welding. These

welding repairs should be entrusted to the propeller manufacturers because welding  of copper alloys is very difficult.

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 Photo.11-4 Hair crack on the blade

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 Photo.11-5 Blade errosion

11-2 Inspection of Blades According to data on cracks and broken blades, the blade is frequently cut at the location called

the P point; therefore, this part should be inspected with particular care. The P point lies on the

 pressure side of the blade, and it is the point where the thickness of the blade is maximum andwhere the rounded radius of the boss terminates. The indication of the position on the propeller is

similar to the concept of the frame space indicating the position of the frame and beam shown in

the figure 11-1 below.

The blade is divided into parts formed by measuring arcs from the centre

of the propeller at every 10% of the radius of the propeller, such as 0.4R, 0.7R. The names of the blades are generally assigned as A, B, C, D and

E or (1), (2), (3), (4), and (5) in case of five-bladed propeller.

The name of each blade is engraved at the root of the blade. It can be find easily after green algae

or dirt on the propeller blade has been removed.The area shown in the figure should be inspected with special care. After polishing the surface

using a disk sander along the length of the blade, the surface should be examined using a hand

magnifying glass or by performing the dye penetrant test. For details of the dye penetrant test,

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 以下未校正 

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 Fig.11-1 Propeller Nomenclature (1)

Fig.11-2 Propeller Nomenclature (2)

11.3 Propeller Repair The surface of the propeller blade is divided into three regions: A, B and C. The table belowshows the kinds of repairs that can or cannot be carried out in each region.

However, only typical damage and inspection procedures are covered here.

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 Fig.11-3 The area for dye penetration test

Fig.11-4 Propeller blade

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R = Radius, Ct = Chode lenght in rudius r 

Table 11-2-2 Kind of repair 

11.4 Fall of Guard Ring A guard ring (also called a rope guard) is fitted between the propeller front face and the sternframe to prevent floating objects such as fishing nets from being fouled with the propeller shaft.

The guard ring is a split ring welded to the boss of the stern frame. It can come off easily if an

object hits it. A guard ring is not prescribed by the Rules, but if it has fallen off,it must be replaced by manufacturing a new ring and fitting it in place.

Fig.11-4 Gurd ring

12.5 Clearance Measurement

The clearance between the propeller shaft and the bearing should be measured during the bottom

inspection. There are two methods of 

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measuring clearance, depending on the water  — sealing method for the shaft. For the rudder, the

clearances in the longitudinal (fore-aft) and

transverse (p-s) directions of the rudder shaft are measured, but for the propeller shaft, becausethe lower surface of the shaft is in contact with the bearing, only the clearance of the upper 

surface of the shaft has to be measured in case of a water--lubricated system.

Fig.11-5 Clearance  of stern tube bearingFor an oil lubrication  system, also measure the clearance at the lower surface.

However, for an oil — lubricated system, clearances of the upper and lower surfaces have to be

measured, because the shaft sinkage is small. Clearances in the transverse direction need not be

measured because the shaft is rotating all the time.

11.5.1 Clearances of sea water — lubricated bearingsSimilar to measuring the clearance of the rudder pintle, remove the guard ring, insert the feeler 

gauge or the measuring wedge from the stern tube side and measure the clearance. Before the

lignumvitae dries out after the ship is drydocked, measure the clearance of the upper surface andrecord the results of the measure-ments in the Inspection Record Form M-1. For 

a ship with twin shafts, item 1. in the form is for the propeller on starboard side, and item 2. isfor the port side. If a twin — shaft ship has shaft

 brackets, enter the measurements in the lower Dart of the form

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Fig.11-6 Measurement of Clrarance

Table 11-2 Results of mesurement (1)

The allowable maximum clearances according to shaft diameter are given below. If the values below are exceeded, the stern tube bearing material should be replaced or repaired.

Table 11-3 Allowable max. clarance

12.5.2 Weardown of oil — lubricated bearings Unlike lignumvitae used in water 

 — lubricated bearings, metal can be used in oil

 — lubricated

 bearings, and the clearance between shaft and bearing can be reduced. Wear is also small, and

most modern ships use oil — lubricated bearings.Clearances should be measured at the same shaft positions as the previous measurement. To

specify the shaft position, use the position of 

the propeller blade or the position of the main engine piston. Generally, this position is specifiedaccording to the position of the propeller blade; for example, measure clearance with blade A at

the top. If no hole for measuring sinkage is provided in the guard ring, the guard ring should be

removed, the screwed cap of the measuring hole removed, and a measuring instrument such as

Vernier calipers, so — called wear down gauge, inserted and distances from the bearing to the

upper and lower surface of the shaft measured. The measued records is to be entered in the

survey report showing the position of measured point sucha sa the Key Top or No. 6 Crank Top.;however, unless the bonnet is removed, the key position cannot be judged; therefore, it is

convenient to take a specific blade (cylinder) as the reference for sinkage measurement. In largeships today, propellers are generally keyless. Sinkage is the difference in measurement at the

time of inspection and measurement when the ship was built. The standard limit for sinkage is

0.3 mm irrespective of the shaftdiameter. Sinkage should be determined by studying the properties of lubricating oil, and the

history of temperatures of the lubricating oil and bearing material. An example of the Inspection

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Record is shown below.

