In one of the previous sentences, the indefinite article en is omitted ("Jag har bil"). Would it be possible to omit en here too? Wouldn't "Min morbror har en stor båt" emphasize that the number of large boats he has is one, while "Min morbror har stor båt" merely implies that he has a large boat in general?
With an adjective, you can leave the article out for things you're supposed to have. Like a nose. Min farbror har stor näsa sounds much better without the article. But har stor båt sounds a bit odd, as if it were a body part or like it was really taken for granted that he'd have a boat in the first place.
I have heard somewhere that in Swedish there's a difference between «på båt» and «i båt». The first one means a large boat, like ship. And «i båt» means just little boat... So, is it true? Is there this difference in Swedish?