Traffic Systems of the Kii§3
Suido (Strait) and Tokyo Bay
We referred to the traffic system in §2-3-3, and the author conducted BTM briefings for navigation officers when they
are operating in the sea area. We are pleased to introduce these to you for your reference.

§3-1 The Kii Suido (Strait)(See Fig. 30: Attachment ①

The Kii Suido (Strait)Traﬃc System Chart Enlargement)This sea area can be roughly divided into the following two sea routes:① The route that goes to and from Osaka Bay via the Tomogashima Strait (indicated by the red
green

and

lines on the map).

② The area off the Kii Peninsula ‒ Naruto Strait route (only suitable for small vessels under 5,000 GT)

When going to and from the Seto Inland Sea, these voyage routes are measurably shorter than going through the
Akashi Strait (which takes an indirect route around Awaji Island).

17 to 19
nautical miles

I ShimaHino-Misaki

Fig. 30

The Kii Suido (Strait)− 36 −

Traﬃc System ChartBecause these two traffic systems are crossing in the Kii Suido (Strait), this means that this is an area in which it is necessary to be on the alert at all times. Article 15 of COLREGs (Crossing Situation) was most generally applied in this area.
However, as can be seen on the map, the crossing of vessels in this area takes place at an angle close to overtaking, and if thegive-way vessel uses a change of course in order to avoid collision, she is forced to use a large angle to change course.
In the case explained in this report, if Vessel A used a momentary heading manoeuvre in the direction of the astern ofVessel B in order to avoid collision, she would have to change course from 190 to 248 degrees.
When a large angle to change course of this type is performed in these waters, as in the case of Vessel A, the bow of
the give-away vessel ended up pointing in the direction of Tokushima. Naturally, even if she turns towards the asternof the other vessel, the give-way vessel can be manoeuvred in such a way as to follow the astern, making it possible
to return reasonably quickly to her original course. Therefore, the deviation of the give-way vessel from the originalcourse is not that great. However, psychologically, this means heading the vessel straight towards the coast, navigation
officers without much experience and whose technical skills are not sufficient can hesitate to carry out such an avoidance action. In view of this, and as seen in the accident presented in this report, this allows some understanding of thefact that the third officer of Vessel A in question only changed heading course by 6 degrees.
If the vessel in question is heading towards Osaka Bay, she can navigate following the traffic system leading towards
the Naruto Strait. The vessel can successfully fade out from the sea off Hinomisaki and head towards TomogashimaIsland. This is not a particularly difficult manoeuvre.
A vessel heading towards Osaka Bay from the sea off Muroto and navigating along the coast of the Kii Peninsula
in a north-easterly direction can see another vessel heading towards the Naruto Strait (north-west operation vessel
indicated by the blue line on the map) on her starboard side. This makes the vessel heading towards Osaka the giveway vessel.
Especially in the area between Shionomi and the Naruto Strait, the many coaster vessels navigate in a line, so thecrews of these vessels must experience difficulties in trying to avoid collisions with other vessels.
If a vessel trying to push across from I-shima Island to Hinomisaki is in danger of being hit in the sea off Hinomisaki
by a crossing vessel heading towards the Naruto Strait, the said vessel will have to make a wide turn to starboard at
the mouth of the Kii Suido (Strait). However, as the coast is visibly very close, it is difficult to find a stretch of waterthat will allow her to alter her course to starboard side in order take avoidance action.
Therefore, one suggestion when navigating in the wide sea area heading from the sea off Cape Muroto to Osaka Bay,
would be to follow the traffic system from Shionomi to the Naruto Strait, and to position the vessel in the wide waters
to the south of Hinomisaki, and to then take a course allowing a successful fade out in the sea area off Hinomisaki.
It is true that the vessels heading towards the Naruto Strait navigate in a line, but as in the same way as a car trying to
get on to an express way, it is possible to find gaps in the traffic.
An additional fact is that there are many fishing vessels in the waters in this sea area. Vessels also come and go fromthe ports of Wakayama and Komatsushima, meaning that this sea area can be described as being congested. The point
where pilots who navigate Osaka Bay are taken on board is about 1.5 nautical miles from the Tomogashima Strait. In
order to board the pilots who will navigate the Osaka Bay, many vessels have to slow down and prepare the engines(S/B Eng.). It may be because of this that, vessels in the area have to change heading course broadly in order to avoid
collision in these, as mentioned above, congested sea areas. This causes a disruption to the whole sea traffic system (asthe same would happen in the case of a motor vehicle changing lanes suddenly).

− 37 −

Therefore, when preparing to enter the Osaka Bay, at a point of 5 nautical miles from Hinomisaki, it is important tohave the engines on standby ready to use at any time and to reduce speed in order to be able to carry out avoidance
action at any time.
Moreover, when leaving Osaka Bay and heading southbound, until the vessel is clear of the traffic system between the
Naruto Strait and Shionomisaki, the engines should be in S/B mode. It goes without saying that the Master should be incommand of operations, and depending on the circumstances, it will be necessary to utilise sub-officer of the watch andadditional lookouts as reinforcements.

§3-2(See Fig. 31: Attachment ②

Tokyo Bay

Tokyo BayTraﬃc System Chart Enlargement)This sea area has a higher volume of marine traffic than Osaka Bay. Also, there are several complicated traffic routes
such as a vessel heading towards Tohoku along Chiba Prefecture at the entrance of Tokyo Bay, a vessel crossing the
Pacific Ocean from the sea off Nojima-Saki, and a ship navigating the O-Shima northern route and another ship sailing the O-Shima southern route. And these vessels concentrate in the sea off the coast of Tsurugi-Saki in the southeastof the Miura Peninsula.
There is more complicated movement of vessels found at the point of embarkation or disembarkation for pilots inTokyo Bay: because this point is approximately 1.0 to 1.5 nautical miles south of the Uraga Suido Traffic RouteNo.1 buoy. Oceangoing vessels have no choice but to decrease speed drastically in order to let the pilot embarkation
or disembarkation in such a congested traffic system. Furthermore, in this sea area where vessels concentrate, an
unavoidable more complicated give-way takes place, as vessels are crossing and overtaking other vessels.
Generally, there are many coaster vessels that operate the O-Shima northern route. Vessels from Tohoku to Ise Bay,Kansai are (or vice versa) are crossing over the exit of Tokyo Bay off the coasts of Nojima-Saki and O-Shima in thesea area. (course shown in blue line on the chart)
Safe navigation in this sea area is to operate at S/B speed, while keeping the engine on standby all of the time because
the traffic in the sea area is congested. Many large ocean-going vessels have no choice but to make plans to slow
down towards the pilot’s embarkation point, or to start accelerating (R/Up Eng.) immediately after having let the pilot
disembark. However, in congested sea areas like these, avoidance action should be taken by reducing speed without
hesitation, just the same as with cars, and not only through taking avoidance action by changing to a wide heading
course by force. When the Author was a new Master himself, such unreasonable operations to attempt (S/B Eng.) (enter the bay) around the point of embarkation or disembarkation for pilots and to accelerate (R/UP Eng.,) immediately
after the pilot disembarked were enforced. However, as a Master and having gained experience of such an operation,
the author became more cautious and exercised safe navigation (S/B or R/UP Eng.) off Su-no-Saki.
It is necessary to fully understand these traffic systems in the Kii Suido (Strait) and Tokyo Bay, which were discussed
above. It is also necessary for managers on shore to explain sufficiently to the Masters of ocean-going vessels, who do
not have enough navigation experience in these sea areas.

− 38 −

Hazard zone

Tsurugi SakiNorth of Izu O-shima Route(Mainly Coaster Vessels)

Coaster vessels

South of Izu O-shima Route(Mainly Ocean going Vessels)
East ⇔ West route which does notenter Tokyo Bay (coaster vessels)

Fig. 31

Tokyo BayTraﬃc System Chart− 39 −

Ocean going vessels

§4Engine Trouble and
Oil Spill Accidents§4-1 Feature of Trouble and Damages(Attachment ③ See 4 Cycle Diesel Engine of vessel )Firstly, an explanation about engine trouble in general. Please also refer to the P&I Loss Prevention Bulletin ‘Thinking
Prevention of Engine Trouble’ (Vol.38).

§4-1-1

Damage that Affects Ship Operation

The following main parts among the components of a main engine are large, both in size and weight.
（1） Power output section: Piston/Cylinder liner（2） Driving mechanism: Connecting rod/Crankshaft

In the event that these parts are damaged, the repair is generally large-scale. At the same time, damage to such parts
will also affect ship operation. In addition, because the repair itself is difficult, it requires experience and a high levelof skill. As a result, owing to either of the following reasons, it takes time for the vessel to be made serviceable again.
Therefore, it is necessary to lay out a framework in order to prevent accidents.
(1) If it is beyond the capacity of the crew, it will be necessary to arrange for the manufacturer
or a repair worker to intervene.
(2) Even if the crew were to attempt a repair, they would not be so accustomed to it.

On this occasion, in order to study the accident cases, we referred to the Marine Accident and Incident Reports
regarding engine trouble and vessel damage available from Japan Transport Safety Board of Ministry of Land, Infrastructure, Transport and Tourism homepage. According to the Reports, there were 138 accounts of engine trouble anddamage over a period of eight years from January 2008 through to June 2016; these breakdowns and damage accounts
occur mainly in the following part of the main engine (except for pleasure craft and fishing boats).
Piston/Cylinder liner/Cylinder head
Turbo charger

Crankshaft bearing/Crank pin bearing

Reverse and reduction gear

Air intake & exhaust valve

Coastal vessels were mainly referred to in this report. Coastal vessels have smaller engine rooms and operate at a
− 40 −

lower output, compared with ocean going vessels. Also, most of them have 4 cycle diesel engines, not 2 cycle diesel
engines that are found on many ocean going vessels. However, the Report focuses on many themes regarding trouble
and damage to owners and ship managers of both coastal vessels and ocean going vessels.

