Friday, April 30, 2021

KRI Nanggala 402 Submarine - The first submarine tragedy in Southeast Asia

On 25 April (Sunday), photos taken from the Deep Search and Rescue Six (DSAR6) submersible vessel reveal that KRI Nanggala 402 submarine is broken into at least 3 pieces lying on the 850m seabed. The DSAR6 is carried onboard MV Swift Rescue, a submarine rescue vessel deployed by the Republic of Singapore Navy.

Military personnel are trained for warfare. They may loss their lives when defending the sovereignty of a nation in time of war or conflict. Such tragic incident during peacetime is an occupation hazard which submariners are subjected to as a team.  

My heart goes along with the families of our Indonesia neighbour.


KRI Nanggala 402 submarine during exercise in 1992. Photo: Wikipedia

 

Sequence of events

Sub miss: On 21 April (Wednesday) the KRI Nanggala 402 submarine asked for permission to dive at 3am Indonesia time. At 4.30am the submarine went missing with 53 people on board when taking part in a torpedo drill in north Bali waters. Those people include 49 crew members, one ship commander and three weapon specialists.

Sub sank: On 24 April (Saturday) the Indonesia military chief Hadi Tjahjanto was speaking at a press conference, saying that the navy had found oil spill and recovered debris and items which are evidence that the KRI Nanggala had sunk. These items would not have come outside the submarine if there was no external pressure or without damage to its torpedo launcher. Those objects include part of a torpedo, part of a praying mat, grease and a submarine part that was manufactured in South Korea.  The KRI Nanggala 402 was retrofitted in South Korea in 2012.

No miracle: On 25 April (Sunday), closed range photos shot by DSAR6 confirmed the mishap.

The submarine is a German Type 209 variant, built to withstand up to 500m depth. The pressure hull will collapse beyond 500m. The way a pressure vessel collapse is usually crushed like an empty Coca Cola can, torn apart and may break into several pieces. Indeed, the disintegrated hull sections and fittings of KRI Nanggala 402 were captured by underwater cameras. 

An image from the camera of the MV Swift Rescue vessel, captured at a depth of 838m, showing hull parts from the sunken submarine. Photo: The Indonesian Navy


The recent submarine incidents

The speculation for KRI Nanggala 402 submarine tragedy is probably due to power failure. Torpedo explosion has been ruled out because in the event of such detonation, the hull would be fragmented into many smaller pieces. 

While the oxygen tanks may enable the crew to survive up to Saturday, such collapse implies that the crew may have lost their lives at the instance when the submarine dove beyond its depth limit. It is within seconds.

On 27 April (Tuesday), Two Indonesia senior naval officers suggested that another possible cause is strong underwater wave forcing the submarine to descend at an uncontrollable manner. At the spot where the submarine was missing, the movement of a strong internal wave is captured by the satellite image report of Japanese weather satellite Himawari 8 as well as European one. Such underwater wave was created due to seawater density difference between the Lombok Strait and the much deeper waters north of Bali where the KRI Nanggala 402 was.   

Such tragedy reminded me several other submarine incidents happened during my former career.

In August 2000, Russian Oscar II class submarine (the world's largest cruise-missile submarine), Kursk sank in the Barents Sea. A leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead which in turn triggered the explosion of around half a dozen other warheads about two minutes later. Investigation revealed that 118 sailors died on the spot. 23 survived from initial explosion and subsequently perished from cold and Carbon Dioxide build up in another watertight compartment.

On 8 Jan 2005, the Los Angeles class submarine, USS San Francisco collided head-on with an undersea mountain 350 miles south of Guam. The submarine experienced a rapid deceleration from about 35 knots to 0 in 4 seconds. One sailor died and around 60 sailors injured in the accident. The submarine sustained severe damages and had been decommissioned.


Source: John D. Shaw presented to the 24th International System Safety Conference 3 August 2006

 

Loads on a submarine pressure hull

During my postgraduate study and subsequent exposure, I learned about design of submarine and the BS5500 pressure vessel code in greater depth. BS5500 is now PD 5500 “Specification for unfired, fusion welded pressure vessels”.

Comparing surface ship with submarine, surface ship operates in a 2D environment i.e. on sea surface. Submarine operates in a 3D environment with an additional dimension of depth when submerging underwater.

