Fathoms are usually used for depth. I'd be more inclined to use leagues, which, when used at sea, in the English-speaking world, are usually three nautical mil

Fathoms are usually used for depth. I'd be more inclined to use leagues, which, when used at sea, in the English-speaking world, are usually three nautical miles or five point five five six kilometers. So about 5.39 leagues across. Since we use ships when we go to space and sea, I like the idea that space ships are naval.