§4-1-2

Damage Characteristics - by Equipment

Each characteristic will be described below, according to the frequency of the equipment that tends to be damaged.
（1）

Piston, Cylinder Liner and Cylinder Head(except for chain accident related with Air Intake & Exhaust Valve)

Approximately half of the damage to pistons, cylinder liners and cylinder heads were due to burnout. Most piston
structures comprise of a cooling system using lubricating oil (hereinafter LO), but burnout is caused by a short supply
of cooling oil. This shortage is also caused by a shortage of LO pressure and a blockage in the cooling oil supply
route.
Moreover, there are cases of bending damage to the push-rods because of damage sustained to the exhaust valvecaused by a strike from the piston crown due to the looseness of the fixing bolt between the piston crown and thepiston skirt. The following measures are taken:●

Crew are to understand the risk of damage to an engine when disassembling and assembling it.

●

When disassembling and carrying out maintenance, crew should confirm and inspect theparts carefully again before assembling, in order to avoid assembly mistakes regarding important parts such as the LO channels and tightening of parts.

（2）

Crankshaft bearing/Crank pin bearing

Most damaged sustained by crankshaft bearings is due to a lack of LO.
This is because the sludge in the LO builds up in the strainer and filling pipe due to neglect of maintenance andinspection. In addition, most causes of damage to the crank pin bearing (large end of the connecting rod) come fromover-tightening, insufficient tightening or uneven tightening of the connecting rod bolt (hereinafter referred to as crank
pin bolt). The following measures are taken:●

To comply with and carry out the tightening method and force necessary based on the manufacturer's instruction manual.

●In every maintenance carried out, it is important to check for any cracks (dye penetration inspection), the bolt length (dimension measurement), length-of-use of components (comparedwith maximum hours of use) and to exchange the parts, if necessary.

（3） Turbo charger (except for air intake & exhaust valve chain accidents)

Damage to the turbo charger is related to damage sustained by the shaft (burnout of rotor shaft bearing, bending ofrotor shaft, breakage, etc.) and hole in the casing. The main cause of a hole appearing in the casing is due to thickness
depletion and corrosion sustained by long-term use. The following measures are taken:− 41 −

●

Measures taken against thickness depletion
To conduct a thickness measurement regularly and to exchange the casing based on the manufacturer's standard.

●

Prevention of corrosion
Carry out the quality check of cooling water (property analysis, chemical treatment, etc.) and appropriate temperature control.

（4）●Main Engine Reverse and Reduction Gear
There are many cases where damage to the main engine reverse and reduction gear iscaused by a problem concerning the hydraulic system. The preventive measures ensure thatthe maintenance and inspection of the hydraulic pump are carried out.

（5）

Air Intake & Exhaust Valve

The following are main damage accounts regarding air intake & exhaust valves:● Breakage of valve seat
● A valve detaches from its valve shaft and falls into the cylinder. As a result, the cylinder
head, piston and cylinder liner will be damaged.
● Furthermore, the fragments of damaged parts enter the turbo charger and cause damage to it.

Approximately half of the damage accounts of the air intake & exhaust valves cause damage to the turbo charger.
Even when maintenance is implemented regularly, damage can still occur. Preventive measures are to ensure thatthe crew confirms and inspects the following states described in the manufacturer’s instruction manual, when disassembling and maintaining.
●

To check and measure the cracks in the valve shaft and the valve seat (in order to verify
the wear and tear and deterioration state)●

To conﬁrm the length-of-use of component parts (compare with maximum hours of use)

（6） Summary

Summing up each aforementioned measure, it is important that confirmation with regards to the state of the engine
and inspection are thoroughly carried out, based on the manufacturer’s instruction manual during disassembly andmaintenance work. Namely, it is as follows:● Evaluate and replace the component parts based on the standard. (Deterioration, cracks,
dimension measurement, wear and tear, maximum hours of use, etc.)● During the assembly process, reconﬁrm and inspect repeatedly the same parts in order toprevent mistakes during the assembly of critical parts.

− 42 −

§4-2 Cases
The following cases will be introduced: ① a damaged piston and crank pin bolt, which may greatly affect navigation
when damaged, ② crank pin bearing damage, and ③ oil spill accidents that cause great harm to the environment.

§4-2-1Case ①

Piston Seizing and Piston Skirt Broken Damage Accidents（1）Outline of accident＜ Vessel’s particular ＞

Tanker Main engine output 2,942kw, built in 2001
＜ Summary of accident ＞

On March 2013, a broken hole appeared in the crankcase door of the main engine No.4 cylinder during operation,
which caused LO to gush out. Immediately, the watch engineer stopped the main engine. Then, as the result of inspection that both the chief engineer and the engine officer carried out, the following accounts of damage were detected.
①

Broken damage to piston skirt②

The broken damage part dropped down

Following consultation between the Master and the chief engineer, the Master deemed that the vessel was disabled fornavigation and the vessel was towed to the nearest port.
Before analysing the causes of the accident, piston structure and the flow of LO will be explained. (Please see Figs.
32, 33-1, 33-2 and end of booklet: Reference Attachment ③：‘4 Cycle Diesel Engine of vessel’)Snap Ring

Note: Parts information of Piston diagram

Piston Crown

Crank Pin Bearing

Piston Pin

Piston Skirt
Crankshaft

Connecting Rod

Oil Hole ofConnecting Rod

Main Bearing
Lubricationof each Piston
Pin Bearing
Passage to
Piston Pin
Filling Hole

Supply to Piston Cooling Space
Fig. 32

Piston diagram and Cooling oil supply route− 43 −

Piston Pin Metal

Snap Ring

Snap Ring
Piston Pin
Piston Pin
Piston Pin Metal
Snap Ring
Connecting Rod

Fig. 33-1

Fig. 33-2

Piston Pin Diagram

Piston Pin Diagram

The piston structure consists of two parts: an upper part and a lower part. The upper part has a special alloy pistoncrown and the lower has a cast iron piston skirt. The piston is of the assembly-type. The upper and lower parts areconnected by tightening bolts. The yellow line in Fig.32 shows the route of the cooling and lubricating oil that is
supplied from the main bearing.
The piston pin is a metallic hollow-shaped cylinder. The piston and connecting rod are connected via the boss
(borehole) in the piston skirt and a piston pin in the small end bearing of the connecting rod. Also, the piston pin (fullfloating type) has clearance between the small end bearing of the connecting rod and the piston pin boss. Both ends ofthe piston pin boss have a gutter.
As can be seen in Figs. 32, 33-1 and 33-2, the piston pin is prevented from coming adrift from the bearing by metal Cshaped retaining rings (hereinafter, snap rings) affixed in these gutter areas. In addition, there is a hole that allows for
LO (as cooling oil) to flow to the piston pin. This cooling oil is supplied from the oil hole in the connecting rod up to
the piston.
（2）The events that occurred

The sequence of the events that occurred is summarised as follows:①

Broken damage in the piston skirt of No.4 cylinder also occurred previously. Repair including the
replacement of new and remodeled parts carried out by an engine manufacturer was conducted in
October 2010.

②

Main engine LO consumption increased from around June, 2012. There is a possibility of abnormalities
at this point. Just before the accident, consumption increased by approximately three times to that ofnormal.

③This is why the chief engineer and engineer conducted the inspection of the crankcase, however, anabnormality was not detected.

④

Up until the trouble occurred, the chief engineer and engineer assumed that the cause of increased
LO consumption was down to abnormal wear of the piston rings. In fact, overhaul and maintenance
was reviewed during dock repair work that was scheduled on June 2013 (3 months later following theaccident).

− 44 −

When the accident occurred in March 2013, a description of the condition of No.4 cylinder is as below:（a）Piston skirt● The lower part of the oil ring of the port side piston skirt was severely
seized and sustain broken damaged● The broken damage part dropped down
● The bottom part of the piston pin boss was broken⑤（b）Piston pin boss（c）Snap ring（d）Cylinder liner⑥● There was a contact mark on the bow side of the piston pin boss on thefar outer side of the gutter, where the snap rings are inserted, that wascaused by surface contact from the piston pin.
● The snap ring of the bow side piston pin was broken in the centre andhad dropped down
● Had the snap ring been appropriately inserted into the snap ring gutter, acontact mark would naturally not have appeared.
● A vertical scratch approximately 5mm in depth sustained on the bow side
to cylinder liner

During navigation, a broken hole appeared in the crankcase door of No.4 cylinder, which caused LO
to gush out. The watch engineer stopped the main engine immediately.

（3）Analysis by Japan Transport Safety Board

Japan Transport Safety Board analysed the cause and recommended preventive measures as follows.
① Cause Analysis (Please see Figs. 32, 33-1, 33-2 and 43 on page 77 regarding diagrams)
Although the manufacturer carried out a repair in October 2010, the snap ring of the piston pin
boss was not fully inserted into the snap ring gutter during the assembly process. Due to this,the ring broke and dropped down during operation.
Thereby, the route for supplying LO was blocked because the piston pin moved to the axial
direction retarding the supply of LO. As a result, the piston was deprived of coolant, whichcaused it to seize and subsequently sustain broken damage to the piston skirt.
On the other hand, as for the time of the snap ring dropping down, it is pressumed to have occurred
around June 2012, when LO consumption had increased. Inferred grounds are as follows:●

Piston pin moved to the axial direction due to it dropping off the snap ring.