Modern submarine has a pressure hull joined with a dome and a cylindrical body to withstand water pressure (hydrostatic pressure). Structurally, round form has the best all rounded strength to withstand various stresses with the least materials. 

The plate thickness of a pressure hull would range from about 18mm for a WW2 German’s U-boat to 76mm for a nuclear submarine. For comparison, the weight of the 59m KRI Nanggala 402 is about 1400 ton. A surface warship of similar length but armed with many more warfare equipment and machinery would be around 500+ ton. It shows how massive a submarine pressure hull contribute to the overall weight.

KRI Nanggala 402 specifications. Source: BBC

Submarine also has an external light hull (casing). The casing is a non-watertight hull which provides hydrodynamically efficient shape. It allows for free flooding in order to achieve pressure equilibrium.

During operations, the loads acted on a submarine’s pressure hull can be classified as follows:

1.  Loading due to external underwater pressure

Based on physics, every 10m underwater is equivalent to an additional load of about 1 atmospheric pressure (1 bar). 1 atmospheric pressure is the air pressure we live on land. Hence, at 10m depth, we are subjected to double the normal air pressure.

For the case of KRI Nanggala 402, it means the structural integrity will be completely lost when subjected to 50 times atmospheric pressure (50 bar) at 500m depth.

Indeed, depth is one of the most important and deciding structural design criteria. The pressure hull must be able to withstand such high differential pressure while maintaining normal air pressure within those internal watertight spaces.

There are maximum operating depth (service depth), emergency depth (dive deeper than the service depth under emergency conditions such as escape from enemy) and collapse depth (crush depth). Collapse depth is what KRI Nanggala 402 had encountered.

2. Shock Loads

Submarine is designed for war to withstand loads generated by underwater mine explosion. Such explosion would generate large underwater gas bubbles. When such bubbles burst, they release huge energy (shock load) which may cause severe structural damages. The common engineering term for this is called “shock factor”.

Apart from direct shock load, each shock wave (travel at about 1500 m/s, 5 times the speed of sound in air) from a single underwater explosion generates a wave of vibration propagate along the submarine hull. Vibratory loads reduce fatigue life and can cause resonance resulting in major structural failure.

Navy ship subjected to an underwater shock test. Photo source: Wikipedia. By Camera Operator: PH1 Toon, USN - ID:DN-SC-87-05360 / Service Depicted: Navy, Public Domain

3. Other dynamic loads

A submarine, when surfaced, is just like any other surface ships, subjected to longitudinal bending, transverse shear and torsional stresses due to wave action. Other localised loads come from heavy machinery such as generator engines, and weapons such as torpedoes and missiles, among others.

 

Quality control

The pressure hull is generally constructed using thick high-strength alloyed steel with complex stiffening reinforcement. The pressure hull is usually separated with watertight bulkheads into several compartments to enhance survivability.

Quality control during construction and maintenance for submarine has to be very stringent and require high degree of discipline and precision. Not many shipyards in the world are able to undertake such skillful tasks.

For example, any small notch on the pressure hull is equivalent to a stress riser that weakens the load bearing capacity, hence out of roundness standard is a vital component in the pressure vessel code. Welding of thick materials tend to create hazardous heat affected zone (HAZ) which reduces material strength. Hull penetration for piping and electrical cables would compromise watertight integrity. These are just part of the many work control processes for those who worked on submarine safety program.

For many, these tight measures are implemented to save assets. To me, these measures are to save lives.

Friday, April 23, 2021

你打针了吗? ---- 冠状病毒疫苗接种

从前街坊碰面,最常用的问候语是“吃饱没”,如今则是“打针没”。

2021年331日和421日,相隔21天,我共打了两剂辉瑞(Pfizer-BioNTech COVID-19)疫苗,这是美国制药公司辉瑞(Pfizer)和德国医药公司BioNTech联合研制成的产品。由于有效期估计为9个月(厂家的看法)至18个月(新加坡的看法),因此可能在疫情未完全控制下来的期间,必须打第三针。

我选择设在Tampines Hub旁临时搭建的疫苗接种中心,由Fullerton Health Group负责。现场有许多年轻人,使用华语和英语跟到场打针的人士沟通。这些年轻人可能是毕业后找不到正职,刚好有份临时差事可做。

