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航海技術討論版

航海學 吃水問題

dragon
2016-04-15 02:01 #
某船夏季滿載吃水為9.5M, 該船船長規定該船的最大吃水不可超過9.5M, 否則不符合LOAD LINE規定. 比如船頭吃水9.0M, 船中9.5M, 船尾10.0M, 該船長表示最低乾舷已不足, 不符合規定. 所以滿載就一定要調成船頭9.5M,船中9.5M,船尾9.5M.
本人向該船長表示, 書中FREEBOARD指的是船中乾舷, 而不是船尾, 只要船中吃水沒有超過限制, 船尾吃水多少都沒問題. 但是由於本人學藝不精, 又實在不是讀書的料, 想要說服船長, 又找不到相關依據. 看LOAD LINE看了半天, 也沒看出什麼結果, 沒看到書中提及船頭船尾吃水限制, 說的都是船中乾舷, 有找到以下文字,
The ship is loaded to its Summer Load Line on an imaginary even keel.
船長將此文句解讀為」 滿載就一定要平吃水.」, 否則就超過最低乾舷.
我的解讀為」船舶依據其夏季載重線,假設為平吃水狀態裝載.」, 以得到船中吃水, 而非滿載就要平吃水.

所以想請大家幫忙小弟解讀以上英文句子, 或大家能找出LOAD LINE中任何依據, 以讓本人能說服船長, 只要船中不超過夏季滿載限制9.5米, 船尾吃水10米是沒有關係的.

如果船中不超過9.5米沒有超載, 那船尾最大吃水有無限制? 假設能不能調成船頭8.5米, 船中9.5米, 船尾10.5米?

懇請大家協助小弟解讀以解決疑惑. 小弟感激不盡!
Nazi
2016-04-15 00:25 #
這個問題非常好,先跟您說結論,結論是您是對的,貴輪船長對Load Line有點誤會了,
希望您可以好好地去和他溝通,首先,您在Load Line公約裡面找不到相關規定是因為用錯關鍵字了,
在Load Line公約裡面有關這個部分是在第12條的Submersion,這條有三項規定如下,

(1). Except as provided in paragraphs (2) and (3) of this Article, the appropriate load lines on the sides of the ship corresponding to the season of the year
and the zone or area in which the ship may be shall not be submerged at any time when the ship puts to sea, during the voyage or on arrival.
(2). When a ship is in fresh water of unit density the appropriate load line may be submerged by the amount of the fresh water allowance shown on the
International Load Line Certificate. Where the density is other than unity, an allowance shall be made proportional to the difference between 1.025 and the
actual density.
(3). When a ship departs from a port situated on a river or inland waters, deeper loading shall be permitted corresponding to the weight of fuel and all
other materials required for consumption between the point of departure and the sea.

第一項規定了超載的定義,簡單的說就是在任何時刻,船兩側的所相對季節或區域的載重線都不能被淹沒,
第二項及第三項講的是海水密度以及內河或內海的額外規定就不特別說明了,
而澳洲的MO16內的23A也規定了超載的定義如下,

23A Meaning of overloaded

23A.1 For paragraph 113(a) of the Navigation Act, this section sets out the circumstances in which a vessel is overloaded.

23A.2 A vessel is overloaded if the appropriate load line would be submerged if the vessel were floating without a list in still salt water of a specific gravity of 1.025.

23A.3 A vessel is overloaded if:
(a) it is engaged on, or is about to engage on, a voyage during which a load line other than the appropriate load line would, at some later time during the voyage, become the appropriate load line (the second load line); and
(b) the second load line would be submerged if the vessel were floating without a list in still salt water of a specific gravity of 1.025 and the fuel and other material that would normally be consumed or discharged before the second load line became the appropriate load line were unloaded from the vessel.

23A.4 A vessel is overloaded if:
(a) it is a passenger vessel; and
(b) the appropriate subdivision load line would be submerged if the vessel were
floating without a list in still salt water of a specific gravity of 1.025.

23A.5 For this section, the appropriate load line or appropriate subdivision load line is
determined in accordance with section 23

其中23A.2也清楚表示超載就是在假定1.025的密度且船無傾側的狀態下Load Line被淹沒,

綜觀以上,船舶是否超載一切都是以有沒有淹沒Load Line為主,就是船舯左右兩舷的載重線標誌,
沒有提到前後水尺,更沒有提到實際載重噸數,
所以超載並不是以超過某一個吃水(Draft Mark)或載重噸為準的,
只是在實務上,Load Line往往會因為密度的關係而被淹沒,所以大都是以Draft Survey的方式來計算判斷,
而不是以現場看為主,而為了方便計算,大都會把船調整成even keel,
本人在澳洲裝貨也是以此原則下去計算開航吃水,在當地水道餘裕許可之下,
不一定要even keel,船艉吃水可以多一點,只要船舯水尺沒超過即可(換算成1.025),
但是這裡要注意船體變形量的問題,Draft Survey的方式大都是計算至Quarter mean,
這是用來計算排水量及貨量用的,並不能拿來當作是否超載的定義,
公約及法規規定都是以Load Line現場標示為主,並不能把船體變形修正量放進去,
當船舶中垂時,當你裝到可以裝載的最大吃水時,你船舯的載重線標誌已經被淹沒了,
本人在幾年前在南澳裝載穀物時AMSA就僅以船舯左右兩點吃水平均回推1.025海水密度來計算本輪是否超載,
另外也要注意船舶傾側,有的國家及港口是可以接受使用船舯左右兩點吃水平均值,
但是有些就不行了,左右任何一點超過都不行,這點可能要事先問清楚,
最後想提醒您的,超載會比少裝來的麻煩很多很多,很多地方是僅能裝貨不能卸貨退貨的,
一旦發生超載的情況,除延誤船期外還需特別請額外裝備和駁船過來運走,
公司花費會比Dead Freight多很多,可以的話還是給自己留一點空間吧,
另外回答您最後的問題,船艉最大吃水的限制在於裝卸貨港口本身的限制,
也就是只要不要裝貨港出不去和卸貨港進不去(需考慮當地港口海水密度)之下,
船舯不要超過載重線,你高興調成多少就多少,希望以上可以解決您的疑惑。
dragon
2016-04-15 02:01 #
感謝您熱心且詳細的回覆. 您說的非常正確,人與人之間相處,必須好好地溝通才行.