●Consequently, the following events occurred and LO consumption increased.

●

The piston pin made contact with the cylinder liner and vertical scratch damage was sustained.
Through the vertical scratch damage, cooling oil leaked into the combustion chamber and combusted.

●

Because the passage to the supply of LO became blocked and the piston was in need of coolant, theheated piston evaporated the LO nearby.

② Preventive measures by Japan Transport Safety Board

Based on the above analysis, the following are recommended as preventive measures that can be applied to similar
accidents in future.
The strengthening of supervision during assembly
While assembling the important parts of an engine, technicians are to carry out assembly correctly while under thesupervision of a supervisor who is familiar with the work.

− 45 −

To make inquiries to the manufacturer, when an abnormality has been discovered,and investigate its cause.
In the case of an extraordinary increase in LO consumption, the crew are firmly requested to make inquiries tothe manufacturer regarding the following:●

To check as to whether the increase of LO consumption is within the acceptable range.

●

If further necessary, investigate the cause at an early stage by disassembling each part.

Review of inspection methods by crew●

Crew should keep in mind the following, when inspecting the crankcase.
To observe carefully the state of the cylinder liner.
To try changing the piston position through turning for easier observation.

§4-2-2 Case ②

Crank Pin Bearing Damage Accident（1） Outline of Trouble＜ Vessel’s particulars ＞

Cargo ship Main engine output 1,080kW Built in 2004
＜ Summary of accident ＞

On October 2011, because the main engine automatically stopped with a loud sound during navigation, she dropped
anchor in an emergency at the end of the traffic lane nearby. On inspection during anchorage, the large end of theconnecting rod of No.7 cylinder passed through the crankcase door. After draw out of the No.7 piston, she shifted toanchorage by cutting operation of No. 7 cylinder. After that she was towed to port for repairing.
According to the investigation by Japan Transport Safety Board, the following accounts of damage were detected.

①

The state of the four crank pin bolts at the large end of the connecting rod of No.7 cylinder aredescribed as follows: (See Reference Picture 34)（a） Two bolts were cut at the stud bolt end（b） The other two bolts sustained bending damage in the middle section②

Broken damage of piston and cylinder liner (See Reference Pictures 35 and 36)③

Burnout of the crank pin bearing metal

Crank Pin Bolt

Reference Picture 34

Reference Picture 35

Reference Picture 36

Bending loss of connecting rod

Broken damaged cylinder liner

Broken damaged piston− 46 −

（2）The events that occurred

The sequence of the events that occurred is summarised as follows:①

On the 4th of October in 2010 (approximately one year before the accident occurred), the crew
carried out piston draw-out of the No.7 cylinder during regular inspection. During the assembling work,
they used a torque wrench to tightening in the crank pin bolts.

②

When the accident occurred, the cylinder was found to be in the following state:③（a）

Two of the bolts at the big end of the connecting rod had snapped and the other two bolts
sustained bending damage.

（b）

The connecting rod itself sustained bending damage

When the accident occurred, the main engine automatically stopped with a loud noise. Then, thefollowing parts had been damaged.
（a）Broken damage: piston and cylinder liner（b）Burnout: crank pin bearing metal（3）Analysis by Japan Transport Safety Board

Japan Transport Safety Board analysed the cause as follows and recommended preventive measures.
① Cause Analysis

The cause was that the crank pin bolt of main engine No.7 cylinder had snapped, which led to the freeing of the large
end and the consequent disconnection of the connecting rod from the crankshaft.
② Preventive measures

Based on the above mentioned analyses, the following was recommended as a preventive measure that can be applied
to a similar accident in the future.
● In the event of piston draw-out work, based on the guideline for maintenance work andstandard (instruction manual), maintenance of the crank pin bolt (replacement, dye penetration
inspection, cleaning, tightening force and so on) is to be carried out appropriately.

§4-2-3 Case ③

Oil Spill Accidents

On examination of oil spill accidents that our Club deals with, most accidents of this type which occur, excluding
collisions and those that run aground, are not cargo oil spill accident related but occur at the time of bunkering of fueloil (hereinafter FO).
（1）General Bunkering Procedure

First, an explanation of the general bunkering procedure. The vessel has FO bunkering work instructions from an environmental protection standpoint in accordance with the safety management system and manuals (hereinafter referred toas SMS). The work instructions generally consist of making a bunkering plan, a bunkering work plan, preparation forbunkering, work before oil receiving, receiving oil work, and work after bunkering. As can be seen in Table 37, the stepsof the procedure from the making of a bunkering plan to work before oil receiving are as follows.

− 47 −

①【Before bunkering】
Procedure
A. Previous port -During navigation -Entry into port

Operating situation

Making of bunkering planConﬁrmation of necessary bunkering amountⅠ

Ⅱa.

・Decided actual measurement of each tank, calculation of estimated consumption amount andprovisional amount for bunkeringConﬁrmation of receivable quantity
Make a plan that does not exceed 90% of the capacity of each tankⅢ

How much bunker oil is needed in each tank?

Ⅳ・Set in order of MDO (marine diesel oil) then HFO (heavy fuel oil) and plan the reﬁlling from a

Bunkering orderⅤⅥ

far-oﬀ tank procedure.
Valve operation order
・Carry out valve opening/closing test beforehand.

Bunkering work task assignment
・Task assignment and personnel arrangements

Bunkering work arrangement
Pre-meeting among all members of engine department regarding bunkering work arrangementⅠb.

・Role allotment (personnel arrangements): where, how much and into which tank the FO is tobe reﬁlled.
・Countermeasure in state of emergency

Ⅱ

All attendants sign their names after a meeting

Ⅲ

Keep all crew thoroughly informed regarding the importance of the bunkering work
arrangement.

Prepare for bunkering (the following work should be carried out, before and after port entry)
Final conﬁrmation of the actual level and remaining quantity of all FO tanks.
・The person responsible on scene must recalculate the plan, based on the actual fuel propertyⅠ

and actual remaining quantity in the tank・Transport necessary fuel to FO settling tank.
・Lock the FO transfer pump in order for it not to start automaticallyPrepare toolsc.

・ Sounding table, specific gravity & volume conversion table, calculator, watch, stationary,
Ⅱ transceiver, etc.
・Piping diagram, ﬁre extinguisher, oil removal material, sounding tape, thermometer, pressure
guage, tool, etc.
Ⅲ

Line-up・Entirely close unnecessary valvesⅣ

Set scupper plugs on deck

Ⅴ

Precision check of remote level gauge and operation check of each alarm on valve remotecontrol panel, indicating light, etc.

Ⅵ

Pressure test for bunker line during a dock or navigation before bunkering, if necessary

Ｂ Following port entrya.

Hoisting B ﬂag after entering port (Red light all-round at night)

C. Bunker barge alongside
Work before oil transfera.

Ⅰ
ⅡCheck the bunker oil volume on barge
・Conﬁrmation using sounding table of barge
Oil transfer volume
・Oil transfer capacity of barge and receivable quantity of vessel− 48 −

Remarks

a.

Ⅲ

Means of communication (transceiver etc.)

Ⅳ

Countermeasure in state of emergency

Ⅴ

After ﬁnal check, a signature is required from both the barge side and vessel sideⅥ

Hose connection

Ⅶ
Ⅷ

Contents conﬁrmation of Bunker Delivery Note(hereinafter, BDN)
・Oil type/oil quantity/oil property of fuel oil
Preparation for sample oil at collecting point

Table 37

Example of Bunkering Procedure① Making a bunkering plan

The bunkering plan is to be made by the filing in of the requirements in the list stipulated in the SMS, etc. At thisstage, in the same plan, the results of supposition calculation using figures based on previous bunkering oil temperatures, seawater temperatures, and fuel properties, etc., are filled in.
② A bunkering work plan

A person responsible on scene (generally a first engineer, described below as or hereinafter 1/E) makes a bunkering
work plan following the bunkering plan and explains it to each crew member following approval of the plan by thechief engineer. The 1/E explains the steps involved in bunkering work such as personnel arrangement, individuals
work responsibility, each work procedure, work method, countermeasure in state of emergency and so on.
③ Preparation for bunkering

In the preparation for bunkering stage, the person responsible on scene re-calculates the bunkering plan, based on theactual amount of fuel remaining in the tank and the actual fuel property just prior to bunkering. In other words, thepractice of PDCA concerning the bunkering work plan is essential④ Work prior to oil receiving

A third engineer (hereinafter 3/E) attends tank measurement on the bunker barge side or joins for reading aloud theinformation from the flow meter, and keeps a record to report to the person responsible on scene. The person responsible on scene re-calculates the requirement and completes the final bunkering plan. A point to confirm here is whether
the bunker barge retains the necessary amount and specification of fuel in accordance with the ordered amount or not.
Then, once the chief engineer approves the calculation result, the oil receiving begins.
⑤ Receiving oil work

During oil receiving acceptance, the crew of the engine department must pay attention to the following two duties.
1）To monitor oil leakage and tank liquid level

To verify any abnormality such as leakage
To carry out tank measurement regularly (Needless to say, but trim and heel correction is required when verifying the oil amount.)● A responsible person on scene is to calculate the rate of oil receiving flow. He also must know when it is time
to change tanks.
●●2）Appropriate action to be taken when there is an oil leakage●

When an oil leakage is found, the person responsible on scene should immediately announce the order to stop
pumping, and in the event of an overboard oil spill, the crew of the engine department must report it to the C/E
and duty officer immediately.

●

All crew onboard must handle this in accordance with the oil spill control station and shipboard oil pollution
emergency plan.