现场的流程相当顺畅,先根据预约与到场时间顺序就坐,核对身份后就可以走入冷气帐篷打针了。我是通过Singpass的电子居民证核实的。打针后到休息站坐下来观察半个小时,点名领取打针证明书后就可以离开。事有凑巧,两回都遇上同一位负责打针的工作人员,都在45分钟内解决。

打针后到休息站坐下来观察半个小时,点名领取打针证明书后就可以离开。

第一回过了一夜后,打针的手臂开始轻微疼痛,不过并非不举的那种,一两天便恢复正常。第二回的情形跟首回相似。

妻子打的是莫德纳(Moderna)疫苗,两针间隔一个月。打第一针后感觉身体发热但体温正常,一个星期后打针的手臂局部发热肿胀,三两天后消退。

 

mRNA的原理

两针辉瑞疫苗的技术原理是这样的:通过信使核糖核酸疫苗(mRNA)来指导细胞产生S抗原蛋白(SARS-CoV-2特有的一种刺突蛋白),使身体产生免疫反应,并将该信息保留在记忆中。临床试验的有效率为95%mRNA m就是messenger,信使了。

打第二针的目的是通过注射疫苗后续增强剂,让身体第二次接触抗原,从而激活第二阶段的免疫反应。

辉瑞疫苗必须稀释,稀释后的单剂量为0.3 毫升(ml),稀释剂 0.9%氯化钠注射液(0.9% Sodium Chloride),也就是每公升水溶液含9克氯化钠。氯化钠就是俗称的生理盐水或打点滴

mRNA疫苗必须储存在-80-60°C的超低温环境中。稀释后的储存温度为+2+30°C,必须在6小时内使用。

Modena的技术原理相似,不过单剂量为0.5 毫升,不需要稀释。临床试验的有效率为94%。疫苗储存温度为-25-15°C。第一剂被抽出后,药瓶的储存温度为+2+25°C,必须在6小时内使用。

 

传统疫苗的原理

相较之下,传统疫苗是先培育病毒或细菌,然后加热或用化学剂将其灭活,再将灭活疫苗注射入人体。

灭活疫苗的意思是使到病毒或细菌失去致病能力,但保留抗原性,跟流感和A型肝炎的疫苗原理相似。

中国科兴疫苗所采用的就是传统灭活疫苗技术,两剂的间隔为14天。

202112月辉瑞和莫德纳分别将疫苗的相关临床数据刊登在每周出版,权威性的《新英格兰医学期刊》(The New England Journal of Medicine),中国大力推销的科兴疫苗则没有这么做。

新加坡按照早前签订的合约,于2月份接收20万剂中国科兴(CoronaVac)疫苗。第三阶段的临床试验显示,巴西当地的有效率约50%,印尼65%,智利67%,土耳其83%。基于仍然缺乏完整数据,新加坡还没批准使用。

中国于315日公布对一些外籍人士放宽入境条例,条件是必须已经接种中国疫苗。虽然如此,这些入境的外籍人士仍需接受隔离。

现在新加坡居民可以选择到37个接种中心注射疫苗,其中辉瑞26个,莫德纳11个。如果科兴也批准了,您会选择哪种疫苗呢?


相关链接

Friday, April 16, 2021

将东陵福的旧时光化为永恒 Tanglin Halt

原文刊登于《联合早报》2021年4月13日 

踏出以蓝为主色的联邦地铁站,步行约5分钟便可抵达位于联邦通道第46-3座的 我爱女皇镇展览馆。那是民间组织我的社区My Community)向建屋局租用的店面,将一楼用作《光影·女皇镇》展览用途,展览内容每几个月更新。

(联邦通道第46-3座的“我爱女皇镇”展览馆。)

该店面原身为经营多年的美发室,灰白相间的小方砖是上世纪80年代以前十分流行的地砖款式,所反映的正是古朴的东陵福组屋区风貌。

(展览馆的原身为经营多年的美发室。)

