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Chapter 5 Knowledge Base for Chief Officer
第五章：大副的知識庫
海上的大副正為晉升船長做準備，不僅需要培養高階的操船技巧，更要承擔更大的責任。作為船上的核心人物，大副被期望監督與船舶貨物和結構相關的重大安全事項。在航行安全方面，每當船長疲勞或因故無法執行職務時，大副即擔任船長的後備支援。航商公司與全體船員都極度仰賴大副。不幸的是，由於種種原因，超過 50% 的海上事故都是在大副值班期間發生的：
* **4-8 班（早班與晚班）：** 對於目視瞭望而言特別具有挑戰性，因為晨昏的太陽以接近水平的角度反射，直射瞭望人員的眼睛，使其難以發現潛在的危險。
* **日出前的數小時：** 通常是一天中最容易犯睏的時段，這會降低值班人員的警覺性。
* **港口周邊交通繁忙：** 許多船舶急於靠泊，以便讓 0800 上班的日班工人開始工作。此外，完成下午貨務作業的沿海船舶也加劇了航道的壅塞。
* **船長的信任與疲勞問題：** 船長對大副安全航行與避碰的能力充滿信心。然而，作為船上最忙碌的人，大副可能會低估自己在值班期間的身心疲勞，進而影響表現。
* **過度自信：** 對自身值班技能過度自信，可能導致大副忽視潛在風險或未採取必要的預防措施。
* **水手分心：** 值班的資深水手（AB）可能正忙於清潔駕駛台等工作，而非專注於瞭望職責，從而導致對周圍環境的目視監視出現盲區。
對大副的期望是能夠有效處理複雜情況，例如在狹窄水道中避免多船碰撞。傳統上，大副（C/O）負責訓練實習生與初階駕駛員（JO），使其保持對危險徵兆的警覺，並確保他們執行正確的程序來應對此類狀況。駕駛台資源管理（BHRM）的這一部分提供了雷達瞭望技巧，因為這些概念——雖然早在 1950 年代雷達繪圖的早期階段就已被注意到——依賴於基於本船與目標船「真速度向量」（True Speed Vector）的實用原則。這些原則受到自動避碰繪圖儀（ARPA）精度與雷達能力的影響。雖然自動識別系統（AIS）訊號可以提供目標船的真速度向量數據，但作為計算基礎的 GPS 位置，卻因地緣政治問題而進一步受到欺騙（故意偏置輸入）的威脅。這些也是我們在 BHRM 本部分所要探討並致力解決的挑戰。
5-01 進入交通繁忙區域
圖 5-01 紅色本船以航向 100⁰、對地航速 12.7 節接近長江口燈船
在圖 5-01 中，電子海圖（ECDIS）顯示本船位置（以紅線表示）正接近長江口燈船（L/V）。前方是一個以長江口燈船為中心的十字路口。航行值班駕駛員（OOW）應準備哪些符合良好船藝的常規情境意識措施？
**雷達 / ARPA / AIS 設定（如第 3 章所述）**
使用兩套或更多套設定不同的雷達。
* **X 頻段雷達設定（X-band Radar setting）：**
* 若要僅探測大型船舶，OOW 應降低雷達的「增益」（Gain）設定，以從螢幕上消除所有小型目標和海面雜波。
* 當 X 頻段雷達上不再顯示小型目標的回波時，螢幕上將僅保留大型船舶的回波。
* OOW 可以啟動 ARPA「自動捕獲」（Auto Acquisition）功能來自動捕獲大型船舶目標。（注意：與 S 頻段雷達相比，X 頻段 3 公分雷達顯示的回波較小；因此，只有大型船舶才能產生足夠強度的回波以顯示出來。）
* **S 頻段雷達設定（S-band Radar setting）：**
* 10 公分的 S 頻段雷達適用於探測近距離的小型目標，因為它的回波比 3 公分雷達上的回波大，且較少受到雨雪雜波的影響。
* 若要消除 10 公分雷達上的雨雪或海面雜波，OOW 可以降低增益設定。
* OOW 應將探測距離縮小至 3 浬，或將雷達偏心（off-center）設置以提供前方 5 浬的視野。較小的量程設定會放大螢幕上的回波尺寸。
* 當調整雷達以探測本船周圍的小型目標時，請將目標的速度向量（speed vector）和軌跡（trail）設定為「相對運動」（relative motion）。小型目標的相對運動線對觀察者來說更加直觀可見。
* 在相對運動模式下，本船可以透過將電子方位線（EBL）放置在目標的回波上，並根據軌跡的方向檢查方位變化，從而探測到小型目標的碰撞風險。
這兩種方法——使用相對運動速度向量 / 軌跡以及 EBL 設定——允許快速確認碰撞風險，從而在瞭望過程中節省寶貴的時間。
除了這兩套雷達的基本設定之外，大副還應採用其他瞭望方法，例如目視觀察或位於前桅的第三套雷達，以確保對所有目標進行全面評估。如果目標船舶較多，應利用真運動速度向量（後續討論）並結合適當的訓練來釐清整體狀況。
海上的大副正為晉升船長做準備，不僅需要培養高階的操船技巧，更要承擔更大的責任。作為船上的核心人物，大副被期望監督與船舶貨物和結構相關的重大安全事項。在航行安全方面，每當船長疲勞或因故無法執行職務時，大副即擔任船長的後備支援。航商公司與全體船員都極度仰賴大副。不幸的是，由於種種原因，超過 50% 的海上事故都是在大副值班期間發生的：
* **4-8 班（早班與晚班）：** 對於目視瞭望而言特別具有挑戰性，因為晨昏的太陽以接近水平的角度反射，直射瞭望人員的眼睛，使其難以發現潛在的危險。
* **日出前的數小時：** 通常是一天中最容易犯睏的時段，這會降低值班人員的警覺性。
* **港口周邊交通繁忙：** 許多船舶急於靠泊，以便讓 0800 上班的日班工人開始工作。此外，完成下午貨務作業的沿海船舶也加劇了航道的壅塞。
* **船長的信任與疲勞問題：** 船長對大副安全航行與避碰的能力充滿信心。然而，作為船上最忙碌的人，大副可能會低估自己在值班期間的身心疲勞，進而影響表現。
