SECTION 5 AN ALTERNATIVE APPROACH TO ANCHORING
第五章另一種拋錨方法
5.1 THE U – TURN METHOD
5.1 U形迴轉拋錨法
The U-turn or more precily, orthogonal method of anchoring has a long historical precedent and has been the practice of a number of masters for many years. Its benefits have also been discovered during emergencies when the master’s quick reactions and knowledge of how to lay anchor on the move have saved the day. However, prior to the mathematical and mechanical analysis carried out by Captain Allan McDowell, such a procedure could not become mainstream and owners would have been reluctant to incorporate it into their operational procedures.
U形迴轉法(又稱為Side-way method橫向拋錨法)更精確來說直角迴轉法，有長遠運用之歷史前例並已行之有年且經很多船長使用許久。其優點尤其顯見船長於緊急狀況下行進間拋錨來扭轉危機。但此法在未經Allan McDowell船長以數學及機械分析前並未成為主流之拋錨法且船公司較不願意納為一般錨泊操作程序書。
The procedure is not without risk and its success depends on the crew having a clear understanding of the procedure with appropriate training in the u of the equipment. Becau timing is critical, excellent commu合同模版
nications must be maintained between bridge and fo’csle. Masters and crews who have not ud this method before should ensure that adequate a room is available. With experience however, the manoeuvre can be safely completed within a relatively compact area.
此法並非毫無風險可言，其成功有賴船員對操作程序充分之了解，加上適當的訓練。因為時機為相當重要之因素，船頭與駕駛臺之連繫尤為重要。從未使用此法之船長及船員於嘗試首度使用時須要有足夠之海域供其拋錨。久而久之熟練後僅須相當有限空間即可為之。
5.2 AXIAL VERSUS ROTATIONAL FORCES
5.2 縱向軸力與旋轉力之比較
The cret of the U-turn approach to anchoring lies in parating the momentum of the ship’s hull from forces necessary to control the movement of the cable.
使用U形迴轉法來拋錨的秘訣是：使移動船體的動量移轉為控制錨鏈所需的力量。
Consider a block shaped vesl, it has a block coefficient of 1. The force required to accelerate the v
esl in the fore and aft line is three times that required to rotate it about its pivot point. That is why it is easier to push a
small sailing boat sideways or rotate it round it axis than move it in the fore aft 介绍信抬头
line.
一個方型船體的肥瘦係數是1。使船體作前後向加速所需的力量三倍於使其繞
迴轉中心旋轉所需的力量。這也就是為什麼將小帆船橫向移動或使其繞中心迴
轉較使其縱向推動容易的原因。
It follows that to decelerate the same block in rotation would be one third the force required to stop its axial momentum.
同理，使上述船體於旋轉中減速所需的力量僅為停止縱向運動所需力量的三分之一。
This difference is becau rotational inertia is less than the axial inertia; it is a change from straightforward linear acceleration to one of the angular acceleration. A further contributory factor is that in the latter, the distance from the axis of the centroid is part of overall equation, whereas in the former the distance from the axis of the centroi平面设计师
d does not enter into the equation.
其中之差別是因為旋轉運動的慣性小於直線運動的慣性，這是一種變化亦即從絕對直線加速度變為有角度加速度。另一個作用的因素是，在後者中，與軸心線的距離是構成力的方程式的一部分，但前者中，離軸心線的距離卻非構成方
程式的一部分。
However, a ship is not a rectangular block in plan view, but a diamond or lozenge shape. Taking this as the best fit shape, the block coefficient is not 1 but 0.5. The radius of gyration of the new shape is now one third that of the full box shape.
然而，一艘船以平面來看並非長方形體而是菱形，若將它視為是最適合之船型，則其肥瘦係數是0.5而左右为难
非1，這個新形體的旋轉半徑只有原來長方形體旋轉半徑的三分之一。
Since the radius of gyration is part of the equation which gave a one third reduction in force required to decelerate the box shape, then it follows that with a block coefficient of 0.5, the reductions is now one ninth. But the mass has now been halved, so the factor of 9 must also be halved, giving a final figure of 4.5. Thus for a block coefficient of 1, it is 3. The ship shape lies somewhere between the two and can be assumed to be equal to 3.5.
因為在力的方程式中用到了旋轉半徑，使菱形船體減速所需的力僅為長方形體所需三分之一的力，其結果是肥瘦係數為0.5的船體，所需的力減為九分之一。但因為重量亦減半，所以九亦應除以二，得到4.5。因此之故，當肥瘦係數為0.5時，力的折減因數為4.5，肥瘦係數為1時，力的折減因數為3。船的
實際肥瘦係數介於二者之間，力的折減因數約為3.5。
Instituting a turn at the point where the anchor is let go will change the force on the cable from one of axial translation to one of rotational translation. But one of the factors of rotational inertia is the distance from the axis through the centroid. By using the anchor and cable this distance has now been incread by the length of the cable, a factor of 6.5. By applying the two factors (3.5 X
6.5) one finds the force on the cable is approximately 23 times less than the original ca!
在抛錨點轉向會使錨鏈受力由前後軸向運動轉變為旋轉運動。但是旋轉慣性的因數之一是距離軸心線間的距離，藉由使用錨和鏈，因而距離隨錨鍊長度增加，力的折減因數是6.5。應用這兩個因數（3.5 X 6.5），錨鏈受力折減至約為原來的1/23。
Clearly, keeping the cable at right angles to the hull greatly reduces the likelihood of extreme forces being applied to the anchoring equipment which is why the U-turn method is very much safer and is
associated with far fewer accidents. When the cable is at 90 degrees to the fore and aft line, fore and aft movement does not affect the tension of the cable, or only minimally. In this way, it is very difficult to exceed the forces that one is trying so hard to avoid with the fore and aft method.