印象中的东陵福是火柴盒组屋区。约半个世纪前,中三中四每个星期都有一天来到这里的东林工艺中学上工艺课。日后在杜佛路新加坡工院上课那三年,这里是必经之路。 十层楼的外表千篇一律,就像整齐排列的火柴盒,不过日久生辉,展现出岁月的芳华。

(东陵福是火柴盒组屋区。)

钢骨水泥需要生活故事来柔化。老居民谈到新婚后搬到十层楼,电梯门打开的那一刹那,掩着脸蹲在电梯里哭泣,怎么也不敢跨出第一步,说会从10楼掉下去;住了三年都不敢晾衣服,怕围墙会倒塌。跟邻居熟络后,彼此间也会发扬垂直甘榜的精神,譬如在门户永远打开的客厅设置钥匙柜,左邻右舍出门时免费寄放钥匙,家人就不用摸门钉了。一班老友甚至约法三章,搬到同一座新组屋重续前缘,陪伴对方白头偕老

东陵福组屋区整体重建,2021年是火柴盒最终消失的年份。《光影·女皇镇》的最新展览,我的社区组织居民,通过光影作为对曾经拥有的故乡表达关怀。

参与的居民定时接到通知接下来几天的摄影主题,譬如心仪的场所、怀念的食物、日常趣事等,然后各自构思相关的画面。结果发现大家都有心灵相通的集体回忆:东陵福小贩中心、小贩中心旁的小广场、低层组屋外的晾衣架、火车曾经川行的昔日轨道等。

(东陵福小贩中心。)

(火车曾经川行过的绿色廊道。)

捕捉画面所使用的镜头不是智能手机,而是匿迹多年后重出江湖的柯达傻瓜菲林相机,菲林为36+3,幸运的话可以冲洗39张照片。从前非数码化的日子,我们使用傻瓜相机得心应手,如今智能的年代,负责人反而必须教导居民如何使用。

就如会场墙壁上的语录:日常生活就是这样我们每天看到的东西,也许哪一天就突然消失了,找不回了。你知道吗?再过几年这里的变化更大。也许会有摩天大楼,又或者女皇镇地铁站不再是蓝色的。谁晓得啊!民间组织缺乏资金,必须通过巧思来保留老地方的情感与记忆。主办方的用心良苦,居民的自愿参与,情义两相坚。小展厅所隐含的朴素人性,值得大大的赞!

(我们每天看到的东西,也许哪一天就突然消失了,找不回了。)

相关链接

Friday, April 09, 2021

风行一时的“十二支” (Chap ji kee)

“十二支”曾经在民间风行,属于非法赌博。

十二支的迷人之处,在于星期一至星期五都开“真字”,而且赌本不大,一毛钱就可下注了。星期六和星期天不开彩,保留给赌马和万字票。

十二支的号码有两个,从一到十二。投注方式分为“直落”和“排排坐”,直落就是投注的时候必须直写,跟开彩的号码顺序才能中奖;排排坐的话就不一样,只要两个号码都开出来就能中奖了,不需要顺序的。打个比方,下注的号码为八-六,开彩的号码为六-八,买直落的话就没中奖,排排坐则中奖了。

下注的金额是以符号代替数目字,o=一角,四个o=四角。〇中间加一划(Ø)代表五角,〇中间加个X代表一元。

赔率方面,每一角钱直落赔10元,排排坐赔5元。

下注时还必须注明买哪个“厂”。十二支有两个“厂”:“老厂”和“新厂”,也叫“大坡大同”和“小坡大同”。可以写“老”、“新”、“大”或“小”。

符号和“老新大小”都是十二支厂的暗语。


(此人下注的是老厂,也就是大坡大同。开的是八--六,四对字中了两对:其中一对是直落$1.20,赔$120;另一对是排排坐$0.70, 赔$35。总奖金$155。)

过去深受老人家和妇女欢迎


这类小本非法赌博,通常由老人家和家庭主妇出马投注。我小时候,左邻右舍每晚都会买十二支,使用一张小纸条,写上投注详情后,将钱交给我的阿嫲。阿嫲带着我散步到福南街口的糖果摊,假意买糖吃,实际上是悄悄的把下注的纸条和钱塞到女摊贩手中。

下午两点过后,阿嫲则带着我回到糖果摊,女摊贩轻声耳语,告诉阿嫲中奖号码,有时会暗地里塞一些钱到阿嫲手心。回到家后,有钱分的左邻右舍就会很开心,有些则捶心肝,说早知道….

