共同海損法可能是起源於2500年前之衡平的國際海法；其目的是處於海上共同危險時，在各方利害關係人之間，為了共同利益，就保存之財產依比率分擔，由一方或多方之自願犧牲與所發生之費用。 一旦共同海損滅失及求償總額已經決定了，即產生了下列問題。即船舶在什麼基礎上來計算分擔價值呢？ 依據2004年約安規則G，「共同海損損害額及分擔額之計算，應以冒險終了時及地之價值為準。」約安規則17也有類似的規定。 本文作者討論了船舶分擔價值如何估算，並建議我國海商法第111條、112條、113條應修正。

General average law originated probably some 2,500 years ago as an equitable and international “law of the sea” for the purpose of sharing on a rateable basis between all the parties to a common adventure those sacrifices and expenses voluntarily made or incurred at a time of peril by just one or a few of the parties, for the joint benefit of all. Once it has been established that a genera average loss has occurred and the amount to be made good has been determined, one question arises: On what basis should the ship's contributory values be calculated for those interests called upon to contribute? According to RULE G of 2004 York-Antwerp Rules, “General average shall be adjusted as regards both loss and contribution upon the basis of values at the time and place when and where the adventure ends. “RULE 17 has almost the same word. In this Article, the Author discusses how to evaluate the ship's contributory values, theoretically and practically, including the actual net values, etc. The Author suggests that article 111, 112, 113 of the Maritime Law of the Republic of china be amended.