what distinguishes a whaling ship from other ocean vessels in regards to their supplies

From the text:

"While other hulls are loaded down with alien stuff, to be transferred to foreign wharves; the world-wandering whale-ship carries no cargo but herself and crew, their weapons and their wants. She has a whole lake's contents bottled in her ample hold. She is ballasted with utilities; not altogether with unusable pig-lead and kentledge. She carries years' water in her. Clear old prime Nantucket water; which, when three years afloat, the Nantucketer, in the Pacific, prefers to drink before the brackish fluid, but yesterday rafted off in casks, from the Peruvian or Indian streams. Hence it is, that, while other ships may have gone to China from New York, and back again, touching at a score of ports, the whale-ship, in all that interval, may not have sighted one grain of soil; her crew having seen no man but floating seamen like themselves. So that did you carry them the news that another flood had come; they would only answer -- 'Well, boys, here's the ark!'"