很明顯的，使錨鏈方向和船身成直角可以大量減少錨具過度受力之可能性，這就是U形迴轉法較為安全，事故較少的原因。當錨鏈與船前後向成直角時，錨鍊所受之張力幾乎不受船前後移動之影響。如此操作，錨鏈受力極不可能超過吾人於傳統式縱向拋錨法中力求避免的強大拉力。
This technique is also more forgiving should the master have misjudged the speed and is moving too fast and especially in the event of engine failure during the anchoring procedure. This is quite impossible using the traditional fore and aft method. Having the skill to anchor a vesl which is moving is one that can save the ship, possibly your life and your job!
當船長錯估了船速，船舶移動過速或下錨中主機故障時，使用這種技術更為需要。這在使用傳統式前後向下拋錨是不可能做到的。吾人如具有這種在船舶移動時下錨的技術便可拯救船舶、人命或是你的飯碗。
SECTION 6 USING THE U-TURN METHOD
第六章使用U形迴轉拋錨法
The anchor and gear is prepared as for any normal anchoring. The windlass is tested in both directions, the locker checked for obstructions, the dog clutch engaged, the anchor walked out clear of the hawpipe, brake on, bow stopper/compressor on and clutch out. The master should always take personal responsibility for the checks.
如同一般錨泊備妥錨及屬具。測試錨機正、反轉, 檢查錨鍊艙出口有無障礙，離合器卡上, 錨鍊絞出至錨鍊口，鎖緊煞車、放下錨鍊阻擋桿，脫開離合器。船長應親自負責上述檢秋天的景色作文300字
查事項。
6.1 OPERATIONAL BRIEFING
6.1 任務簡報
Before the anchor is to be let go, there need to be tow pre-operational briefings. The first briefing is a training ssion to ensure that the personnel concerned know exactly how the equipment works and should be ud. The cond briefing is just before anchoring, to ensure that the crew understands that:
在拋錨前須做兩次任務前簡報。首次為熟悉訓練以確保作業人員確實了解如何操作錨具設備及原理。第二次為在面臨拋錨前以確定船員了解下列事項:
SECOND BRIEFING
第二次簡報
●On large ships there should be ideally be two men on the brake since the
rated force cannot be applied by one man alone.
大型船舶理想上應有兩人來操作錨鍊煞車因單人無法應付額定的制力。
●The anchor will be lowered under power to 汪国真的诗
an ordered number of
shackles on deck, say two, prior to taking out of gear and 无伴奏
letting go on the brake.
以錨機將錨鍊鬆出至幾節在甲板，比如說兩節，然後脫開離合器，鎖緊煞車準備下錨。
●When the cable is relead, the cable will be let out in controlled manner
so that each link can be followed with the eye.
以可控制的速度鬆出錨鍊以便能以眼識別錨鍊鬆出節數。
●The cable is kept running out until the desired length is all out, which
avoids the brake fade caud by the more common practice of stopping and starting.
以煞車控制錨鍊鬆出的速度直至所需的長度為止，但須注意勿過度磨損煞車
皮。
●When the cable is out at the desired length, the cable is stopped from
moving by the brake then the bow stopper is put on. The safe尿裤子作文
pin is fully engaged whilst the cable is stopped and still vertically up and down.
當錨鍊以煞車鬆至所需的長度且停止不動、錨鍊成垂直狀態時，放下錨鍊阻
擋桿後將安全插梢完全插入。
●When the bow stopper is on, the bridge is to be kept informed of the
direction of the lead on the cable which must be kept on the beam until all movement has cead. Only then the cable be allowed to draw slowly ahead.
當錨鍊阻擋桿放下後，應將錨鍊的方向隨時告知駕駛台，此時錨鍊應保持於正橫的方向直到船舶停止不動。唯有在這個時候錨鍊的方向才能慢慢朝向船艏。
If the bottom is known to be very deep, or particularly rocky, it would be prudent to walk the anchor out until just clear of the a bed.
如遇海底為深水或為特殊的多岩底，為謹慎起見，應將錨鍊以錨機鬆至海底上面元宵节的来历简介
為止。
6.2 APPROACH TO ANCHORAGE
接近錨地
The objective is to let the anchor go with the bow moving sideways over the a bed at about 0.5 knots. The actual speed of the bow may be much greater by this method and the manoeuvre has been successfully accomplished by Captain McDowall at speeds of up to 4 knots ahead whilst turning. The turn will always stop the ship. In cas where you cannot afford to wait, some forward speed can be accommodated, provided the cable is kept on the beam. The sideways movement is very slow.
目標是以離地面0.5海浬真正速率迴轉船艏來拋錨。使用此法時實際速率可能更高, McDowall船長曾以高達4海浬之速度成功的使用此法，於船舶迴轉中拋錨。船舶迴轉總能讓船舶停止。尤其是當船舶無法等待之情況時，在某些船舶前進速率亦可達成惟必須將錨鍊保持於正橫的方向。船舶的橫向運動是相當緩慢的。辣椒土豆丝
Using the rever of the normal approach, steam the vesl into the anchorage downtide/wind with minimum steerage way, that is with engines stopped and steerage being maintained by short bursts of ahead power.
