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相關連結:https://mp.weixin.qq.com/s/iKGQ-28JyxSuomw41m8Idw
https://mp.weixin.qq.com/s/iKGQ-28JyxSuomw41m8Idw
Milano Bridge 事故檢討,該輪領港用右舵20度轉向,造成迴轉速率不夠。並且對滿舵迴轉沒有能力,也沒有信心操控,原因有三,知識不夠,訓練不足,做得太少。 以上說明,請看近接避碰第四章。
RUDDER CYCLING循環舵,或是左右滿舵操傳法,不知各位有沒有印象?
現在我們來介紹一下,左右滿舵停船法又稱 Z 型減速法。
IMO 的 Z 字形試驗是做兩次,一次用舵角 10 度轉船艏向兩舷各 10 度,一次 是用舵角 20 度轉船艏向兩舷各 20 度。上圖所示,起始是使用右舵 10 度,
當船艏向改變到右邊 10 度時,便使用反向左舵 10 度。當船艏向來到左邊 10 度以後,立即轉到右舵 10 度,以回到原航向。這是在測試船隻的操舵性能, 跟迴轉過度的趨勢。
Z 字型減速法 = 左右滿舵停船法
圖 4-07 IMO 的 10 度 Z 字形迴轉試驗
Z 字型減速的操船測試
當新船長上一條新船工作時,建議應該是做 Z 字型減速的操船測試,這是操 船的知識,我們需要收集,船舶 Z 字型減速迴轉特性的資料,當使用的時機 來臨時,船長將會得到許多的幫助。用於避免碰撞擱淺,都是使用這些減速 資料的時機。
每當有機會,提前半小時抵達引水站,且周圍沒有其他船隻來往困擾的時候, 船長應當找個適當的海面,把速度降低到在港的全速 Harbor Full Ahead,並 穩定在新航線上,以便測試。所有的位置應被精確的定位,使用 GPS 可以得 到很好的幫助,因為在新的機型上,只要按一個單獨的按鈕,便會有記憶過 去船位的功能。DGPS 的位置誤差,更可以在 15 米之內。前面說的是十年前 的事,現在只要回放電子海圖資料處理系統的顯示器 ECDIS (playback),一切 的資料都一清二楚,現在其實已經進入,人人可以做領港的時代,好像有了 飛行模擬電玩,人人都可以開飛機的時代。
使用舵角的大小與能否控制迴轉速率是不相干的
近接避碰56 李文愚
當航向與航速都穩定了以後,船長就可以開始測試,現在應當停車,用滿舵 使船舶迴轉。用滿舵聽起來是荒唐的,有經驗的船長,可能牢記于心的是, 船舶在迴轉的時候,在某些階段,迴轉速率太高的話,迴轉可能會失去控制。 例如用某個舵令(如 5 度右舵)來啟動船舶迴轉的時候,如果回正舵(Midship) 以後,迴轉率沒有降低,就需要將近雙倍的舵角(如左舵 10 度),去阻止迴轉。 即使我們立即
用雙倍的反舵,來穩住船艏向,船首向有時仍會,超出先前設定的 艏向一些角度(Overshoot)。控制船艏向的重點是,船隻的迴轉速 率,要始終
都在船長的監督之下,並不是船長用多大的舵角去啟動迴轉。這是我們操船
的技術盲點之ㄧ。
圖 4-08 進距 使用的舵角大小與船隻的迴轉速率,與操船者的技術息息相關的。迴轉速率
是由每分鐘轉 5 度,每分鐘轉 10 度,每分鐘轉 15 度,慢慢增加的。舵角越 大則迴轉速率增加越快。即使用的舵角小,只要時間夠久,或者是外面風向 水流的相互影響,船隻的迴轉速率,也有可能到達失控的地步。使用舵角的 大小與能否控制迴轉速率是不相干的,這是操船者必須具備的技術能力之 ㄧ,也是我們需要培養的能力之ㄧ。
圖 4-09 Z 字型減速的操船
Z 字型減速不是普通的操船轉向,目的是能盡快,使船舶的速度減下來。用滿 舵的舵板去擋水減速,當然效果有限,但是因為船體迴轉,利用船身側面積 與船隻的前進方向的不同,產生的阻力來煞俥減速,卻是個不錯的方法。迴 轉動力產生的漂流角,使整個船體側面在水中的動作,像一個巨大的舵板在 擋水。如上圖 4-7 船身的方向是紅線,船隻的前進方向是藍線,當然兩者的 夾角越大,減速效果越好,前提是船隻不可失去控制,也就是迴轉速率,始 終都在我們可以控制的範圍。
Contact with Gantries and moored vessel while approaching berth
We would like to draw your attention to the following catastrophic Allision accident that involved our operated vessel.
<Summary> ONE operated 13900 TEU vessel contacted with multiple shore gantries and with one moored container vessel while approaching berth at PNC #8, Pusan New Port on the 6th Apr’20. This was her first berthing for phasing-in after Dry Dock.