* **過度自信：** 對自身值班技能過度自信，可能導致大副忽視潛在風險或未採取必要的預防措施。
* **水手分心：** 值班的資深水手（AB）可能正忙於清潔駕駛台等工作，而非專注於瞭望職責，從而導致對周圍環境的目視監視出現盲區。
對大副的期望是能夠有效處理複雜情況，例如在狹窄水道中避免多船碰撞。傳統上，大副（C/O）負責訓練實習生與初階駕駛員（JO），使其保持對危險徵兆的警覺，並確保他們執行正確的程序來應對此類狀況。駕駛台資源管理（BHRM）的這一部分提供了雷達瞭望技巧，因為這些概念——雖然早在 1950 年代雷達繪圖的早期階段就已被注意到——依賴於基於本船與目標船「真速度向量」（True Speed Vector）的實用原則。這些原則受到自動避碰繪圖儀（ARPA）精度與雷達能力的影響。雖然自動識別系統（AIS）訊號可以提供目標船的真速度向量數據，但作為計算基礎的 GPS 位置，卻因地緣政治問題而進一步受到欺騙（故意偏置輸入）的威脅。這些也是我們在 BHRM 本部分所要探討並致力解決的挑戰。
5-01 進入交通繁忙區域
圖 5-01 紅色本船以航向 100⁰、對地航速 12.7 節接近長江口燈船
在圖 5-01 中，電子海圖（ECDIS）顯示本船位置（以紅線表示）正接近長江口燈船（L/V）。前方是一個以長江口燈船為中心的十字路口。航行值班駕駛員（OOW）應準備哪些符合良好船藝的常規情境意識措施？
**雷達 / ARPA / AIS 設定（如第 3 章所述）**
使用兩套或更多套設定不同的雷達。
* **X 頻段雷達設定（X-band Radar setting）：**
* 若要僅探測大型船舶，OOW 應降低雷達的「增益」（Gain）設定，以從螢幕上消除所有小型目標和海面雜波。
* 當 X 頻段雷達上不再顯示小型目標的回波時，螢幕上將僅保留大型船舶的回波。
* OOW 可以啟動 ARPA「自動捕獲」（Auto Acquisition）功能來自動捕獲大型船舶目標。（注意：與 S 頻段雷達相比，X 頻段 3 公分雷達顯示的回波較小；因此，只有大型船舶才能產生足夠強度的回波以顯示出來。）
* **S 頻段雷達設定（S-band Radar setting）：**
* 10 公分的 S 頻段雷達適用於探測近距離的小型目標，因為它的回波比 3 公分雷達上的回波大，且較少受到雨雪雜波的影響。
* 若要消除 10 公分雷達上的雨雪或海面雜波，OOW 可以降低增益設定。
* OOW 應將探測距離縮小至 3 浬，或將雷達偏心（off-center）設置以提供前方 5 浬的視野。較小的量程設定會放大螢幕上的回波尺寸。
* 當調整雷達以探測本船周圍的小型目標時，請將目標的速度向量（speed vector）和軌跡（trail）設定為「相對運動」（relative motion）。小型目標的相對運動線對觀察者來說更加直觀可見。
* 在相對運動模式下，本船可以透過將電子方位線（EBL）放置在目標的回波上，並根據軌跡的方向檢查方位變化，從而探測到小型目標的碰撞風險。
這兩種方法——使用相對運動速度向量 / 軌跡以及 EBL 設定——允許快速確認碰撞風險，從而在瞭望過程中節省寶貴的時間。
除了這兩套雷達的基本設定之外，大副還應採用其他瞭望方法，例如目視觀察或位於前桅的第三套雷達，以確保對所有目標進行全面評估。如果目標船舶較多，應利用真運動速度向量（後續討論）並結合適當的訓練來釐清整體狀況。
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Chapter 5: Knowledge Base for Chief Officer
A Chief Officer at sea is preparing for the role of Master, developing advanced maneuvering skills
and assuming greater responsibilities. As a key figure on board, the Chief Officer is expected to
oversee major safety aspects related to the ship's cargo and structure. In terms of navigational
safety, the Chief Officer serves as the Master’s backup whenever the Master is fatigued or otherwise
un able to perform their duties. The shipping company and the entire crew rely heavily on the Chief
Officer. Unfortunately, more than 50% of marine incidents occur during the Chief Officer's watch for
various reasons:
The 4-8 watch (both morning and evening) is particularly challenging for visual lookout, as
the twilight sun reflects at a near-horizontal angle, shining directly into the lookout's eyes and
making it difficult to spot potential hazards.