两个厂的“庄家”都不会露面,而是由爪牙代劳,从新加坡各地收全所有的纸条后,隔天大清早私下开彩,看哪一对号码的赔额最低就开那一个。庄家是包赚的,这是公开的秘密。测中两个直落号码的概率为1/144=69/10000,比万字票的23/10000高出三倍,排排坐则高出六倍。由于十二支的中奖率较高,因此小市民不介意花几毛钱开心一下。


十二支的源头


根据何盈的《说黑道白》(玲子传媒,2014年),十二支源自清末的“字花”,19世纪初由华工带过来。1986年的警察月刊专文,则揭发十二支的赌法来自柔佛,由公开的开字转变为秘密开字,通过不知名的豆干小贩引进新加坡。

老厂早在1920年代已经颇有名气了,日据时期严禁赌博,大家怕被砍头,老厂逐渐衰落。二战结束后由另起炉灶的“上海蔡”自创“上海大同”,势力遍及全新加坡,不过被手下出卖,上海蔡夫妇被逐出境。

经历过一些其他事变后,十二支集团分厂,以新加坡河为界,福建帮为首的地头在南岸,叫“大坡大同”,福清帮为首的在北岸,叫“小坡大同”。这就是我的童年时代所知道的老厂和新厂。

行家爆料,从前的私会党“18”有约20个支派,由古老的义兴公司分裂出来。其中一个支派“十三幺”掌控包括十二支在内的赌博活动。以此推论,十三幺可能是大坡大同那一脉。

扫荡行动


当局不可能不知道谁帮忙收十二支,谁非法下注。擒贼要擒王,捉个小摊主、家庭主妇或老太婆,可能是自己的妈妈,邻居的外婆,又有什么用呢?

1968年连续六个月的大扫荡,十二支集团元气大伤。原来在那个年代,十二支厂每天到手的金额不少过30万元。[1]

十二支厂并没就此寿终正寝,而是转换经营方式东山再起。2004年,警方再次扫荡波东巴西、武吉巴督、武吉班让、红山、中峇鲁和新民路的十二支厂,调查显示总部设在波东巴西的双层公寓式组屋。每天的赌注为20万至40万元,年营收超过一亿元。[2]

这么大的肥羊,难怪还是有人铤而走险。


[1] Stella Danker, “The town’s biggest cheap thrill is all but buried”, The Straits Times 27 July 1986.

[2] Jose Raymond, “Cops cripple chap-ji-kee syndicate”, Today 3 Sep 2004.

相关链接

Friday, April 02, 2021

长堤的邻居 ——支那河溯源

原文刊登于《联合早报》202134


刘培芳去年1015日在《四方八面》发表《一条河的名字》,文中提到长堤东面有条支那河,从海军部公园流经兀兰滨海公园,于柔佛海峡出口。

来往新柔长堤数十年,从没留意过支那河。新关卡未落成前,长堤上吸引眼球的是西面濒海搭建的浮脚楼,细长木板桥贯穿多户人家,年轻的妈妈围着纱笼,跟小孩泡在水中嬉戏,人与大自然融为一体。

长堤东面高耸的马西岭点式组屋,跟西面简朴的马来风光形成强烈的对照。

(拆除前的甘榜罗弄花蒂玛,背景为马西岭的点式组屋。From Yeo Hong Eng collection, photographer unknown.)

消失的甘榜罗弄花蒂玛

位于长堤西面,称为甘榜罗弄花蒂玛(Lorong Fatimah)的水乡,消失的年份并不久远。上世纪80年代末拆除时,傍海而居的村民搬迁到附近的组屋。有些老人家对生活一辈子的地方依依不舍,当局特别通融三个月,让他们沉淀心情。日后新的关卡大厦坐落在甘榜原址上。

跟此马来渔村邂逅的时候,各家各户门前都有艘小舢板,随着波浪摇晃起伏。严格说起来,马来渔村存在新马自由通行的年代,木船一物二用,捕鱼之余亦充作渡海小舟。使用蓝色护照过长堤的时候,村民已经摆脱渔民岁月,像华人的孩子一样,到学校、工厂、办公楼工作,闲来无事才划着小艇,捕条鲜鱼为餐桌加料。

