Marlon told Csongor about what Batu had said regarding the fuel gauge, or lack thereof, and so Csongor went down to the engine room and spent a while figuring out how the diesels worked, eventually identifying the fuel line and the pump that fed it. From this, plumbing led back through a bulkhead to a space mostly occupied by a pair of cylindrical tanks of impressive and reassuring size, each rather more than a meter in diameter and perhaps three meters long. Each had a fill pipe welded into its top. Csongor traced those up to a pair of fittings on the deck, which he guessed they would use whenever they pulled up to the nautical equivalent of a gas station. Shining his flashlight around that area, working out slowly in concentric circles, he finally found where they kept the dipstick: a piece of (inevitably) bamboo secured under the gunwale with bungee cords, ruled with felt-tip scribe marks and (to him) cryptic annotations. He called Yuxia down to help him interpret the marks, and then they opened one of the fuel fill hatches and shoved the bamboo pole down into it. Then he began pulling it out in a hand-over-hand movement, praying that he would feel cold wet diesel fuel on his palms. This did not happen, however, until the last few inches of the stick emerged. Yuxia read the nearest number marked on the pole. This meant nothing since they had no idea how quickly the diesels consumed fuel. But there was no ignoring the fact that it was the last number on the stick. "We just have to be scientific about this," Csongor said, and he marked the exact location of the fuel level and noted the time.