− 49 −

⑥ Work after bunkering

Having completed receiving work, the engine department not only submits the bunkering tank record to the deck
department, but also restores it to the normal fuel transfer line and fuel supply line promptly. Table 38 shows anexample of work instructions for both completed oil receiving work and post bunkering work.

②【During bunkering work】
Procedure
D. Commencement of bunkering

Operating situation

Oil receiving work
Ⅰ

After having started oil transfer and conﬁrmation of any leakages of oil, gradually increase the oiltransfer volume up to the planned quota.
Check the receiving tank liquid level at regular intervals (actual measurement by sounding scale).

Ⅱ

Ⅲ

Ⅳ

・Non-receivable tank: if ̀no inflow (no change of liquid level)ʼ after a certain interval since
starting, continuous monitoring is not necessary
Watch system, three persons at least
・One each for manifold and sounding, and a chief engineer (high command)
When receiving to more than two tanks, pay attention to manifold pressure at the time ofswitching tanks.
(Adjust the oil transfer volume, if needed)a.

ⅤCollecting sample oil

Ⅵ

After transferring oil, carry out air blowing.
Conﬁrmation of completion having received the arranged quantity (both for vessel and barge)
・Carry out tank measurement after bubbles have subsided.

Ⅶ・When there is no diﬀerence between receivable quantity and ordered quantity (OK), receivable
quantity will be written down on BDN and the chief engineer will sign the document.
・Issue Letter of Protest in case of shortage.
When something unusual happens, the person responsible on scene must stop the oil transfer
immediately.
・After conﬁrming the cause of the abnormality and measurement carried out, oil transfer can bere-started.

Ⅷ

Permission for restart of oil transfer by chief engineer is required.
・In the case of an oil spill into the sea, report it to both the chief engineer and to the duty
oﬃcer immediately.
Handle in accordance with oil spill control station and shipboard oil pollution emergency plan

E. Secure bunkering
Work following oil transfera.

I

Receiving oil sample for custodyII

Removal of hose

III

Secure each tool and B ﬂag (red light)IV

At appropriate time, restore the fuel line and bunkering line of vessel side to normal

V

Submit the record, i.e. ﬁnal bunkering quantity, tank condition, etc. to the deck department.

VI

Secure the sealed deck scupper

Table 38

Example of Bunkering Procedure− 50 −

Remarks

（2）Outline of accident

FO bunkering work was carried out on the vessel (approximately 8,000 GT) while it moored for cargo discharging work.
However, just at that time, the following accident occurred in the No.3 FO tank which was the last to top-up tank.

①

FO overﬂows from the air vent (See Reference picture 39)②

The crew could not contain the fuel on the deck and approximately 100 litters spilt into the sea(See Reference Pictures 40 and 41).

After the spill, the Japan Coast Guard and the vessel and shipowner arranged for seven work boats and cleaning
experts. The cleaning work was completed in one day. As a result, a sum total of approximately JPY 27,000,000 in
expenses was paid in insurance money for the investigation and cleaning up of the spilt FO.

Reference Picture 39

Reference Picture 40

No.3 Fuel oil tank air vent（after overﬂow）

Port side of upper deck

Reference Picture 41
State of oil spill overboarding− 51 −

（3）The events that occurred

According to the surveyor’s report, which was arranged after the accident, it was confirmed that the following events
led to the FO spill.

①

In the work carried out at a previous port, the second engineer, (hereinafter referred to as the2/E) was planning to carry out sounding of No.3 FO tank, which was set to ﬁnalize top-up tank.
However, he failed to carry this out.

②

Without conﬁrming the actual measurement in ① , the 1/E: the person responsible on scene, madethe bunkering plan, assuming that the tank had no remaining oil'. The plan for receiving oil wasscheduled to be carried out using four fuel tanks, in the following order: No.4 (port side andstarboard side), No.5 (central) and No.3 (central).

③

In addition, calculation details of the bunkering plan were not specified. The surveyor that
our Club arranged for accident investigation presumed that approximately 62KL, which isequivalent to 66% of the No.3 FO tank capacity on the bunkering plan (amount required fortank top-up), according to the investigation.

④

Although the 3/E and two oilers carried out tank measurement of the No.3 FO tank before
starting oil transfer, they did not realize how much remaining oil was left in the tank.

⑤

Also, even during receiving oil work, the 3/E and the oilers continued to measure the tankliquid level. In spite of the fact that receivable quantity was beyond the amount of the
bunkering plan, which was indicated above in ③ , they did not request that the oil transfer be
stopped. Consequently, because the receivable quantity was in excess of tank capacity, FO
overﬂowed from the air vent.

⑥

During tank overflow, the No.3 FO tank was filled with approximately 91KL of FO, which isequivalent to 96% of tank capacity. However, the oil transfer amount from the barge was as
instructed.

⑦

Therefore, though the stripping work was cancelled, the 1/E, who was the person responsible on
scene during bunkering work and in charge of maintaining contact between the barge and thevessel, was delayed in taking measures to initiate an emergency stop when it stated to overﬂow.

− 52 −

§4-3 Accident Analysis in Accordance with Error Chain
Not limited to marine accidents only, it is almost impossible for an accident to occur from a single error. A series oferrors cause an accident in the end. Regarding the three cases which were introduced in §4-2, we are going to analyseeach event from the perspective of error chains.

§4-3-1 Case ① Piston Seizing and Piston Skirt Broken Damage
The error chain of piston seizing and piston skirt broken damage accidents (Case ① ) was analysed according to timesequence.

Time-sequence ① Trusted entirely to the manufacturers
Time
In October 2010, main engine No.4 cylinder piston skirt sustained broken damage and-sequence
repair was carried out by the engine manufacturer.
①

Errors12

Related problems

The crew, ship owner and ship management company did not

Insuﬃcient ship

understand why it was replaced with remodeled parts.

management

Relied on the manufacturer because it was a replaced with aremodeled one (over-trusted)

Assumptions

Measures

Methods＜＜ Establish guidelines and ensure compliance with crew on ship ＞＞

Thorough instruction

In the case of discovering something unusual, make an inquiry to the manufacturer

Thorough ship manage-

for advice promptly and take emergency measures.

ment and supervision

Regarding repair by engine manufacturer, in spite of having exchanged the part with a remodelled one, crew, ownerand ship management company were not aware of the reason why.

Time-sequence ②
Investigation as to the cause was insufficient, despite the fact that LO consumption had increased
Increase of LO consumption as the sign of an accident cause was a phenomenal fact. Although the crew realized theabnormality, both the crew and the ship management company neglected to take the appropriate action.
Timesequence②

Trunk piston type lubricating oil is consumed mainly for lubrication between cylinder andbearing and cooling the piston. Since around June, 2012, the lubricating oil in the main
engine had been excessively consumed and - it increased to approximately three times thenormal amount just prior to the accident.

Errors12

Related problems

The Vessel noticed the unusual increase of consumption, however, it did not

Insuﬃcient daily duty

make inquiry to the manufacturer for further information.

management

There was no guideline for lubricating oil management.

− 53 −

Insuﬃcient ship
management

Measures

Methods＜＜ Establish guidelines and ensure compliance with crew on ship ＞＞

Thorough instruction

Prior to the manufacturer's repair, 'conﬁrmation and request for important
repair procedures, timing of watch on the ship's work site, the necessity of any
assistance, etc.' should be sought.

Time-sequence ③

Thorough ship
management andsupervision

Could not discover abnormal state when inspecting the crankcase

Time-sequence There was no abnormality discovered when inspecting inside the crankcase.

③
ErrorsRelated problems

At the time of inspecting inside the crankcase, why was 'the1

observance of the parts consisting of the piston, cylinder liner, etc.'
not carried out?

2
3

In the event of inspecting the cylinder liner, it is necessary 'to adjust
the piston location'.

Insuﬃcient daily duty
management
Crew's insuﬃciency ofworking skills
Insuﬃcient ship

There was no observation guidelinemanagement

Measures

Methods＜＜ Establish guidelines and ensure compliance with crew on ship ＞＞

Thorough instruction

In the event of inspecting the crankcase, it is also necessary 'to observe not only
for foreign substances (such as metalic pieces of bearings, combustion residue, etc.)
at the bottom of crankcase, but also inside of the piston skirt, the appearance ofthe connecting rod, the state of the cylinder liner and so on'. When inspecting thecylinder liner, it is necessary 'to adjust the piston location'.

A crankcase is, as shown in Fig. 42, a box shape room
which houses the crankshaft. As there is a door attached, it
is possible to inspect the inside. However, this door is too
small and it is not possible to observe the internal structure
without using a hand mirror or adjusting the positionof the crankshaft (See Fig. 42). There are three errorsthat occurred in the chain, when analysing as to why theabnormality was not detected at the time of inspecting the
crankcase.

Thorough ship
management andsupervision

CHECK!

Fig. 42 Appearance of Crankcase− 54 −

Time-sequence ④

Insufficient response to abnormal wear of piston rings

The crew presumed that the cause of unusual LO consumption (Time-sequence ② ) was a result of abnormal wear of
the piston rings, however, they did not report or making an inquiry to the ship manager or manufacturer.
Until the accident occurred, abnormal wear of the piston rings was assumed to be theTime-sequence cause (all of the cylinders were planned to be opened up and examined during the next④
dock repair work scheduled in June 2013).