甘榜罗弄花蒂玛全盛时期有400多居民,由于受到新马合并与分家的牵连,同屋檐下的父母子女,莫名其妙地分别拥有不同的国籍,正好印证新马民间密切的关系。

老居民对从实里达岛移居到柔佛南岸的实里达人记忆深刻。传统弄迎舞(ronggeng)是甘榜节庆必备的项目,这些世代在船上生活的海人,看到甘榜灯火辉煌,马上带齐铜锣手鼓等乐器,跨海前来助兴。印度摊贩消息灵通,骑脚踏车运来一箱箱的衣物、纱笼、毛巾和日用品,跟华人演街戏的热闹场面何其相似。


支那河畔的华人村庄

谷歌导航下,终于跟咫尺天涯的支那河会晤。绿意盎然的小河距离长堤700多米,出海口只约10米宽,难怪在长堤上眺望时会错过。古今地图所提供的线索,可让我们还原小河的百变浮生:

一、1828年第二任驻扎官哥罗福发表的Franklin and Jackson图:这是英国人制作的第一幅新加坡地图,标志着岛上的主要河流,不过图上没有支那河。

二、1850年代新加坡地图(Map of the Island of Singapore and Its Dependencies):这幅地图出现支那河(S China)、陈厝港、刘厝港、巫许港和烂土港等字眼。

三、1873年新加坡地图:图上清楚描绘河流的位置,甘蜜港区和主要道路。长堤旁的马西岭组屋坐落在昔日陈厝港原址。

(19世纪图:支那河与陈厝港。长堤旁的马西岭组屋坐落在昔日陈厝港的原址。)

四、1911年新加坡地图:这些港区都消失了,标志着甘蜜出口王国的终结。

五、1924年测量图(Federated Malay States Surveys Number 7):陈厝港原址出现汉口(Han Kow Estate)和晋江(Chin Klang Estate)两个新地名。

六、1945年的地图:汉口依旧在,晋江则消失了。

七、1969年新加坡街道图:第115图显示支那河上游有个甘榜双溪支那Kg Sungei China)。根据老街坊反馈,甘榜的居民主要是华人和少数马来人。新加坡独立前,他们甚至每天早晨骑着脚踏车到新山买菜,顺便吃早餐。

八、2020年公园局地图:公园局在兀兰滨海公园设置的地图,将这条小河命名为Sungei Cine。以Cine取代China,因为支那这个中性词,在二战之后被普遍认为是日本军国主义者侮辱华人的词汇。

(20世纪图:支那河畔出现汉口,甘榜双溪支那和罗弄花蒂玛。)

支那河畔的历史沿革

通过支那河的命名与周遭的环境变迁,可见自开埠初期创建陈厝港以来,支那河畔已成为华人先民的落脚处。早年先民择地而居,河流、水源是首要条件。至于二战后出现的甘榜双溪支那,命名跟古老的小河关系密切。

昔日乡村遍布全岛,地处兀兰16英里的甘榜双溪支那只是个寂寂无闻的芸芸众村之一。翻阅多份中英文报章,只在1973年初的报道出现该村落的踪迹。当时淫雨霏霏,200多居民被疏散到高地,儿童不识愁滋味,兴高采烈地戏水取乐。不久后,这里成为马西岭组屋区。

(绿意盎然的支那河)

顺道一提,支那河畔陈厝港的港主是陈开顺19世纪中叶,天猛公伊布拉欣借鉴本地的甘蜜与胡椒经济效益,在柔佛推行港主制度。陈开顺获得地不老河(Sungai Teberau)的港契,率领潮州弟兄渡海开辟另一个陈厝港。他们一行人接着将新山打造成行政区,恭请天猛公迁都,从此奠定义兴公司在柔佛的至尊地位。目前友诺士一带的普照禅寺所保管的70多座反清义士神主牌,候明义士陈开顺(号贞国)乃其中之一,因此不排除他为了避难才逃到南洋的。

支那河名称起源于两个世纪前华人先民沿河垦荒,竟然延伸至长堤对岸的发展,两岸的生命脉络细水流长。

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