Chapter 4: Knowledge Base for Chief Officer

A chief officer at sea is to prepare for the job of captain in maneuvering and responsibility. As a key man on board he also be expected to in charge of major safety of ship’s cargo and structure.  Unfortunately, more than 50 % of marine incident happened at chief officer’s watch for many reasons: 

• o   4-8 watch is most difficult to lookout by eyes due to sunshine from horizon.
• o   The early morning before the sunrise is most sleepy time of the day.
• o   The vessel volume is heavy around the harbour area as all vessels are eagerly to go alongside for 0800 daylight gangs to work.
• o   Master trust Chief with his ability to avoid the danger, but Master may underestimate their physical and mental state to do the watch.
• o   Over confidence at his watch.
• o   Duty AB is cleaning the bridge rather than doing lookout duty.   

For a chief mate we will expect him to handle multiple ships avoidance situation. 

Going to heavy traffic

Fig 4-1 Red Ownship approaching Chang Jiang Mouth L/V COG 100⁰ SOG 12.7 Knots

From paper chart or ECDIS position of ownship, we see the cross road ahead is centered at Chang Jiang Mouth light vessel. What chief should prepare as a competent OOW? Properly set Radar/ARPA/AIS for quick reference as chapter 3: 

Þ   we use X band radar to detect big vessels only by reducing ownship’s radar “gain” setting to smaller. When small target echo are not seen on X band radar, OOW can set ARPA function ”Auto Acquisition”  on. X band 3 cm radar has smaller echo on screen than S band radar.

Þ   we use S Band 10 cm radar to detect smaller target at close range due to its echo size is bigger and rain or sea clutter won’t deteriorate it reflection quality. OOW will need to reduce the detection range to 3 nautical miles or off centered to allow 5 nautical miles ahead. When OOW well adjust radar to detect small targets around ownship, target speed vector and trail should set to relative motion. With relative motion mode ownship can detect whether target has collision risk by Electric Bearing Line to point to target’s bearing to see is it unchanged.    

Beside these two basic settings with two radar, third lookout means by visual or third radar on foremast should be used in these situations to ensure all targets are evaluated by Chief.

After preparing for Radar, we should consider COLREG Rule 20 navigation lights application:  during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out.  Extra lights on deck is allowed as long as it cannot be mistaken for the lights specified in these Rules and etc.…… So, master should decide what lights on deck or accommodation without strong reflection or interfering lookout duty can be used to make ownship more visible at heavy traffic. This decision of lights arrangement should be done before this voyage.  Now lookout just need to switch on the auxiliary lights. SANCHI and CF Crystal did not do this. Extra deck lights can help other vessel to easily distinguish big vessels from numerous fishing boat. It is recommended to do so.  

Fig 4-2 details of radar setting

Radar receiver setting reflect your competence of radar lookout 

Radar as we knew should always in searching mode. Look down on left side of this Radar, 

l  we see the Tuning is automatic setting which is OK. Tune is tuning the receiver frequency to accord with local transmitter oscillator frequency. The reason for this tune is the frequency they said X band or S band is a roughly frequency. The actual frequency range used are‎: ‎8.0 – 12.0 GHz            Wavelength range‎: ‎3.75 – 2.5 cm.  The automatic tuning circuits adjust the receiver frequency to each transmitted pulse. It would be impossible to duplicate this procedure using manual tuning. 

l  we see the Gain is manual setting which is OK: Gain amplifier the receiver echo strength is the most important way in searching mode. Because it is manual OOW will not take the target echo lost as part of his watch, he will adjust the GAIN setting more or less to distinguish the target from the clutter he received. GAIN or other sea rain clutter setting in manual mode has another risk is malfunctioned through no searching mode are made during his watch cause the target echo not shown on screen. To train the OOW of manual adjusting the radar for searching purpose is the responsibility of Captain. Chief officer should be capable of this mentor job too. 

l  We sea rain clutter setting in manual is OK: Sea rain clutter setting should test periodically to ensure it won’t over set so as all target’s echo were eliminated by it. We see target lost in SANCHI radar the sea clutter setting is 40 percent which is too much cause the echo of a big vessel CF Crystal disappeared and 3/O did not know the reason is the sea clutter setting is in auto mode.  

