The Association is grateful to Andrew Fox of Davies Johnson & Co for contributing to this update. In order to avoid risks of disputes as well as missing time bars, Owners should seek to have charterparty and bill of lading clauses expressly choose one set of general average rules to the express exclusion of the other. Background: General average General Average (GA) is an ancient concept of maritime law, dating back to ancient Greece and founded on equitable principles. The basic rule is well stated in a vintage English decision, as follows: '... all loss which arises in consequence of extraordinary sacrifices made or expenses incurred for the preservation of the ship and cargo losses ... must be borne proportionately by all who are interested.' (Birkley vs. Presgrave 1801) This is further explained in the key tome to general average in " Lowndes and Rudolf: The Law of General Average and the York-Antwerp Rules ": "The rule of a general contribution, by rendering it immaterial whose property is taken in the first instance and material only that that should be taken which will most surely and effectually, and at least cost, save the whole, does away with [any] conflict in the captain's mind between interest and duty, leaves him alone with purely nautical considerations, and thus, no doubt, does more than any statesman or philanthropist can effect for the preservation of life and property at sea. The utility of the rule of General Average no doubt explains its universality and permanence." Furthermore, in order to have a general situation, it is usually taken that there was an  extraordinary sacrifice or expenditure  which was incurred for the  common safety  or the  preserving from peril  of property involved in a  marine adventure . The York Antwerp Rules 1994 and 2004 General average is often "adjusted", i.e. : the calculation of what costs go "in" and shared by "whom" and to what "percentage", on the basis of one of two sets