Canal Tolls

We have already calculated Madagascar to Mauritius and port time there.  We are told the distances from Port Louis to Durban and from Durban, via the Cape of Good Hope, to London (Silvertown), and can base time and consumption on this information.  We are, therefore, left once more with the problem of estimating port time in London.  In order to do this we must again first calculate cargo intake. The sea distance from Durban to London is by far the longest of any leg in either voyage alternative – some 22 days at 13 knots, weather permitting.  Thus it follows that bunkers remaining on board at the commencement of this leg will be greater than for any other leg and will consequently affect the maximum cargo quantity which can be allowed on board at that point.  So although the vessel can load more cargo than would be required at Mauritius, we must remember always that her summer freeboard must not be submerged at any stage of the journey.  If she loaded to her full marks at Mauritius she would be overloaded when taking on necessary bunkers at Durban. So Durban sailing on summer marks is the restricting factor in this part of the estimate.  Durban is located in a permanent summer loadline zone so, as in the first alternative, since she would then proceed to London in either summer or tropical zones, there are no restricting factors of this nature. Port and transit expenses are similar to the first alternative, except that Suez Canal tolls are avoided but, instead, Durban calling costs are included. Despatch is also similar, the difference in the cargo loaded making only minor effect. Obviously, the additional steaming time is reflected in extra bunker consumption.  Once again the 300 tonnes fuel oil and 40 tonnes diesel oil remaining on board at the commencement of the voyage must be costed at $70 and $145 per tonne respectively.  But to this must be added the balance of fuel oil and diesel required to reach London at the Durban prices of $85 and $325 respectively. The smaller cargo reflects a marginally lower income of $289,162, but this is offset by these reduced cargo expenses to leave an increased gross voyage surplus of $150,436.  This voyage, however, will take longer than the route via the Suez Canal.  Nevertheless, the net result still works out more profitably via the Cape by an increased $100 a day, or so, on the gross daily income – $150,435/59 = $2550 (as against $2437).