Errors12

Related problems

Despite the fact that abnormal wear of the piston rings was assumed,

Insuﬃcient ship

why was an overhaul of the pistons not carried out immediately?

management
Insuﬃcient ship

There was no guideline.

management

Measures

Methods＜＜ Establish guidelines and ensure compliance with crew on ship ＞＞

Thorough instruction

When it is deemed necessary to carry out an overhaul because of an abnormality,

Thorough ship manage-

make a request to the administrator immediately.

ment and supervision

Time-sequence ⑤

Not realizing abnormality within the engine

The main reason for burnout was a lack of LO, but it was in fact caused by the dropping-off of a snap ring. A description of the mechanism that controls LO and how this causes the oil to not flow smoothly, as a result of a snap ring
dropping off, is as follows. (See Fig. 43)
The main engine No.4 cylinder on the 28th of March, 2013 was as follows.
(1) Piston Skirt
Time-sequence (2) Piston Pin Boss⑤
(3) Snap Ring
(4) Cylinder liner: severe seizing and broken damage at the bottom of oil ring
: broken damage at the bottom in entire circumference. There was acontact mark from the piston pin on the fore side.
: breakage to the centre and dropped oﬀ. There was no contact markin the gutter insert.
: existence of vertical scratch damage (two lines).

The causes are presumed as follows.
(1) The cause of burnout was down to a lack of cooling oil in the piston.
(2) Strength deterioration by piston skirt overheat.
(3) The snap ring on the bow side was not set correctly.
(4) The snap ring had dropped-oﬀ and the piston pin moved to the same direction.
(5) Both left and right sides of the piston pin made contact with the liner on the bow side
and caused vertical scratch damage.
As a result, the following were caused.
Due to the dropping-oﬀ of a snap ring, there was a shortage of piston pin cooling oil.
Furthermore, as a result of the shortage of piston pin cooling oil, it caused overheat, strength
reduction and broken damage to the liner.

− 55 −

Errors

Related problems

1

The insuﬃcient awareness of the inportance of piston assembly by
the engineer in charge.

2

Lack of risk prediction of 'engine trouble may be caused if snap ring is
not correctly inserted'.

3

Regarding assembling equipment which may lead to an accident, why
did he not instruct the manufacturer to pay attention to assembly
work or inspect the work that was being carried on board at that time?

4

There were no opportunity for training and on-ship guidance.

Insuﬃcient ship
management
Crew's insuﬃciency ofworking skills
Insuﬃcient ship
management
Insuﬃcient ship
management

Measures

Methods＜＜ Thorough crew training ＞＞
The essence of the accident is 'how to understand the basic structure of apiston and what kind of accident can be predicted in the case of insuﬃcientmaintenance'.

Crew training＜＜ Thorough guideline creation ＞＞
Thorough ship
Regarding the parts which may lead to an accident occuring because of failure ofmanagement andmaintenance inspection/assembly, and 'working instructions to the shore worker orsupervision

watch on the ship's work site'(a) As described earlier, the piston pin(full floating type) is inserted into
the piston pin boss. The snap ringis inserted into the gutter of bothends of the boss.
(b) Therefore, if the ring gets separated, the pin will move toward theaxial direction. Thus, the passage
of LO gets blocked by the shiftingof the positions between the oilhole of the connecting rod and thefilling hole of the piston pin.

Snap Ring Missing

Snap Ring
Piston Pin

Piston Pin Moved(c) As a result, the filling oil to theupper part of the piston pin bossand piston cooling space will be
stopped.

(a)Snap ring at normal
Fig. 43(b)Snap ring when dropped-oﬀ

Prevention of LO Flow which Aids Piston Pin Movement− 56 −

§4-3-2 Case ②

Crank Pin Bearing Damage Accident

The error chain of Case ② ‘crank pin bearing damage accident’ was analysed according to time-sequence.

Time-sequence ①
Timesequence

Crew’s lack of awareness regarding the important points of piston assembly.

On the 4th of October, 2010 Main engine No.7 Cylinder piston draw-out by the crew①
ErrorsRelated problems

1

The insuﬃcient awareness of the inportance of piston assembly by
the engineer in charge.

Crew's insuﬃciencyof working skills

2

Lack of risk prediction which 'may develop to engine trouble, if
connecting rod was tightened incorrectly'.

Crew's lack ofknowledge

3

Why was there no opportunity to take internal training?

Insuﬃcient crew
training

Measures

Methods＜＜ Reinforcement of crew training ＞＞

Crew training'Allow the crew to learn about the basic structure of the connecting rod andeducate them as to what kind of trouble may occur in the event of maintenance
failure', which is at the root of the trouble.

Thorough ship
management andsupervision

All error chains derive from the crew’s insufficiency of knowledge and operational skills required for important
maintenance.

Time-sequence ②
Timesequence②

Lack of knowledge regarding how to tighten bolts

When the accident occurred on 28th October in 2011, the condition of main engine
No.7 cylinder was as follows:● Two connecting rod bolts broke at the large end of the stud bolt.
● The other two bolts were bent in the middle
ErrorsRelated problems

The crew was not familiar with both the tightening technique andthe inspection method.
● Technique of tightening based on the manufacturer's

1

instruction manual (torque, angle, hydraulics)● Handling a torque wrench (precision, setting and correction)

Crew's insuﬃciency ofworking skills● Carry out correct assembly of each part, inspect nut andbolt surfaces and penetration test of crank pin bolt before
tightening.

2

Insuﬃcient ship

No maintenance guidelinemanagement− 57 −

3●●

Why was the senior engineer negligent to conﬁrm the importantInsuﬃcient work

points regarding connecting rod assembly?

instructions, etc.

Measures

Methods＜＜ Thorough guideline creation ＞＞

Thorough instruction

Regarding connecting rod assembly, 'tightening technique, handling ofa torque wrench, parts assembly and cleaning the surfaces of nuts, andpenetration test of tightening bolts etc.'

Thorough ship
management andsupervision'Items that the senior engineer must conﬁrm' when maintaining a vessel.

Although crew should have been familiar with the ‘technique of tightening and the inspection method of the crank pinbolt, which were referred to in the manufacturer’s instruction manual’. But they could not have done this.
The crew must assemble each part so as for them not to come loose with centrifugal force and vibration during engine
operation. That is why it is important to understand the following regarding the technique of tightening and the inspection of bolts.

（a）Technique of tightening based on manufacturer’s instruction manual(torque, angle and hydraulic jack)Technique and force of tightening are stipulated in the manufacturer’s instruction manual. The crew must tighten theblots evenly based on the instructions. At that time, it is necessary to pay attention to each tightening unit.
＜ Remarks on bolt tightening method ＞● Not to make a mistake in the technique of tightening using several different methods.
● Torque method (N・m or kgf・m), angle method(°), torque ＋ angle method (tightening in two stages),
hydraulic jack method (MPa or kg/cm2), etc.,＜ Having disassembled the connecting rod and having newly replaced crank pin bolt remarks ＞● Carry out re-marking of the Set Mark when assembling.
● Check for bolts and nuts that may have worked loose following a certain operation hours after theassembly. (For example: inspect the position of the Set Mark and re-tighten to the specified torque)(b)

How to handle a torque wrench (precision, setting and calibration)

In torque method, a torque wrench is used for tightening bolts. The wrench has the following features. Crew must
understand how the wrench works and handle it appropriately.
● Set the control value correctly for the wrench.
The unit should be noted:（[N・m] value ＝ [kgf・m] value × 9.8, [kgf・m] value = [N・m] value × 0.102,
For example, 49N・m = 5kgf・m）●

Crew must treat the wrench carefully as a precision-tool in order to maintain precision.

Also, the following are required for safekeeping of the wrench.
●

The wrench is to be stored separately from other general tools.

●

The setting point should be set to the minimum level.

●

The wrench should be calibrated regularly or replaced with a new one.

− 58 −

（c）

Assemble correct parts, clean and inspect nut and bolt surfaces before tightening

Before tightening, it is a must that the surfaces of nuts and bolts are thoroughly inspected and cleaned, together withcorrect assembly. For example, crew must tighten after inspecting and cleaning of the seat surface of the large end
and the bolt head and nut. If crew neglect to clean, dust will gather. This will cause the nut to end up in a ‘loosened
state’, because such dust stuck in a specific area deteriorates the tightening force of the nut and bolt then exposed tocentrifugal force and vibration due to the rotational motion of the crankshaft during engine operation.
As a result, the large end will detach from the crankshaft which has a danger working free. In addition, roughness andscratches on the seat surface of the bearing will reduce bearing contact surface area. If nuts and bolts are unevenly
tightened, a similar problem will occur. Therefore, the inspection of the seat surface is also important.

（d）

Dye penetration inspection of the bolt (non-destructive inspection), etc.

As the bolt receives repeated stress during engine operation, the strength is reduced each year. Then, at the time ofdisassembly and maintenance, crew must inspect to see if there is any damage on the metallic surface by Dye Penetration Inspection. If any damage is found on the bolt, it has a danger of breaking.
Note: Dye Penetration Inspection is also referred to as colour check. This is a non-destructive inspection method which detects
cracks that appear on the surface of the material, by using a red or fluorescent coloured penetrant; with the usage of thecapillary action principle.

