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相关连结:https://mp.weixin.qq.com/s/iKGQ-28JyxSuomw41m8Idw
https://mp.weixin.qq.com/s/iKGQ-28JyxSuomw41m8Idw
Milano Bridge 事故检讨,该轮领港用右舵20度转向,造成回转速率不够。并且对满舵回转没有能力,也没有信心操控,原因有三,知识不够,训练不足,做得太少。 以上说明,请看近接避碰第四章。
RUDDER CYCLING循环舵,或是左右满舵操传法,不知各位有没有印象?
现在我们来介绍一下,左右满舵停船法又称 Z 型减速法。
IMO 的 Z 字形试验是做两次,一次用舵角 10 度转船艏向两舷各 10 度,一次 是用舵角 20 度转船艏向两舷各 20 度。上图所示,起始是使用右舵 10 度,
当船艏向改变到右边 10 度时,便使用反向左舵 10 度。当船艏向来到左边 10 度以后,立即转到右舵 10 度,以回到原航向。这是在测试船只的操舵性能, 跟回转过度的趋势。
Z 字型减速法 = 左右满舵停船法
图 4-07 IMO 的 10 度 Z 字形回转试验
Z 字型减速的操船测试
当新船长上一条新船工作时,建议应该是做 Z 字型减速的操船测试,这是操 船的知识,我们需要收集,船舶 Z 字型减速回转特性的资料,当使用的时机 来临时,船长将会得到许多的帮助。用於避免碰撞搁浅,都是使用这些减速 资料的时机。
每当有机会,提前半小时抵达引水站,且周围没有其他船只来往困扰的时候, 船长应当找个适当的海面,把速度降低到在港的全速 Harbor Full Ahead,并 稳定在新航线上,以便测试。所有的位置应被精确的定位,使用 GPS 可以得 到很好的帮助,因为在新的机型上,只要按一个单独的按钮,便会有记忆过 去船位的功能。DGPS 的位置误差,更可以在 15 米之内。前面说的是十年前 的事,现在只要回放电子海图资料处理系统的显示器 ECDIS (playback),一切 的资料都一清二楚,现在其实已经进入,人人可以做领港的时代,好像有了 飞行模拟电玩,人人都可以开飞机的时代。
使用舵角的大小与能否控制回转速率是不相干的
近接避碰56 李文愚
当航向与航速都稳定了以后,船长就可以开始测试,现在应当停车,用满舵 使船舶回转。用满舵听起来是荒唐的,有经验的船长,可能牢记于心的是, 船舶在回转的时候,在某些阶段,回转速率太高的话,回转可能会失去控制。 例如用某个舵令(如 5 度右舵)来启动船舶回转的时候,如果回正舵(Midship) 以后,回转率没有降低,就需要将近双倍的舵角(如左舵 10 度),去阻止回转。 即使我们立即
用双倍的反舵,来稳住船艏向,船首向有时仍会,超出先前设定的 艏向一些角度(Overshoot)。控制船艏向的重点是,船只的回转速 率,要始终
都在船长的监督之下,并不是船长用多大的舵角去启动回转。这是我们操船
的技术盲点之ㄧ。
图 4-08 进距 使用的舵角大小与船只的回转速率,与操船者的技术息息相关的。回转速率
是由每分钟转 5 度,每分钟转 10 度,每分钟转 15 度,慢慢增加的。舵角越 大则回转速率增加越快。即使用的舵角小,只要时间够久,或者是外面风向 水流的相互影响,船只的回转速率,也有可能到达失控的地步。使用舵角的 大小与能否控制回转速率是不相干的,这是操船者必须具备的技术能力之 ㄧ,也是我们需要培养的能力之ㄧ。
图 4-09 Z 字型减速的操船
Z 字型减速不是普通的操船转向,目的是能尽快,使船舶的速度减下来。用满 舵的舵板去挡水减速,当然效果有限,但是因为船体回转,利用船身侧面积 与船只的前进方向的不同,产生的阻力来煞俥减速,却是个不错的方法。回 转动力产生的漂流角,使整个船体侧面在水中的动作,像一个巨大的舵板在 挡水。如上图 4-7 船身的方向是红线,船只的前进方向是蓝线,当然两者的 夹角越大,减速效果越好,前提是船只不可失去控制,也就是回转速率,始 终都在我们可以控制的范围。
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