The hours just before sunrise are typically the sleepiest period of the day, which can reduce
alertness among those on watch.
Heavy traffic often occurs around harbor areas, with vessels eager to dock so that the 0800
day-shift workers can begin their tasks. Additionally, coastal vessels that have completed
afternoon cargo operations contribute to the congestion.
The Master has confidence in the Chief Officer's ability to navigate safely and avoid danger.
However, as the busiest person on board, the Chief Officer may underestimate their own
physical and mental fatigue during the watch, which can impact performance.
Overconfidence in their watchkeeping skills can lead the Chief Officer to overlook potential
risks or fail to take neces sary precautions.
Instead of focusing on lookout duties, the able-Bodied Seaman ( ab) on duty may be
occupied with tasks like cleaning the bridge, creating gaps in visual surveillance of the
surrounding area
For a Chief Officer, the expectation is to handle complex situations effectively, such as avoiding
multi-ship collisions in confined waterways. Traditionally, the Chief Officer (C/O) is responsible for
training cadets and Junior Officers (JOs) to keep them aware of danger signs and ensure they execute
proper procedures to cope with such situations. This part of Bridge Human Resource Management (
BHRM) provides radar lookout skills, as these concepts—although noted in the early stages of radar
plotting in the 1950s—rely on applic able principles based on the True Speed Vector of the ownship
and target vessels. These principles are influenced by the precision of Automatic Radar Plotting Aid (
ARPA) and radar cap abilities. While Automatic Identification System ( AIS) signals can provide True
Speed Vector data for target vessels, their GPS positions—which form the fundamental basis for
calculations—are further jeopardized by spoofing (deliberate biased input) due to geopolitical issues.
These are also the challenges we address and aim to resolve in this part of BHRM.
5- 01 Going into heavy traffic area
Fig 5 - 01 Red Ownship approaching Chang Jiang Mouth L/V with COG 100⁰ SOG 12.7 Knots
In Figure 5-01, the ECDIS display shows the ownship's position (indicated by the red line)
approaching the Chang Jiang Mouth Light Vessel (L/V). Ahead, a crossroads is centered on the Chang
Jiang Mouth light vessel. What should the Officer of the Watch ( OOW) prepare as routine situational
awareness measures in line with good seamanship?
Radar/ ARPA/ AIS Settings (as per Chapter 3)
Use two set radars or more in different setting.
X - band Radar setting:
To detect only large vessels, the OOW should reduce the radar's "gain" setting to eliminate
all small targets and sea clutter from the screen.
When small target echoes are no longer visible on the X-band radar, only echoes from large
vessels will remain on the screen.
The OOW can activate the ARPA "Auto Acquisition" function to automatically acquire targets
from large vessels. (Note that the X-band 3 cm radar displays smaller echoes compared to
the S-band radar; thus, only large vessels generate sufficient echo strength to appear.)
S - band Radar setting:
The 10 cm S-band radar is useful for detecting smaller targets at close range, as its echoes
are larger than those on the 3 cm radar and are less affected by snow or rain clutter.
To eliminate rain or sea clutter on the 10 cm radar, the OOW can lower the gain setting.
The OOW should reduce the detection range to 3 nautical miles or off-center the radar to
provide a 5-nautical-mile view ahead. A smaller range setting enlarges echo sizes on the
screen.
When adjusting the radar to detect small targets around the ownship, set the target speed
vector and trail to relative motion. Relative motion lines of small targets are more intuitively
visible to observers.
In relative motion mode, the ownship can detect collision risks from small targets by placing
the Electronic Bearing Line ( EBL) on the target's echo and checking for bearing variations
based on the trail's direction.
These two methods—using relative motion speed vectors/ trails and EBL settings—allow for
quick confirmation of collision risks, saving valu able time during lookout.
In addition to these basic settings with the two radars, the Chief Officer should also employ other
lookout methods, such as visual observation or a third radar located on the foremast, to ensure all
targets are thoroughly evaluated. If there are many target vessels, one should utilize the true motion
speed vector (discussed later) to clarify the overall situation, along with proper training.
COLREG Rule 20 and Extra lights on the deck
According to COLREG Rule 20, during the hours from sunset to sunrise:
Lighting Restrictions: No additional lights should be displayed, except those that cannot be
confused with the lights specified in the COLREGs. These lights must not diminish visibility
or distinctive character and should not interfere with maintaining a proper lookout.