<Time line (LT)> [ Two Tugs in action throughput below timeline, FWD and AFT, could not provide
adequate pull due to the high FWD speed, use of Bow thruster not fully known]
14:37: Commenced STBD turn, STBD 20 Helm, Dead Slow Ahead, Speed: 9.3Kts
14:39: Stopped engine, Speed: 7.6 Kts
14:40: Pilot appeared panicked, Speed 7.6 Kts, Dead slow ahead STBD 20 helm.
14:42: Pilot realizes heavy drift to port, panicked, full ahead engine, hard Stbd helm, concerned to avoid three (3) moored vessels. AFT Tug continuously pulling.
14:44: Cleared 1st moored vessel, drifting towards 2nd moored vessel, Navigation full ahead, STBD 20 helm, drifting further towards berth. FWD tug’s action not known as pilot speaking in local language. Master used BT.
14:47: Cleared 2nd moored vessel, random orders on ME and rudder, stern drifting towards port side, Speed 6 kts. 14:47: Cleared lesser beamed 3rd moored vessel.
14:49: Made hard contact with Gantry no.85 , fully collapsed on stern of ONE vessel. ME Nav full ahead, speed. 5.2 kts. FWD tug not pulling.
14:50: Emergency full stern to prevent contact with moored vessel ahead.
14:52: Hard contact with Gantry crane no. 81 by bridge wing, which was working on the moored container vessel ahead followed by slight contact with the moored vessel around Bay 02 & 06.
Ocean Network Express Pte. Ltd. 7 Straits View, Marina One East Tower #16-01/03 and #17-01/06
[1]
Ocean Network Express Pte. Ltd. 7 Straits View, Marina One East Tower #16-01/03 and #17-01/06
Singapore 018936
<Known Damages So Far> Gantries & Berth
• One gantry fully collapsed on the ONE vessel’s stern area and parts dropped into water, crane total loss.
• Another gantry badly damaged, inclined out of shape almost about to fall, inopeartional.
• Another two gantries externally damaged and derailed, inoperational
• Next two gantries externally damamged, among whch one is operational.
• Total 6 Gantries damaged among which 5 inoperational (incl. 1 total loss) & 1 operational prsently
• Damages to berth: Unknown at this time
• 580 Meters length of total 2000Mtrs of PNC out of commision at this time. Damages to the Ship
• Heavy hull breach above water line around port quarter under deck passage.
• AFT lashing bridges severely damaged
• Deck plating & fittings distorted at several locations of port side
• Propellar damaged
• Port side bridge wing damaged
• Above all damges are extended in various locations hence further examination in progress. Injury & Pullution
One (1) shore staff slightly injured(by local news), no pollution.
Damages to the contacted moored container vessel
Pending investigation & survey
Actions taken so far
Debris of the collapsed gantry carne removed from seabed and from ONE vessel. Traffic in the harbour area normal.
<What went wrong>
1. High approach speed.
• Uncontrollable speed.
• Very less reaction time after the turn.
• Lessened effect of tug’s pull due to high FWD speed
• No effect of Bow Thruster
2. Failure to recognise vessel’s condition
• Light condition, partly submerged Rudder and propeller providing less steering effect & lesser
ROT. Propeller immersion: approx. 60%, Rudder Immersion: Partial corresponding to propeller
immersion
• Light condition provides large exposed transom and less parallel body & quick response to helm
and engine, hence very careful approach to berth is required.
3. Failure to recognise local conditions
• Light condition of vessel is affected by wind easily even with gusts of 10~15Kts.
• Land breeze effect resulting on-shore wind is expected during berthing at around noon time.
• Flood tide contributed the lesser effect of the Rudder and more speed.
4. From the beginning of the turn to a substantial period 20 Degrees of STBD helm used, resulted in less ROT, a quicker turn could have given the vessel better clearance from the moored vessels and the berth.
5. Failure to challenge Pilot’s intention of
• High approach speed was not challenged by Bridge team even when the pilot’s panic was noticed
well in advance.
• Not choosing the other approach from south of the Island to have better control on a flood tide.
[2]
<We Request>
Ocean Network Express Pte. Ltd. 7 Straits View, Marina One East Tower #16-01/03 and #17-01/06
Singapore 018936
1. Please establish good BTM and BRM with attention to controllable speed during all approaches.
2. Prepare speed down plan for every approach and challenge Pilot if he deviates from that.
3. Recognize current condition of your vessel, her maneuverability in present local conditions before
every maneuver and explain adequately to the pilot. Monitor pilot’s each action, verify if in doubt,
take necessary action without hesitation, if not satisfied.
4. Please review MSQ 135/2019, MSQ Accident News Digest (Collision, Allision & Grounding) and carry
out training of all bridge team members.
** The Accident news shared by this letter is still under investigation, based on currently available information from various sources & will be updated with new findings, should need be.
We appreciate your attention to safety always, let’s strive towards ZERO accidents.
Capt.Nobuyuki YAMAOKA Senior Vice President Marine Safety & Quality