Photo.11-6 Measuring  clearnce

Example of position propeller shaft

Fig.11-7 Position of propeller blade

Table  11-4 Results of measurement (2)

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(1) Example of measuring clearance in a oil-lubricated bearing

(1) Original

(2) Overhaul of guard ring and cap bolt

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(3) Inserting the gauge

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 (4) Measurenent

Fig. 11-5 Measuring of propeller shaft clearance

(2) Example of measurement results for sinkage 

Measurement results for two ships and their graphs are provided below for reference.The part above the kinked line shows the top, and the part below the kinked line shows the

 bottom measurement values. The position of the blade does not conform to the key top position

 but the No. 8 piston top position.

Ship (1) : Tanker, 72,368G/T,built in 1975

Month Measurement Month Measurement

4/1977 114.30114.85 6/1978 115.40/114.75

9/1979 115.50/114.80 11/1980 115.50/114.80

5/1982 115.60/114.80 9/1983 115.30/114.70

5/1985 114.90/114.70 11/1986 114.90/114.60

10/1988 114.90/114.60 10/1990 115.10/114.90

9/1992 115.40/115.00

Ship (2) : Tanker, 43,444G/T, built in 1975

Month Measurement Month Measurement

12/1981 72.7/73.1 4/1984 72.6/73.2

5/1986 72.9/73.1 6/1988 73.3/73.3

4/1990 73.4/73.3 5/1992 73.3/73.4

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Fig.11-6 Results of measurement (3)

11.6 Inspection of Stern Tube Seal Oil leaks from the propeller boss in the stern frame of an oil — lubricated system can sometimes

 be detected during a bottom inspection. This is probably due to a defective seal, therefore, adetailed examination of the

seal is necessary.

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 Fig.11-7 Oil leakage from propeller boss

11.7 Bow Thruster and Side Thruster

These items are shipowner's options, therefore, they need not be inspected under class

requirements. However, if these items areinstalled on the ship, they should be inspected at the docking survey. Frequently observed

damage includes damage to guards at sea water ports due to impact with submerged or floatingobjects, and bent propeller blades. If the shaft seal is defective, water entersin to the ship;however, such incidents are not reported. Inspection results should be entered in the Survey

Report.

When the stainless plate is used in the surface of the nozzle, the corrosion of adjusent steel plate  suould be carafully inspected.

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 Fig.11-8 Damage of side thruster guard

Fig.11-9 Damage to side thruster 

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Terjemahan

Baling-baling 

Propeller dan tabung buritan merupakan item survei independen dari survei docking. Tapiaturan klasifikasi dalam survei docking mengatakan sebagai berikut:

"Baling-baling dan setelah akhir buritan semak harus diperiksa. Clearance di buritan semak dan

efisiensi kelenjar minyak harus dipastikan. Dalam kasus di mana baling-baling lapangan

dikontrol dipasang, itu adalah untuk dipastikan bahwa perangkat kontrol pitch adalah dalamrangka kerja yang baik, dan, jika dianggap perlu, perangkat ini harus dibuka untuk pemeriksaan

lebih lanjut. " Survei ini bertanggung jawab pada surveyor Mesin. Tapi lambung surveyor 

 juga memiliki beberapa pengetahuan dasar pada baling-baling dan tabung buritan.Berikut ini adalah hanya pedoman mengenai item ini.

11-1 Kerusakan Propeller 

Kerusakan terbesar propelle adalah pisau patah, sedangkan sailin g, ketika tiba-tiba terjadi

getaran yang abnormal di buritan dan terus, mungkin disebabkan karena pisau baling-balingrusak. Dalam hal ini, mesin harus dihentikan, maka tingkat kerusakan yang akan diperiksa dan

tergantung kerusakan, kapal harus mengunjungi ke pelabuhan terdekat untuk Survey Sesekali.

Jika lebih dari sepertiga dari pisau rusak, ada kemungkinan bahwa kerusakan juga terjadi padatabung buritan. Dalam dockd kering tidak hanya baling-baling tapi tegas tabung harus carafully

diperiksa. Terkadang poros baling-baling harus

ditarik.Penyebab kerusakan ini dengan menghubungi terendam atau mengambang objek atau cacat

 bahan kecil selama manufaktur yang developt untuk retak rambut, dan atau kelelahan logam.

11.1.2 Bend pisau Bend terjadi karena dampak dari baling-baling dengan benda lain, mereka dapat dideteksi

dengan mudah bahkan sebelum baling-baling dibersihkan.

11.1.3 Retak  Retakan kecil diabaikan dalam banyak kasus. Mereka tidak dapat dideteksi kecuali stagings yang

didirikan dan setelah membersihkan pisau masing-masing. Bahkan rambut retak mereka

memiliki kemungkinan untuk memperluas dan melanggar pisau baling-baling. Thse retak rambut

yang ditemukan oleh uji penetrasi pewarna.Umumnya tes ini tidak perlu dilakukan untuk seluruh permukaan pisau, adalah kebiasaan untuk 

memeriksa hanya daerah dari akar ke 0.4R pisau.