Permissible Extra Lights: By adhering to these navigation light requirements, extra lights on
the deck are allowed, provided they meet the aforementioned criteria.
Master’s Discretion: The Master of the vessel should determine which deck or
accommodation lights can be used to enhance the ship's visual appearance.
Alleyway Lights: As proposed in the annex of the first chapter, alleyway lights
under deck containers or similar structures can be utilized to improve the visibility
of the vessel to others.
Comparative Visibility: It is quite remark able to note that a 50-seat bus typically
has at least four side lights on one side within a span of 12 meters. In contrast, a
vessel measuring 300 to 400 meters in length has only one sidelight per side, with
a maximum of four lights visible at any given time.
Detection Challenges: For one side of a 300-meter-long vessel, it has only three
lights to be visible. This makes detection difficult, especially in congested waters
filled with numerous fishing vessels (averaging 30 meters in length) and
background lights from the shoreline.
Reflection and Lookout Duties: These extra deck lights, intended to function as
auxiliary sidelights, should not create strong reflections or hinder lookout duties on
other vessels.
Pre- sailing Checks: The decision to utilize these auxiliary lights must be made,
and the arrangement should be verified by the Chief Officer or Master before the
vessel departs.
Activation of Lights: Once the vessel is at sea, the lookout merely needs to activate
these lights, which can be easily identified by red tape markings as deck extra
lights.
Instances like the sanchi and CF Crystal highlight the consequences of neglecting this precaution.
Extra deck lights can play a crucial role in helping other vessels distinguish large ships from the
multitude of fishing boats, especially in the waters of the Far East. It is strongly recommended that
vessels operating in high collision risk areas adopt this practice.
Figure 5 - 02 details of radar setting
Radar Settings and Competence
Radar settings are a reflection of your competence in conducting an effective radar lookout. It is
essential to utilize radar in search mode consistently. When examining the left-hand side of the radar
display, several key settings are visible:
Tuning:
Definition: Tuning involves adjusting the receiver frequency to align with the frequency of the
onboard transmitter oscillator. Automatic tuning is an accept able configuration. This
adjustment is neces sary because the frequencies generated in the X-band or S-band are
not fixed. The actual frequency range used is between 8.0 and 12.0 GHz, corresponding to a
wavelength range of 3.75 to 2.5 cm. Automatic tuning circuits adjust the receiver frequency
to each transmitted pulse, effectively "chasing" the frequencies just transmitted. Replicating
this process manually for each pulse is nearly impossible.
Gain:
Configuration: The gain is set to manual, which is also an accept able configuration. In
search mode, adjusting the receiver echo strength through the gain setting is crucial and
often the only effective means of accurately distinguishing small targets from clutter.
Vigilance Required: Since the gain is set to manual, the Officer of the Watch ( OOW) must
maintain high vigilance throughout their watch to prevent the loss of target echoes. Periodic
adjustments are essential to avoid misuse of the gain setting.
Regular Adjustments: The OOW should frequently adjust the gain setting to optimize the
identification of target echoes within the clutter detected by the ownship's radar. This practice
ensures that faint or small targets are not overlooked.
Impact on Clutter and Echoes: The gain setting directly impacts the amount of sea or rain
clutter displayed on the radar screen. A higher gain value increases the strength or number
of sea/rain clutter, which can diminish the strength of target echoes. If the gain and clutter
settings are not optimally adjusted during search mode, target echoes may not appear on the
screen, leading to potential oversight.
Indicator of Competence: Losing target traces on the radar is generally indicative of
incompetence in navigational watchkeeping. However, there are instances where target echo
strength is nearly indistinguish able from that of sea or rain clutter. Proper gain adjustment
alone may not suffice; in such cases, attempting to detect small targets using two different
radar sets, as previously mentioned, can be beneficial.
Influence of Reflection Angle
The strength of target echoes is significantly affected by the reflection angle of the radar waves.
When the radar is positioned on the bow of a vessel, it can achieve a more perpendicular reflection
angle from small targets. This perpendicular incidence results in stronger reflected radar waves
compared to those from rain or sea clutter, facilitating the differentiation of small target echoes amidst
surrounding clutter.
Influence of Wavelength
The S-band radar, with a wavelength of 10 cm, generally produces stronger echo signals, making
it more suit able for detecting small targets compared to X-band radar, which has a wavelength of 3
cm. The longer wavelength of the S-band radar allows it to interact more effectively with small objects,
generating more notice able echoes on the radar screen.
In summary, understanding and correctly adjusting radar settings is crucial for effective navigation
and collision avoidance. Maintaining competence in these practices is vital for ensuring safe maritime
operations.
Training the Officer of the Watch ( OOW) in manually adjusting the radar for search purposes is
primarily the responsibility of the Master. The Chief Officer should also be equipped to fulfill this
mentoring role. Whenever the Chief Officer or Master visits the bridge, they should verify that the radar
settings are correct for junior OOWs..