（e）Handling precautions regarding the bolt

In this case, the bolt itself was broken. Thus, in addition to the tightening method, durability management requires
special care. The points are: dye penetration inspection (non-destructive inspection described above in (d)), dimension
measurement (evaluation of bolt extension), maximum hours of use (bolt life management), etc. The necessity ofdye penetration inspection is mentioned above. Moreover, crew must be able to recognise the extent to which thebolt extended by measuring and recording the length of the bolt. In this case, compare it with a spare new one. Also,
maximum hours of use of the bolt is described in the manufacturer’s instruction manual. It must be replaced basedon this. For example, 20,000 hours of maximum use, is roughly equivalent to 3 years when annual operation rate
is approximately 80% (equal to around 7,000 hours per year). Therefore, the bolt must be included in maintenanceschedule as an essential spare part.
＜＜ Reference Information ＞＞
Nippon Kaiji Kyokai Summary of Damage Generator Engine's Connecting Rod Accident.
The previously mentioned ‘accident’ occurred in the main engine of a 4 cycle diesel engine. Class NK showsa ‘Summary of damage’ in their bulletin annually. In their bulletin, Class NK issued a detailed warning notice
regarding the above accidents which occurred in the generator of the same type of engine (4 cycle diesel engine).
(They posted in the bulletins No. 292, 296, 301, 304, 309 and 312 from fiscal year 2009 to 2014) . The pointsof the above accident are summarized below, with reference to their bulletin. The number of annual average for
accidents that were clearly caused by crank pin bolt breakage (including looseness and dropping-off) accounted formore than 60%.
Crank pin bolt breakage is mainly caused by incorrect tightening during assembly of piston by crew. The mechanism is as below:− 59 −

When the engine is in operation, inertia force of the piston interacts with the large end of the connecting rod. Atthat time, if the bolt is insufficiently tightened, it will work loose. As a result, the bolt will break and the nut will
drop off respectively.
The causes of insufficient tightening of bolts are mainly as follows:①

It was tightened with an insuﬃcient torque.
Although the bolt was tightened by a prescribed torque, this was insuﬃcient for thefollowing reasons:②（a） Failure to notice a rough seat surface. However, it was tightened as it was.
（b）

Failure to notice cracking at the part of the serration on the large end of theconnecting rod. However, it was tightened as it was.

‘Angle tightening’ as opposed to ‘torque tightening’ is indicated by the engine manufacturer. The reason is
because it can be tightened with greater precision.
Moreover, there is another large reason for breakage of the crank pin bolt. It is deterioration in strength of the bolt
itself. It is caused by the continued excessive hours of use of a bolt beyond the limit recommended by the engine
manufacturer. A measure is to carry out maintenance based on the instruction manual and service news updates.

§4-3-3 Case ③

Oil Spill Accident

The error chain of an ‘Oil Spills Accident’ (Case ③ ) was analysed by time-sequence. Error chains were caused byboth breach of work in accordance with work instructions and crew’s lack of operational skills and knowledge.

Time-sequence ①
Timesequence①

Failed to check for remaining oil of final top-up tank

At previous port, 2/E was allocated to measuring work of the remaining oil in thetopping up tank (No.3 FO tank), but he did not do it.
ErrorsRelated problems

1

Did the 1/E accurately explain to the 2/E the work plan timetable, work
allotment, procedure and the importance of the task at the meeting
before duty? Could the 2/E grasp it?

2

Did the 1/E not conﬁrm with the 2/E in the meeting that the work had
been completed?
Was there not bad communication between the 1/E and 2/E?

Daily duty
management

Daily duty
management

Did not the 2/E have more important work which was a priority?

3

If he had, why did not the 2/E ask the 1/E for a change of assignment?
Did not the 1/E grasp the 2/E's work responsibilities?
Could not the 1/E rearrange the 2/E's work with other personnel?

− 60 −

Daily duty
management

4

Were not remarks regarding the danger, when there was an error ofmeasuring remaining oil, described in the work instructions?
Could the 2/E grasp it?

5

Could not the 2/E predict the risk of trouble through failing to measure
the remaining quantity?

Work instruction
relatedRecognition ofdangerMeasures

Methods＜＜ Reinforcement of crew training ＞＞

Crew training

Daily duty management (planning, assignment, communication regarding actual

Crew training

duties, and inappropriate responses towards more important work to be prioritized)
Work instruction related (remarks missing regarding the danger of making a mistake
when measuring remaining oil)

Crew training
Recognition of danger (insuﬃciency of risk prediction towards the trouble which
may be caused by failure in measuring the remaining oil in the tank)Time-sequence ②

Breach of procedure

Because items to be checked was not conducted, breach of procedure was raised as a problem.
Timesequence②

Made a plan assuming that there was no remaining oil in the topping up tank,despite not having carried out measuring of the actual remaining oil amount.
ErrorsRelated problems

Did the 1/E accurately explain to the 2/E the work plan timetable,

1

work allotment, procedure and the importance of the task at themeeting before duty?

Daily duty
management

Did the 2/E understand it?
The 2/E did not carry out remaining oil measurement.

2

However the 1/E made the bunkering arrangement plan document,
assuming no oil remained. What is the reason for this?

3

Was the 1/E competent for the duty allocated in the assignment ofroles?

Fig. 37 Work instructions
Lack of information of
A-aFig. 37 Work instructions
Lack of information of
A-a

Measures

Methods＜＜ Thorough guideline creation ＞＞

Thorough instruction● Daily duty management (conﬁrmation)

Thorough ship

● Work instruction related（making a bunkering arrangement plan document

management andand an allotted list for bunkering arrangement work sharing)− 61 −

supervision

Time-sequence ③

Breach of plan

Work instructions were not considered during making the plan.
Timesequence③

Make a plan at a target level which is equivalent to 66% of the tank capacity(approximately 62KL) (this is related to Time-sequence ⑤）
Errors12

34

Related problems

Work instructions

Were the crew able to acquire the method and an understanding of
the state of the topping up tank through measuring the tank regularly
during bunkering?
Did the 1/E understand the various calculation methods (inflow
quantity(㎥ /h）, estimated completion time, etc.)

Work instructions

Could the 1/E obtain the calculation method for predictive adjustment of the ﬁnal liquid level of the topping up tank, having measured
the liquid level of the tank which completed receiving oil.
Did the 1/E make plans to double-check the system for measuring
the liquid level of all tanks?
(Appropriate personnel arrangements)

D-a
Table 38
Work instructions
D-a

Thorough ship
management andsupervision

Although the 3/E and two oilers measured the actual remaining oil quantity in thetank just before the start of bunkering, they did not realize the quantity.
Related problems

Why did the 3/E not notice the remaining oil before thecommencement of bunkering?

Table 38
Work instructions
D-a

Who was the person responsible for calculating the remaining oil

2Work instructions

The remaining oil measured was not precise.

Errors1

Table 38

Thorough instruction

work allotment)④

D-a＜＜ Thorough guideline creation ＞＞● Work instruction related (appropriate bunkering work sharing and list of

sequence

Table 38

Methods

measurement: remote level gauge, actual measurement (sounding scale)

Time-sequence ④

A-c

Measures● Work instruction related (grasp of bunkering progress and regular tank level

Time-

Table 37

How reliable was the remote level gauge for the topping up tank?
(Did the 1/E conﬁrm if it may be useful to grasp the liquid level bychecking normal operation and indicator prior to bunkering?

quantity? The chief engineer or the 1/E?
Did the engineer in charge of calculation of remaining oil quantity
understand the calculation method?

− 62 −

Fig. 37
Work instructions
A-a, b, c

3

Did they correctly obtain the necessary environmental information

Table 37 and 38(temperature, trim, etc.,) for calculating remaining oil quantity andWork instructions

data (speciﬁc gravity & volume conversion factor, etc.)?
Did the chief engineer check the statement of re-calculated planning４

immediately before bunkering that was formulated by the 1/E?
Was a ﬁnal meeting immediately before the start of bunkering held?

A-c, C-a, D-a
Table 37
Work instructions
A-a, b

Measures

Methods＜＜ Thorough guideline creation ＞＞

Thorough instruction● Work instruction related（measurement of all tanks, work sharing,Thorough ship manage-

calculating the remaining oil and supervision by superintendent)

Time-sequence ⑤
Timesequence⑤

Did not stop oil transfer despite the occurrence of an overflow

The 3/E and two oilers (who measured the liquid level continuously) did not stop
oil transfer even when it exceeded the planned top-up level during bunkering,which caused overﬂow from the air vent.
Errors1ment and supervision

Related problems

Why did the 1/E not stop even when it was beyond the top-up liquid
level of the plan?
● Did the 3/E and two oilers actually measure the tank regularly
during bunkering and report to the 1/E?
● Did the 1/E check the diﬀerence with the liquid level, by conﬁrming the tank during bunkering by remote level gauge regularly?
● Did the chief engineer have a grasp of the ﬁnal situation justbefore completion of topping up?

Table 37

Work

instructions
C-a, D-a

Did the 1/E correctly calculate the top-up liquid level of all receivingtanks in advance?
● Safe work and action cannot be ensured, if top-up liquid level ofeach tank is ﬁxed at the time of making a plan.

2● If the liquid level of the tank after bunkering is diﬀerent to the plan,
the ﬁnalized liquid level of the topping up tank must be adjusted.
Did the 1/E conduct the correction calculation method?（PDCA）

Table 37

Work

instructions
A-a● If the liquid level of the previously completed tank is less thanthat of the plan, the liquid level of the topping up tank will behigh. Did they not consider this to be dangerous?

3

Did all workers understand the ﬁnal liquid level to be topped up?
● Anyone could notice something unusual and oﬀer an opinion.

Table 38

Work

instructions D-a

Measures

Methods＜＜ Thorough guideline creation ＞＞

Thorough instruction● Work instruction related（bunkering arrangement, estimate the liquid levelof the receiving tank, inform those around and monitor the situation）− 63 −

Through ship management and supervision

Time-sequence ⑥
Both chief engineer and the 1/E did not have a firm grasp of the amount of oil in the final topping up tank.
Timesequence⑥

Overflow: When the accident occurred, 96% of tank capacity (approximately 91KL)
had been pumped into the topping up tank. There was no problem regarding
bunkering work on the barge side (agendas in the pre-meeting, oil transfer quantity,
total amount of oil transfer, etc.)
Related problems

Errors1

2

Did the chief engineer and the 1/E recognize that the topping uptank had been ﬁlled to 96% when it began to overﬂow.

