Economies of scale. Think about the Portuguese caravels that were first to circumnavigate the World, and how tiny they were (roughly 100 tons). We don't bother

Economies of scale. Think about the Portuguese caravels that were first to circumnavigate the World, and how tiny they were (roughly 100 tons). We don't bother with such small ocean-going ships today because they are too uneconomical to use. We use ships today that are a thousand or more times larger - around 200,000 tons.