Sea/Rain Clutter Setting:
Manual Adjustment: A manual sea/rain clutter setting is accept able, but it requires careful
management.
Periodic Adjustments: The sea and rain clutter settings should be adjusted regularly to
ensure they are not set too high, as excessive settings can mask the echoes of small targets.
Verification Process: Each time the radar screen indicates no clutter, the OOW should
slightly reduce the sea/rain clutter setting to permit a small amount of clutter to reappear.
This adjustment helps confirm the accuracy of the setting.
As illustrated in the radar image of the sanchi (Figure 5-02), the manual sea clutter setting was set
at 40%, which was too high. This resulted in the echo of the large vessel CF Crystal di sappearing, and
the Third Officer failed to adjust the sea clutter setting even during the emergency.
Figure 5 - 03 detection range reflect traffic density
Adjusting Range Based on Target Density:
If there are numerous targets, reduce the display range to a smaller area. For instance, in Figure
5-03, the left side shows a range setting of 6 nautical miles (nm) with too many targets. In this case, the
radar range should be reduced to 3 nm (as shown on the right side). If 3 nm still displays an excessive
number of targets, further reduce it to a 1.5 nm detection range.
Analysis of Figure 5-03
On the left-hand side of Figure 5-03, the range setting of 6 nm displays an excessive number of
targets, making it challenging to determine which pose a danger. Typically, 6 nm is a common range for
junior Officers of the Watch ( OOWs) in open sea conditions.
However, if the Master observes a Third Officer (3/O) using a 3 nm range for radar lookout, they
should question the reasoning behind this choice. Several important considerations arise:
If there aren't many small targets, could the ownship be too close to the shore? Both
scenarios—an abundance of small targets or proximity to the shore—heighten the risk of
collision or grounding.
What about large targets that could potentially sink the ownship? Early warning is crucial for
these threats, which is only feasible with a long-range radar view.
Are the crew members competent enough to conduct an effective lookout and execute
collision-avoidance procedures within this limited 3 nm range for timely warnings?
While the 3/O might use the 3 nm range to positively identify small targets, this approach can
lead to overlooking large, fast-approaching vessels that quickly move beyond the 3 nm limit.
In a scenario with numerous small vessels, utilizing an additional radar set to detect ocean
going vessels would be advantageous.
This distinction is why senior and junior lookout procedures differ. The Chief Officer (C/O) will
alternate the detection range between 3 and 6 nm, while a 3/O may fixate on a single vessel,
as seen in the case of the 3/O on the sanchi, who focused solely on one target at a time.
Performance requirements for the Automatic Radar Plotting Aid ( ARPA) are often exceeded when
there are over 20 targets. It is unneces sary to track or collect data on every single target, as our short
term memory cannot manage such a large volume of information. Instead, categorize the workload into
two primary groups: large vessels on X-band radar and small fishing boats on S-band radar.
Job assignments for identifying small and large targets on the radar screen should be clearly
delineated. It is crucial not to rely blindly on past experiences in all situations. As noted in the previous
chapter, even a Master may struggle to fully master the skills required for effective radar lookout. This
seemingly minor oversight, stemming from improper radar lookout practices, can ultimately lead to a
collision incident.
Figure 5 - 04 Correct Trail setting in radar lookout
Radar Trails and Colision Avoidance
Where is the trail of the small vessel we are looking for?
In the left-hand image of Figure 5-04, the radar trails for targets were not correctly set, preventing
the Master from immediately assessing the collision risk. In contrast, Figure 2-19 displays radar echoes
with trails, facilitating better situational awareness.
Relative-Motion Trails: These trails can be quite long when there is high relative speed,
which may obscure the echoes of other targets.
True-Motion Trails: These are more advantageous when immediate information about target
movement is required.
When approaching a dense group of fishing boats, most of which are stationary, it is essential to
understand the behavior of these vessels. Fishermen, in order to avoid collisions with other boats in the
same school, typically have two options: they can either remain stationary or move in the same
direction and at the same speed as the other vessels.
In the first situation, a quick glance at the true-motion trail can significantly reduce the
perceived threat from stationary fishing vessels.
In the second situation, true-motion trails can easily help identify vessels with different
course and speed from other fishing vessels, which may indicate large ocean-going vessels.
In the 3-nm radar picture on the right, the radar trail was set to a 3-minute true motion, which is
shorter than the 6-minute true-motion setting for speed vectors.
The Master set the target trail to 3 minutes to indicate the past movement of the target,
allowing for an assessment of whether the target had changed course in the past three
minutes.
The Master utilized the acquired target true motion speed vectors (set to 6 minutes) to
determine the target's course and speed. However, for targets that had not been acquired, it
was challenging to accurately estimate their true course and speed using only the 3-minute
trail.
We recommend setting the trail length to match the time interval of the speed vectors, which in
this case should be 6 minutes. In this particular collision scenario, this seemingly minor difference in
settings was a contributing factor to the incident. The Master may have either overestimated the speed
of the two targets at the starboard bow or lacked reli able information about their speed without
displayed speed vectors, as these two targets had not been acquired.
