There are only a few differences between voyage estimates for dry cargo ships and tankers. For those charters based upon Worldscale, the laytime calculation is easier as the scale allows for 72 running hours in aggregate for loading and discharging (‘all purposes’) and 96 hours total in port. An expense in tankers which does not occur in dry cargo involves the consumption of bunkers for ancillary purposes such as cargo heating, pumping cargo and tank cleaning. It is extremely difficult to assess bunker consumption for heating cargo depending, as it does, on the temperature at which the cargo is loaded, whether in wing or centre tanks and on the ambient temperature of the sea and air during the voyage. Only the technical department can give an accurate assessment for this purpose as, without their available statistics, it can only be sheer guesswork. Pumping and tank cleaning are easier, although again the technicians must be asked for an average consumption based on past experience. As the practice of charterers taking vessels on time charter for trips has become widespread, it is obvious that we need to estimate the daily profit on this type of fixture in the same way as a voyage charter in order to compare the two results. Merchants often prefer to take a vessel on time charter, either for a trip or period, as it gives them flexibility and also the possibility of reducing their costs. Fortunately this is a much simpler exercise if the ship is taken on delivery at the previous discharge port and redelivered on completion of the voyage in question, it is only necessary to deduct the Daily Running Cost from the hire earned per day to achieve the daily profit. Of course, commission must be allowed for and, should there be any difference between the charter price of bunkers paid by charterers on delivery and the actual price paid by owners, this must similarly be taken into account in the calculations.