Approximately a third of the voyage remains at Cape Town, and a third of the total fuel oil required – 689 tonnes (2068 ÷ 3) – would save the ‘CURLEW’s operators about $13,750 (689 x $20). Port costs at Cape Town will be about $2,500, the deviation is barely noticeable, and the delay to be expected only about half a day. Consequently, it must be worth calling at Cape Town for fuel oil, since the daily voyage value is very unlikely to reach $22,500 ($13,750 -2,500 = 11,250 x 2 half days) on this particular voyage. Not only that, extra cargo can be taken at Newcastle, and if bunker prices at Rotterdam show signs of increasing by the time the vessel reaches Cape Town, extra bunkers can be purchased. So we take sufficient bunkers at Osaka safely to reach Cape Town via Newcastle, and there the balance safely to reach Rotterdam. But what about our safety surplus? Study the atlas. There is no need to take safety surplus for the Osaka/Newcastle leg. If the worst comes to the worst after a difficult ballast voyage, extra bunkers can be taken alongside at Newcastle. It is assumed in estimating that a safety surplus will not necessarily be used. It must be allowed for in the calculation of cargo intake, etc. but not costed as one cannot be certain it will be used but will be taken forward to the next voyage in the form of a credit. (This estimate is slightly unusual as we are assuming the vessel is completely empty of bunkers at the start of the voyage in Osaka). Thus one can expect that the safety surplus of 120 tonnes f/o and 6 d/o will remain on board upon arrival at Cape Town. Since the voyage leg from Cape Town to Rotterdam is less than from Newcastle to Cape Town, there is no need to take any further safety surplus supplies at Cape Town, but simply to cost the extra bunkers required to reach Rotterdam – some 19 days away.