A Chief Officer at sea is preparing for the role of Master, developing advanced maneuvering skills
and assuming greater responsibilities. As a key figure on board, the Chief Officer is expected to
oversee major safety aspects related to the ship's cargo and structure. In terms of navigational
safety, the Chief Officer serves as the Master’s backup whenever the Master is fatigued or otherwise
un able to perform their duties. The shipping company and the entire crew rely heavily on the Chief
Officer. Unfortunately, more than 50% of marine incidents occur during the Chief Officer's watch for
various reasons:
The 4-8 watch (both morning and evening) is particularly challenging for visual lookout, as
the twilight sun reflects at a near-horizontal angle, shining directly into the lookout's eyes and
making it difficult to spot potential hazards.
The hours just before sunrise are typically the sleepiest period of the day, which can reduce
alertness among those on watch.
Heavy traffic often occurs around harbor areas, with vessels eager to dock so that the 0800
day-shift workers can begin their tasks. Additionally, coastal vessels that have completed
afternoon cargo operations contribute to the congestion.
The Master has confidence in the Chief Officer's ability to navigate safely and avoid danger.
However, as the busiest person on board, the Chief Officer may underestimate their own
physical and mental fatigue during the watch, which can impact performance.
Overconfidence in their watchkeeping skills can lead the Chief Officer to overlook potential
risks or fail to take neces sary precautions.
Instead of focusing on lookout duties, the able-Bodied Seaman ( ab) on duty may be
occupied with tasks like cleaning the bridge, creating gaps in visual surveillance of the
surrounding area
For a Chief Officer, the expectation is to handle complex situations effectively, such as avoiding
multi-ship collisions in confined waterways. Traditionally, the Chief Officer (C/O) is responsible for
training cadets and Junior Officers (JOs) to keep them aware of danger signs and ensure they execute
proper procedures to cope with such situations. This part of Bridge Human Resource Management (
BHRM) provides radar lookout skills, as these concepts—although noted in the early stages of radar
plotting in the 1950s—rely on applic able principles based on the True Speed Vector of the ownship
and target vessels. These principles are influenced by the precision of Automatic Radar Plotting Aid (
ARPA) and radar cap abilities. While Automatic Identification System ( AIS) signals can provide True
Speed Vector data for target vessels, their GPS positions—which form the fundamental basis for
calculations—are further jeopardized by spoofing (deliberate biased input) due to geopolitical issues.
These are also the challenges we address and aim to resolve in this part of BHRM.
5- 01 Going into heavy traffic area
Fig 5 - 01 Red Ownship approaching Chang Jiang Mouth L/V with COG 100⁰ SOG 12.7 Knots
In Figure 5-01, the ECDIS display shows the ownship's position (indicated by the red line)
approaching the Chang Jiang Mouth Light Vessel (L/V). Ahead, a crossroads is centered on the Chang
Jiang Mouth light vessel. What should the Officer of the Watch ( OOW) prepare as routine situational
awareness measures in line with good seamanship?
Radar/ ARPA/ AIS Settings (as per Chapter 3)
Use two set radars or more in different setting.
X - band Radar setting:
To detect only large vessels, the OOW should reduce the radar's "gain" setting to eliminate
all small targets and sea clutter from the screen.
When small target echoes are no longer visible on the X-band radar, only echoes from large
vessels will remain on the screen.
The OOW can activate the ARPA "Auto Acquisition" function to automatically acquire targets
from large vessels. (Note that the X-band 3 cm radar displays smaller echoes compared to
the S-band radar; thus, only large vessels generate sufficient echo strength to appear.)
S - band Radar setting:
The 10 cm S-band radar is useful for detecting smaller targets at close range, as its echoes
are larger than those on the 3 cm radar and are less affected by snow or rain clutter.
To eliminate rain or sea clutter on the 10 cm radar, the OOW can lower the gain setting.
The OOW should reduce the detection range to 3 nautical miles or off-center the radar to
provide a 5-nautical-mile view ahead. A smaller range setting enlarges echo sizes on the
screen.
When adjusting the radar to detect small targets around the ownship, set the target speed
vector and trail to relative motion. Relative motion lines of small targets are more intuitively
visible to observers.
In relative motion mode, the ownship can detect collision risks from small targets by placing
the Electronic Bearing Line ( EBL) on the target's echo and checking for bearing variations
based on the trail's direction.
These two methods—using relative motion speed vectors/ trails and EBL settings—allow for
quick confirmation of collision risks, saving valu able time during lookout.
In addition to these basic settings with the two radars, the Chief Officer should also employ other
lookout methods, such as visual observation or a third radar located on the foremast, to ensure all
targets are thoroughly evaluated. If there are many target vessels, one should utilize the true motion
speed vector (discussed later) to clarify the overall situation, along with proper training.
COLREG Rule 20 and Extra lights on the deck
According to COLREG Rule 20, during the hours from sunset to sunrise:
Lighting Restrictions: No additional lights should be displayed, except those that cannot be
confused with the lights specified in the COLREGs. These lights must not diminish visibility
or distinctive character and should not interfere with maintaining a proper lookout.
