When a ship is transiting a canal or a narrow waterway, a ship may run on diesel oil in the main engine. Diesel oil more expensive and higher quality than heavy fuel oil. On the other hand, diesel oil gives more immediate engine response to navigation maneuvers. In canal or a narrow waterway, a ship proceeds slowly and burn bunkers (fuel) more economically. Therefore, it may be necessary to estimate normal speed and consumption to and from either end of the canal, adjusting time and consumption appropriately. Furthermore, port charges cannot easily be assessed without experience and most companies will keep records of previous calls to assist them. BIMCO and INTERTANKO provide valuable information on many ports but probably the most accurate method is to contact an agent at the port in question with basic details of the ship asking agent to give a Proforma Disbursement Account (Proforma DA). Ethically, same agent should be appointed, if the ship is fixed for the voyage in question. In same manner, canal dues are usually fixed on the basis of the ship’s Canal Tonnage (Suez Canal Tonnage or Panama Canal Tonnage), as the canal authorities in question tend to add in more cubic earning spaces when canal authorities grant the ship Canal Certificate. In voyage estimations, estimator should keep in mind that, mere calculation of the canal dues payable is not be enough, as extras will mount up for such as agency and towage.