As to what percentage did the chief engineer and the 1/E recognize
the liquid level of the topping up tank to be at that time?

Table 38

Work

instructions
D-aTable 37 and 38
Work instructions
A-a, b, D-a

Measures

Methods＜＜ Thorough crew training ＞＞

Crew training● Work instruction related（grasp of the bunkering quantity before topping

Thorough ship manage-up, tank liquid level and quantity adjustment before completion of transfer）

ment and supervision

Time-sequence ⑦
Timesequence⑦

Delayed emergency stop

The 1/E (who is responsible for bunkering work and contact liaison with the barge)
delayed in emergency stop measures, following overﬂow.
ErrorsRelated problems

Is there an emergency procedure instruction manual on board?
１

Handling of it ? Recognition of it ?
●Fundamental code of conduct that the vessel is to maintainunder SMS and safety management manual

２

３

４

Did all crew recognise 'accident impact in the case of neglecting
emergency actions'?
Did all crew attend an emergency procedure instructions workshop
in advance?

Had all crew conducted emergency drills at the time of overspillage?

− 64 −

Table 37 and 38
Work instructions
A-b, C-a, D-a

Recognition of danger

Safety training
Safety management codeandtraining in the case ofan emergency

Measures

Methods＜＜ Thorough guideline creation ＞＞

Thorough instruction● Work instruction related（emergency procedure instructions）＜＜ Reinforcement of crew training ＞＞●

Thorough instruction
Crew training

Recognition of danger (Accidents that escalate when emergency response isinappropriate)●

Safety training (enthusiasm towards emergency procedure instructions)

Crew training● Safety management code (Making a plan and implementation of emergency drills)§4-4

Analysis with an ETM (Engine-room Team Management) Overview

Just as with Bridge Team Management (BTM), Engine-room Team Management (ETM) is a functional organizedsystem that utilises mutual communication between not only those such as chief engineer, engineer and engine
department crew, but also between software (SMS manual and safety management code, etc.), hardware (equipment)
and environment (external information).
As indicated in each table under ‘§4-3 Accident analysis along with the error chain’, the problem is ‘Why wassomething unusual (‘foresight’), which caused trouble from daily monitoring situations of equipment allocated in theengine room, not discovered?’ Or, ‘Why was there not the effective function of the ‘human five senses’ in order toshed light on the problem?’
The cause was down to a lack of basics regarding engine watch. As was introduced in the ‘collision accident’ cases,
the most important aspect of operation in navigational watch is ‘look-out’. Although it is emphasized that it is important to taking a quick and dynamic approach towards a dangerous situation at sea, the same applies to engine watch.
In other words, the fundamentals of engine watch is for the crew to collect and analyse difficult to detect information
via remote monitoring sensors, and by ‘utilizing the superior human senses during engine room round watch’.
Furthermore, crew is required to take the necessary actions.
Engine-room Team Management (ETM) Analysis
Compliance Rules

Problems
Piston seizing, Piston skirt broken damage

Constant operation information and adjustment of main
engine and auxiliary machineryand equipment (temperature,pressure, consumption andthose changes)①

Main engine LO consumption increased from around June, 2012.
Although consumption increased by approximately three times
to that of normal condition just before the accident, there wereneither inquires made to the manufacturer nor particular actions
taken, regarding the abnormal consumption of LO.

②

Were signs of abnormality not noted until the day prior to when thetrouble occurred? How had the temperature of LO and the pressurechanged? Was there an abnormal noise, or an overheated casing?

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Appropriate Planned Maintenance System: maintaining
the state of equipment that
performs to the design specification.

①

Was the piston maintained in a planned manner?

②

Because the item was replaced with a remodeled part, they
trusted the overhauling and assembly entirely to the manufacturer.
Assembling work was not conﬁrmed on the vessel side.

Education on the ship: establishment of common recognition regarding the engine system.

①

Regular study session
workshops about
engine operation andits procedure with theoperation management
system.

①

As LO consumption increased by approximately three times to thatof normal, the inside of the crankcase was inspected. However,there was no abnormality found and it was thought that the pistonrings were worn.

②

Information sharingof trouble cases andexperiences①

Risk prediction was not recognized. What kind of accident was
expected, in the event of insufficient maintenance of the basic
structure of the piston?

①

There was no guideline for points to be checked such as important
procedure for assembling, timing regarding watch on the ship's worksite and the necessity of asking for assistance from the vessel' for
manufacturer's repair work.

②

There was no guideline for inquiring after the manufacturer foradvice and emergency measures to take in the case of discovering
an abnormality on the ship.

③

Because some parts such as a snap ring may cause an accident due
to damage, a guideline and a checklist on issuing an instruction
to manufacturer worker or watching out for abnormalities in the
ship's working areas for inspection maintenance and assembly are
required.

④

There was no guideline on making a request to the ship superintendent
immediately, if overhaul due to abnormal prediction was found to benecessary'.

⑤

Did they share information in more casual circumstances (i.e. during
recess)?

③

Workshop based on themaintenance procedureand its risk assessment

Crank pin bearing damage accident
Constant operation informationof main engine and auxiliarymachinery and equipment (temperature, pressure, consumption
and those changes)
Appropriate Planned Maintenance System: maintaining
the state of equipment that
performs to the design speciﬁcation.

①

Were signs of abnormality not noted until the day prior to when
the trouble occurred? Was there abnormal noise, or an overheatedcasing?

①

Carry out overhaul inspection based on the planned maintenanceschedule.

②

There must have been a description regarding the technique oftightening in their instruction manual.

− 66 −

Education on the ship: establishment of common recognition regarding the engine system

①

②

③

Information sharingof trouble cases andexperiences

Workshop based on themaintenance procedureand its risk assessment①

There was no recognition of 'if the connecting rod is tightenedincorrectly, that it may develop to engine trouble'.

①

There is no maintenance guideline regarding 'tightening techniques,
handling of a torque wrench, parts assembly and nut surface
cleaning, penetration test when tightening bolts, etc.'②

There was no safety guideline for 'items that the senior engineer
must conﬁrm' when maintaining a vessel.

①

Was the utilization of the ﬁve senses to detect something amiss at
the time of round inspection understood?

②

Did they share information in more casual circumstances (i.e. during
recess)?

To utilize ﬁve senses

Oil Spills Accident
Education on the ship:
establishment of common
recognition regarding
bunkering①

Breach of procedure②

Insuﬃcient communication③

Lack of risk prediction
Table 44 ETM Analysis§4-5§4-5-1Preventive Measures

Relationship between Accidents and Causes

In the above described cause analysis, the common causes are emergent in ‘ETM’ respectively. Firstly, the relationship between cause and accident, though basic, is the main focus.
In Table 45, ❶ cause investigation flow, tracking back from the accident result, is shown. The accident causes can beroughly divided into ❸ a direct cause, which is directly connected with the accident and ❹ indirect cause, which isthe surrounding circumstances behind it. And, the causes in the background can consist of ❺ human indirect causesand ❻ root causes led by insufficient control of the organization. It will be difficult to prevent a similar accident, until
the indirect causes related to human error, which are shown in flowchart ❺ and ❻ , including root causes hidden in❻ , are eliminated.

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❶

Consequences：Impact caused by an accident
Number of concerned people (injury or death), compensation forproperty damage, spilt quantity, damaged areas, black-out hours,
business disruption, loss amount, etc.

❷

Accident/Trouble
Equipment damage, black-outs, oil (bilge) spillage, air pollution, falls, etc.

❸

Direct Cause：Clear reasons
Dangerous action (Disregard for safe working practices, not wearing safety
equipment), dangerous situations（dark, noisy and harmful or explosive situations)❹Indirect Cause： Reasons underlying backgroundinﬂuences of direct cause
It may be the case that this cannot be proved, even if it wasinvestigated.

❺

Human Indirect Cause：
Human error： Human factor（lack of experience, etc.) andWork factor（i.e., sleep deprivation and fatigue)❻

Root Cause：Insuﬃcient management
Lack of planning, insuﬃcient procedure, standard and guideline,
lack of compliance, etc., even equipment design error.

Fig. 45 “Relationship between Trouble and Cause, and Cause Investigation Flow”

Each of those accidents that apply to this flowchart will be shown in Tables 46, 47 and 48.

− 68 −

Case ①

Piston burnout and piston skirt broken damage accident

Items

Details❸ Direct cause

The route for supplying lubricating oil was blocked and the piston overheated.
Subsequently, the piston skirt sustained broken damaged due to the piston seizing in
the cylinder liner. As a result, the cylinder liner and crankcase door was damaged.

❺ Indirect cause①

There was no recognition of risk prediction, for example, that 'engine trouble
may have developed if the snap ring had not been correctly inserted'.

②

At the time of inspecting the inside of the crankcase 'not only should
contaminants at the bottom (metal pieces of bearings, combustion residue,etc.) be observed, but also the state of the piston and liner'.

③

Could not recognise the signs of an accident by round inspection?

The following guideline was not established.

①

Guideline of points to be checked 'such as important procedure for assembling,timing regarding watch on the ship's work site and the necessity of asking forassistance from the vessel for manufacturer's repair work.

②

Guideline 'for inquiring after the manufacturer for advice and emergency
measures to take' in the case of discovering an abnormality on the ship.
In the guideline, the necessity of being able to adjust the piston location in theevent of inspecting the liner should be added.

❻ Root cause

Because some parts such as a snap ring may cause an accident due to damage, a③

guideline and a checklist of 'working instructions to the shore worker or watch on
the ship's work site' for inspection maintenance and assembly are also required.