Permissible Extra Lights: By adhering to these navigation light requirements, extra lights on
the deck are allowed, provided they meet the aforementioned criteria.
Master’s Discretion: The Master of the vessel should determine which deck or
accommodation lights can be used to enhance the ship's visual appearance.
Alleyway Lights: As proposed in the annex of the first chapter, alleyway lights
under deck containers or similar structures can be utilized to improve the visibility
of the vessel to others.
Comparative Visibility: It is quite remark able to note that a 50-seat bus typically
has at least four side lights on one side within a span of 12 meters. In contrast, a
vessel measuring 300 to 400 meters in length has only one sidelight per side, with
a maximum of four lights visible at any given time.
Detection Challenges: For one side of a 300-meter-long vessel, it has only three
lights to be visible. This makes detection difficult, especially in congested waters
filled with numerous fishing vessels (averaging 30 meters in length) and
background lights from the shoreline.
Reflection and Lookout Duties: These extra deck lights, intended to function as
auxiliary sidelights, should not create strong reflections or hinder lookout duties on
other vessels.
Pre- sailing Checks: The decision to utilize these auxiliary lights must be made,
and the arrangement should be verified by the Chief Officer or Master before the
vessel departs.
Activation of Lights: Once the vessel is at sea, the lookout merely needs to activate
these lights, which can be easily identified by red tape markings as deck extra
lights.
Instances like the sanchi and CF Crystal highlight the consequences of neglecting this precaution.
Extra deck lights can play a crucial role in helping other vessels distinguish large ships from the
multitude of fishing boats, especially in the waters of the Far East. It is strongly recommended that
vessels operating in high collision risk areas adopt this practice.
Figure 5 - 02 details of radar setting
Radar Settings and Competence
Radar settings are a reflection of your competence in conducting an effective radar lookout. It is
essential to utilize radar in search mode consistently. When examining the left-hand side of the radar
display, several key settings are visible:
Tuning:
Definition: Tuning involves adjusting the receiver frequency to align with the frequency of the
onboard transmitter oscillator. Automatic tuning is an accept able configuration. This
adjustment is neces sary because the frequencies generated in the X-band or S-band are
not fixed. The actual frequency range used is between 8.0 and 12.0 GHz, corresponding to a
wavelength range of 3.75 to 2.5 cm. Automatic tuning circuits adjust the receiver frequency
to each transmitted pulse, effectively "chasing" the frequencies just transmitted. Replicating
this process manually for each pulse is nearly impossible.
Gain:
Configuration: The gain is set to manual, which is also an accept able configuration. In
search mode, adjusting the receiver echo strength through the gain setting is crucial and
often the only effective means of accurately distinguishing small targets from clutter.
Vigilance Required: Since the gain is set to manual, the Officer of the Watch ( OOW) must
maintain high vigilance throughout their watch to prevent the loss of target echoes. Periodic
adjustments are essential to avoid misuse of the gain setting.
Regular Adjustments: The OOW should frequently adjust the gain setting to optimize the
identification of target echoes within the clutter detected by the ownship's radar. This practice
ensures that faint or small targets are not overlooked.
Impact on Clutter and Echoes: The gain setting directly impacts the amount of sea or rain
clutter displayed on the radar screen. A higher gain value increases the strength or number
of sea/rain clutter, which can diminish the strength of target echoes. If the gain and clutter
settings are not optimally adjusted during search mode, target echoes may not appear on the
screen, leading to potential oversight.
Indicator of Competence: Losing target traces on the radar is generally indicative of
incompetence in navigational watchkeeping. However, there are instances where target echo
strength is nearly indistinguish able from that of sea or rain clutter. Proper gain adjustment
alone may not suffice; in such cases, attempting to detect small targets using two different
radar sets, as previously mentioned, can be beneficial.
Influence of Reflection Angle
The strength of target echoes is significantly affected by the reflection angle of the radar waves.
When the radar is positioned on the bow of a vessel, it can achieve a more perpendicular reflection
angle from small targets. This perpendicular incidence results in stronger reflected radar waves
compared to those from rain or sea clutter, facilitating the differentiation of small target echoes amidst
surrounding clutter.
Influence of Wavelength
The S-band radar, with a wavelength of 10 cm, generally produces stronger echo signals, making
it more suit able for detecting small targets compared to X-band radar, which has a wavelength of 3
cm. The longer wavelength of the S-band radar allows it to interact more effectively with small objects,
generating more notice able echoes on the radar screen.
In summary, understanding and correctly adjusting radar settings is crucial for effective navigation
and collision avoidance. Maintaining competence in these practices is vital for ensuring safe maritime
operations.
Training the Officer of the Watch ( OOW) in manually adjusting the radar for search purposes is
primarily the responsibility of the Master. The Chief Officer should also be equipped to fulfill this
mentoring role. Whenever the Chief Officer or Master visits the bridge, they should verify that the radar
settings are correct for junior OOWs..