Di dermaga sebelumnya jika stop-lubang telah dibor pada akhir retak dan lubang telah diisi

dengan plug kayu, perhatikan apakah retak besarbesaran diperpanjang atau tidak. Dalam hal inimengacu pada sebelumnya Survei Record pada hal ini.

Photo.11-1 pisau rusak (1)

Photo.11-2 pisau patah (2)

Membungkuk Photo.11-3 pisau

11.1.4 Korosi 

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Mirip dengan kemudi, pisau baling-baling dapat dikenakan spongiform korosi (erosi) akibat

kavitasi. Tidak ada metode perbaikan yang baik, permukaan dapat merapikan menggunakan

 penggiling, atau tergantung pada posisi, pisau dapat dibangun dengan pengelasan, Jika korosi parah, bagian yang berkarat dapat dipotong dan menggunakan bahan dan disetujui diperbaiki

dengan pengelasan. Ini perbaikan pengelasan harus dipercayakan kepada produsen baling-baling

karena pengelasan paduan tembaga sangat sulit.

Photo.11-4 retak rambut pada pisau

Photo.11-5 pisau errosion

11-2 Pemeriksaan Blades Menurut data retak dan pisau patah, pisau sering dipotong di lokasi disebut titik P, karena itu,

 bagian ini harus diperiksa dengan penanganan khusus. P Titik terletak pada sisi tekanan pisau,

dan itu adalah titik di mana ketebalan pisau maksimum dan di mana jari-jari bulat bos berakhir.Indikasi posisi pada baling-baling ini mirip dengan konsep ruang bingkai menunjukkan posisi

dari frame dan balok yang ditunjukkan pada gambar 11-1 di bawah ini.

Pisau ini dibagi menjadi bagian-bagian yang dibentuk dengan mengukur busur dari pusat

 baling-baling pada setiap 10% dari radius baling-baling, seperti 0.4R, 0.7R. Nama-nama pisauumumnya ditugaskan sebagai A, B, C, D dan

E atau (1), (2), (3), (4), dan (5) dalam kasus propeller lima berbilah.

 Nama masing-masing pisau yang terukir pada akar pisau. Hal ini dapat menemukan dengan

mudah setelah ganggang hijau atau kotoran pada pisau baling-baling telah dihapus.Area yang ditunjukkan pada gambar harus diperiksa dengan perawatan khusus. Setelah polishing

 permukaan menggunakan sander disk yang sepanjang pisau, permukaan harus diperiksa dengan

menggunakan kaca pembesar tangan atau dengan melakukan uji dye penetrant. Untuk rinciandari uji dye penetrant,

以下未校正 

Gbr.11-1 Propeller Nomenklatur (1)

Gbr.11-2 Propeller Nomenklatur (2)

11.3 Propeller Perbaikan Permukaan pisau baling-baling dibagi menjadi tiga wilayah: A, B dan C. Tabel di bawah inimenunjukkan jenis perbaikan yang dapat atau tidak dapat dilaksanakan di setiap daerah.

 Namun, kerusakan dan prosedur inspeksi hanya khas yang dibahas di sini.

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 Gbr.11-3 Daerah untuk uji penetrasi pewarna

Pisau Gbr.11-4 Propeller 

R = Radius, Ct = Chode panjang di rudius r 

Tabel 11-2-2 Jenis perbaikan

11.4 Kejatuhan Penjaga Cincin Sebuah cincin penjaga (juga disebut penjaga tali) dipasang antara wajah depan baling-baling dan

frame tegas untuk mencegah benda mengambang seperti jaring ikan dari diganjal dengan poros baling-baling. Cincin penjaga adalah split ring dilas ke bos dari frame buritan. Hal ini dapat

datang dengan mudah jika sebuah objek hits itu. Sebuah cincin penjaga tidak diresepkan oleh

Aturan, tetapi jika itu telah jatuh,

harus diganti oleh manufaktur cincin baru dan pas pada tempatnya.

Gbr.11-4 Gurd cincin

12.5 Pengukuran Izin Clearance antara poros baling-baling dan bantalan harus diukur selama pemeriksaan bawah. Adadua metode

mengukur clearance, tergantung pada metode air penyegelan untuk poros. Untuk kemudi, jarak 

 bagian memanjang (depan-belakang) dan

melintang (ps) arah dari poros kemudi diukur, tapi untuk poros baling-baling, karena permukaan bawah poros dalam kontak dengan bantalan, hanya pembersihan permukaan atas poros harus

diukur dalam kasus air - sistem dilumasi.

Gbr.11-5 Izin tabung bantalan tegasUntuk minyak pelumas sistem, juga mengukur clearance di permukaan bawah.

 Namun, untuk sistem minyak pelumas, jarak dari permukaan atas dan bawah harus diukur,

karena sinkage poros kecil. Kelonggaran dalam arah melintang tidak perlu diukur karena poros berputar sepanjang waktu.

11.5.1 Jarak bebas laut bantalan air dilumasi Mirip dengan mengukur clearance