Table 46

Case ②

Cause Analysis (Piston Seizing, Broken Damage in Piston Skirt Cases)

Crank pin bearing damage accident

Items

Details❸ Direct cause

Due to breakage of the connecting rod bolt, the large end of the connecting rod was
released and the connecting rod passed through the crankcase door, which disabled
the main engine operation.
①

There was no recognition of risk prediction that 'if the connecting rod wastightened incorrectly, that it would develop to engine trouble'.

②

Could not recognise the signs of an accident by round inspection?

❺ Indirect cause

The following guideline was not established.

❻ Root cause①②

Regarding the assembly of the connecting rod, guideline for maintenanceof 'technique of tightening, handling of torque wrench, parts assembly andcleaning the surfaces of nuts, penetration test of the bolts, etc.'
Safety guideline of 'items that the chief engineer and the 1/E must confirm'
when maintaining a vessel
Table 47

Cause Analysis (Cause Analysis Cases)− 69 −

Case ③

Oil Spills Accident

Items

Details❸ Direct cause

Delay in emergency stop measures by the 1/E following overflow. The 1/E is
responsible for bunkering work and contact liaison with the barge.
Technical knowledge insuﬃciency①●

Method of measuring the tank liquid level●

Calculation method of remaining oil in tank (bunkering quantity)(Implementation of trim heel correction by tank table)

Lack of safety and environment awareness❺ Indirect cause②●

Superintendent's awareness of safety and environment●

1/E, 2/E and 3/E's recognition of danger (risk prediction)● An accident that is expected to occur when tank measurement is not suﬃcient●

Accidents that are expected to escalate when emergency response is inappropriate●

Safety training related: enthusiasm about emergency procedure instructions.

●

Safety management code related: Making a plan and implementation of
emergency drills

The following were insuﬃcient regarding work instructions for bunkering.
●

Remarks before bunkering plan: measurement of remaining oil●

Remarks when making bunkering plan:⒜ Bunkering plan (ensure more than 10% of tank space for topping up = plan
not to ﬁll more than 90% of tank capacity)⒝ Work sharing (personnel arrangements) and estimation of receivable tank level⒞ Supervise by superintendent and double-check●

Remarks before bunkering work:⒜ Meeting for information sharing on bunkering plan①⒝ Reconﬁrmation of countermeasure in state of emergency❻ Root cause●

Remarks before receiving: measurement of all tanks, work sharing, calculationof remaining oil and supervision by superintendent●

Remarks during bunkering: regular measurement of tank level (remote level
gauge, actual measurement (sounding scale))●

Remarks at the time of topping up the tank: grasp of receivable quantity
and tank level●

Emergency procedure instructions(There is a high possibility that spillage into the sea could have been
suppressed, had the 1/E taken action immediately at the time of the overﬂow.)

Insuﬃcient routine work②●

Failure of, inadequacy and/or lack of information sharing regarding reportingand conﬁrming of plan, manning and practice, and plan changes (if applicable).

Table 48

Cause Analysis (Oil Spills during Bunkering Cases)− 70 −

Considering the analysis of events with a viewpoint from the PDCA cycle (Plan, Do, Check and Action), the key pointis that ‘Safety can be defined as the result that avoids risks’ as explained in Chapter 2. In the case of engine relatedtrouble, Plan is associated with work instructions and guidelines which were created based on the manufacturer’s
instruction manual, work analysis, experimental rule, past lessons, principles of natural science and various kinds oftechnological information, etc. This technology is not simply summarised into work instructions. Extracting the fundamental risks assumed in each duty in advance, manageable measures will be introduced following analysis in orderto reduce the risk level. In addition, the risk level will be reduced, if everyone clearly understands work instructions
and guidelines of risk management (human factors) and practices it accordingly. However, if there is a lack of humanexperience and fatigue, the risk cannot be reduced because it is not possible to ‘Do’ (or) follow work instructions or
guidelines accurately. No matter how bad the outcome, risk cannot be avoided. Elements of human behaviour standbetween the fundamental plan and the end result. Therefore, when thinking about cause categories, it is an indirectcause that a human cannot execute.
Let’s compare daily duties or services on the ship to a drama. We exemplified daily duties on a ship using role play(drama). Work instructions and guidelines can be replaced with scenario (Plan) and the crews’ behaviours with theactors’ performances on the stage respectively. Even if the scenario is poor, once splendid actors perform (Do) andovercome the poor situation, it in turns into a masterpiece. However, it is hard for the ship owner and ship manager
to allocate a superstar (a noted member of crew) to always perform. In order to encourage the actors to perform better
than a certain level, it is important to prepare a wonderful (attractive) scenario to support them.
Meanwhile, accident analysis is Check (evaluation) and preventive measures are Action (improvement). Moreover, it
will be ideal, if the Plan can be improved so as to better verify as to whether the preventive measures are functioning
effectively.
However, following accident occurrence, the person involved tends to focus on the direct cause, which is easy toactualize generally. Because of this, symptomatic measures are often taken. This can be applied to the ‘grave-post
type’ of safety measure which was explained in the ‘Loss Prevention Bulletin: Thinking Safety (Vol.35)’; and that thiskind of symptomatic measure can cause another similar accident.
It should be emphasized that preventive measures should be introduced following the digging up of the root cause(‘preventative type’ of safety measure). Therefore, first of all, events prior to the accident should be specified and,then, the cause can be extracted by analysing as to why each time-sequenced event occurred. And, finally, preventive
measures will be led by examining ways to eliminate the cause.
In ISM Code 2010 amendment, the following is specified: 1.2.2. It should assess all identified risks to its ships, personnel and the environment and establish appropriate safeguards; and 9.2 The Company should establish proceduresfor the implementation of corrective action, including measures intended to prevent recurrence. Because of this, it ispresumable that both risk evaluation and the scheme for preventive measures are established in the SMS manual at therespective companies. Please take a look at it.

− 71 −

§4-5-2

Preventive Measures

Summarizing the root causes of Cases ① , ② and ③ , an accident could be caused, because the following items wereinsufficient. In all stages, it is required that work instructions and guidelines be equipped, to perform thorough crew
training and to observe the prepared guidelines and work instructions strictly.

①

Conduct the maintenance and inspection based on the manufacturer’s
instruction manual②

Replace parts in accordance with the standard③

Confirmation of critical points regarding the process of maintenance andrepair assembly④

Watch-keeping that utilizes the human five senses⑤

Understand the relationship between the basic structure of equipment andtrouble⑥

Maintenance of work instructions and guidelines⑦

Thorough crew training

Regarding prevention for accidents related to the engine including Oil Spill Accidents, the following items areespecially important.

Maintenance

The systems and equipment on the vessel must operate normally as designed basedon the principles. Therefore, the crew is expected to maintain and inspect the above
in a planned manner everyday. The measure is for the ship manager to establish‘a system that has guidelines and a thorough method of instruction’ as a Plan. For
example, the guideline requires PMS (Planned Maintenance System), work instructions,guidelines for maintenance and a work check list.

Monitoring of
the condition

The system and equipment on the ship is operated under a variety of conditions.
Thus, the crew must clearly understand those different operating states on a daily
basis. If they can recognize an abnormality at an early stage, appropriate measures
can be timely taken. Therefore, the measure is for the ship manager to establish the‘basics of engine watch’ in order for the crew to be able to Do (practice). For example,
enforcement of daily inspection and safety education.

EducationsystemThe crew are expected to understand trouble related to the basic structure of theabove. Thus, in order for the crew to practice (Do) it, it is important for the ship
manager to establish a ‘maintain and improvement system of knowledge level = theeducation system’. For instance, regarding the system and equipment, it is to reeducate the fundamental items and structure and hold a case workshop. These weresummarised in the Table 49.

− 72 −

No①

M easures

Key points of
̀E TM'

̀Planned Maintenance
System (PMS)/Work instructions/
Maintenance guideline/Work checklist'

MaintenanceMonitoring thesituations

Insufficient items
Performance of maintenance andinspection based on manufacturer's
instruction manual②

Part replacement in accordance with thestandard③

Conﬁrmation of important phase in theprocess of maintenance, recovery andassembly④

Round inspection utilizing ﬁve humansensesDaily inspection and safety
training⑤

Understanding the relationship between
basic structure of appliance and trouble

Re-education of basic items
and structure

Table 49

Education system

Summary§4-6 Proposals for Vessels with a Tight Operation Schedule
It is also essential to try to ensure the quality maintenance of vessels with tight operation schedules such as coastal
vessels, ocean going container vessels and PCCs. In other words, operation management is the main issue here due tothe influence of operating time schedules for these vessels. In these circumstances, the crew can only carry out smallscale maintenance during the short staying hours. For example, replacing fuel injection valves on an engine. However,
it is impossible to carry out medium scale maintenance in a short and limited time frame. Therefore, there will
inevitably be more cases of medium scale maintenance by engine manufacturers or ship repairing companies duringberthing. Regarding large-scale maintenance, it is to be carried out by the above mentioned agents during the docking
period. As a result, crews are facing the reality that they cannot be expected to improve their technical skill levels forthese middle and large scale operations, because they have less opportunity and experience of maintenance and also
get less opportunity to earn practical experience.
Therefore, ship managers should pay attention to the above mentioned maintenance background/circumstances andcrew’s technical skill levels. In order to compensate for this, a checklist that includes a summary of remarks for maintenance, inspection and assembly points for each maintenance site will be useful. It is important to make a checklist
like this and perform thorough instruction on the vessel. It is most effective for the crew to make this kind of checklist,
however, it would be an option to outsource this to an engine manufacturer or technical consultant.

− 73 −