Sea/Rain Clutter Setting:
Manual Adjustment: A manual sea/rain clutter setting is accept able, but it requires careful
management.
Periodic Adjustments: The sea and rain clutter settings should be adjusted regularly to
ensure they are not set too high, as excessive settings can mask the echoes of small targets.
Verification Process: Each time the radar screen indicates no clutter, the OOW should
slightly reduce the sea/rain clutter setting to permit a small amount of clutter to reappear.
This adjustment helps confirm the accuracy of the setting.
As illustrated in the radar image of the sanchi (Figure 5-02), the manual sea clutter setting was set
at 40%, which was too high. This resulted in the echo of the large vessel CF Crystal di sappearing, and
the Third Officer failed to adjust the sea clutter setting even during the emergency.
Figure 5 - 03 detection range reflect traffic density
Adjusting Range Based on Target Density:
If there are numerous targets, reduce the display range to a smaller area. For instance, in Figure
5-03, the left side shows a range setting of 6 nautical miles (nm) with too many targets. In this case, the
radar range should be reduced to 3 nm (as shown on the right side). If 3 nm still displays an excessive
number of targets, further reduce it to a 1.5 nm detection range.
Analysis of Figure 5-03
On the left-hand side of Figure 5-03, the range setting of 6 nm displays an excessive number of
targets, making it challenging to determine which pose a danger. Typically, 6 nm is a common range for
junior Officers of the Watch ( OOWs) in open sea conditions.
However, if the Master observes a Third Officer (3/O) using a 3 nm range for radar lookout, they
should question the reasoning behind this choice. Several important considerations arise:
If there aren't many small targets, could the ownship be too close to the shore? Both
scenarios—an abundance of small targets or proximity to the shore—heighten the risk of
collision or grounding.
What about large targets that could potentially sink the ownship? Early warning is crucial for
these threats, which is only feasible with a long-range radar view.
Are the crew members competent enough to conduct an effective lookout and execute
collision-avoidance procedures within this limited 3 nm range for timely warnings?
While the 3/O might use the 3 nm range to positively identify small targets, this approach can
lead to overlooking large, fast-approaching vessels that quickly move beyond the 3 nm limit.
In a scenario with numerous small vessels, utilizing an additional radar set to detect ocean
going vessels would be advantageous.
This distinction is why senior and junior lookout procedures differ. The Chief Officer (C/O) will
alternate the detection range between 3 and 6 nm, while a 3/O may fixate on a single vessel,
as seen in the case of the 3/O on the sanchi, who focused solely on one target at a time.
Performance requirements for the Automatic Radar Plotting Aid ( ARPA) are often exceeded when
there are over 20 targets. It is unneces sary to track or collect data on every single target, as our short
term memory cannot manage such a large volume of information. Instead, categorize the workload into
two primary groups: large vessels on X-band radar and small fishing boats on S-band radar.
Job assignments for identifying small and large targets on the radar screen should be clearly
delineated. It is crucial not to rely blindly on past experiences in all situations. As noted in the previous
chapter, even a Master may struggle to fully master the skills required for effective radar lookout. This
seemingly minor oversight, stemming from improper radar lookout practices, can ultimately lead to a
collision incident.
Figure 5 - 04 Correct Trail setting in radar lookout
Radar Trails and Colision Avoidance
Where is the trail of the small vessel we are looking for?
In the left-hand image of Figure 5-04, the radar trails for targets were not correctly set, preventing
the Master from immediately assessing the collision risk. In contrast, Figure 2-19 displays radar echoes
with trails, facilitating better situational awareness.
Relative-Motion Trails: These trails can be quite long when there is high relative speed,
which may obscure the echoes of other targets.
True-Motion Trails: These are more advantageous when immediate information about target
movement is required.
When approaching a dense group of fishing boats, most of which are stationary, it is essential to
understand the behavior of these vessels. Fishermen, in order to avoid collisions with other boats in the
same school, typically have two options: they can either remain stationary or move in the same
direction and at the same speed as the other vessels.
In the first situation, a quick glance at the true-motion trail can significantly reduce the
perceived threat from stationary fishing vessels.
In the second situation, true-motion trails can easily help identify vessels with different
course and speed from other fishing vessels, which may indicate large ocean-going vessels.
In the 3-nm radar picture on the right, the radar trail was set to a 3-minute true motion, which is
shorter than the 6-minute true-motion setting for speed vectors.
The Master set the target trail to 3 minutes to indicate the past movement of the target,
allowing for an assessment of whether the target had changed course in the past three
minutes.
The Master utilized the acquired target true motion speed vectors (set to 6 minutes) to
determine the target's course and speed. However, for targets that had not been acquired, it
was challenging to accurately estimate their true course and speed using only the 3-minute
trail.
We recommend setting the trail length to match the time interval of the speed vectors, which in
this case should be 6 minutes. In this particular collision scenario, this seemingly minor difference in
settings was a contributing factor to the incident. The Master may have either overestimated the speed
of the two targets at the starboard bow or lacked reli able information about their speed without
displayed speed vectors, as these two targets had not been acquired.