Radar range setting reflect traffic density at the time. If the target number are many we need to reduce the display range to smaller area. If target number too much in left 6 nm range we should reduce radar range to 3 nm. If 3 nm is too much targets we should reduce to 1.5 nm to display. Look up on left side of this Radar,   

l  In figure 4-2 left side we see range setting is 6 nm and the target are numerous. It is over 20 targets of IMO ARPA performance requirement. We don’t need so much target display or target data. Our short-term memory cannot take care of all. In long range, S band radar should be used to scan big vessel echo. So we need to lower the GAIN level to reduce all small target together with sea rain clutter to distinguish big vessel at scene.  X band radar as right side of figure 4-2 had set the display range at 3 nm. These two radars are all set off center of the screen to gain more display distance ahead ownship. This is reflect the undermine of OOW thought target behind ownship has less collision risk than those ahead. X band radar setting is not to leave small target unseen at close range. We see at right side 3 nm radar screen small vessel is very clearly presented on screen. The tune is auto. The gain is about 30%, the sea clutter is 20% and the rain clutter is 0% setting. The tug boat length of 40 meters is easily identify in radar screen.

l  In 3 nm range display the target’s number are controllable but the target’s movement is not clear as we did not see the speed vectors of two target at starboard bow direction. 

l  The reason of this mistake is Master concentrated on big vessel at 6 nm range. Small target at close range did not track or acquired by ARPA. The job assignment of small or big target at Radar screen is not separated. Don’t trust your experiences in everything. Captain still cannot master the skill of radar usage as last chapter. This simple mistake caused the incident of collision in later stage due to radar lookout is not appropriate.

Where is the trail of small vessel we are looking for?  

l  In 6 nm range picture radar trails of the target is not used. So, captain cannot tell the collision risk at first glance as Figure 2-19: Radar echo with trail screen. 

l  Considering the numbers of small target are many and trail is needed in emergency when visual contact cannot establish.

l  Relative motion trails sometimes are very long due to ownship in high speed so as to obscure another target’s echo. 

l  True motion trails are preferable when we need instant information of her movement and most fishing boat are stationary, no movement. In right side 3 nm radar picture the radar trail set to 3 minutes true motion which is shorter than speed vector setting to 6 minutes true motion. 

l  For instant reaction to their movement, the trail length time setting is better to set with same time of our speed vector. We don’t need to double check the trail time setting at emergency. And the speed vector of the small target can be projected mentally to her bow.

l  These trail setting is very useful when target vessel changed course in last few minutes. Ownship can monitor target vessel course within the time interval we set. 

l  Course change is not shown on ARPA graphically, only trail can do this trick.  

Radar speed vector setting reflect collision risk at the time. 

l  The speed vector setting 6 min in this Radar, true motion as easier for ECDIS reference. 

l  The speed vector setting 6 min means we can know collision risk at 6 minutes time. 

l  The speed vector length is like range setting. When targets are many we need to reduce to short time interval to reduce target numbers in question. 

l  When the targets are few, we can set longer time period to find out possible collision position with another vessel.

l  3 minutes speed vector is a minimum requirement for radar lookout purpose as ownship’s ability to avoid collision is limited by this possible collision area.

Figure 4-3 Golden stick to detect collision position at 2230 LT

Golden stick to detect collision position at 2230 Lt

In last chapter we know collision stick is our speed vector. The length of speed vector is set by OOW in searching mode. Set the vector time longer to get earlier warning of collision. Set it shorter to specify the most dangerous target and possible remedy ownship can have to avoid the collision.

In figure 4-3 left picture, ownship speed vector setting is 6 minutes but the target vessel had not set. No collision stick is no radar lookout. So, we show speed vector of this crossing vessel on right side picture as red arrow. The course over ground or speed over ground of the target are not important as OOW did not have the time to remember. 

l  We found one collision spot (red spot) after ownship 6 minutes run and target vessel arrive in the same time.

l  We use Electric Bearing Line EBL to mark target’s bearing on radar with a crayon pencil (the reading is 127 degrees (T). We don’t need the reading but one crayon mark at purple point of picture.

l  The collision time is 6 minutes later by reading the collision position at ownship’s speed vector. What time is not important. In this 6 minute what options we had in hand is important.

• o    Alter course 37 degrees tom starboard side to 127 degrees(T) is available whining 6 minutes.
• o   Reduce speed to half speed is also available to us in 3 minutes time.
• o   Ownship is now in precautionary area of Chang Jiang Mouth L/V. Target vessel may not give way to ownship.