Occasionally a shipowner undertakes to carry an exact cargo size – e.g. ‘40,000 tonnes minimum/maximum coal in bulk, stowing around 47 cubic feet per tonne’ – but often a margin is negotiated to enable a master to maximise his ship’s lifting (which will vary depending upon the quantity of bunkers she has on board) – e.g. ‘40,000 tonnes coal in bulk, 5% more or less in owner’s option’. It may be that this margin is at ‘charterers’ option” although such an arrangement precludes the certainty that the vessel’s master can maximise his cargo lifting, and means that the owner must estimate on the minimum cargo quantity when calculating the viability of such a prospective future. Where a shipowner contracts to load or a charterer to provide about a certain quantity – e.g. ‘about 10,000 metric tonnes bagged fishmeal’ – the word ‘about’ is construed to mean within, say, a reasonable margin of (say) 5%; in other words, between 9,500 and 10,500 tonnes. However where the word ‘about’ is replaced by ‘without guarantee’ it means just that. There is ‘no guarantee’ and the cargo can legally be of any size. Occasionally a stated margin is agreed – e.g. ’30/32,000 tonnes’. Here it is understood that the cargo to be loaded and/or supplied will be between 30,000 and 32,000 tonnes of cargo and, to make matters absolutely clear, the words ‘minimum/maximum’ or similar might be added – e.g. ‘within 30/32,000 tonnes min/max’ whilst the additional phrase ‘in owners/shippers’ option’ defines whose right it is to decide upon the exact cargo quantity within the agreed limitations. While an owner will usually be looking to maximise a ship’s intake there are other elements to consider. On no account must the ship’s maximum dwt be exceeded, nor must the loadline be submerged at any point during the voyage. Remember that even if a ship starts its voyage in a zone where cargo intake can be maximised, the ship may have to pass through another zone during the voyage. Sometimes a ship may have to sail with empty holds for safety reasons because to do otherwise would mean part cargoes in one or more holds that might be liable to shifting.