Towards the end of the 14th century, ships like the carrack began to develop towers on the bow and stern. These towers decreased the vessel's stability, and in the 15th century, the caravel, designed by the Portuguese, based on the Arabic "qarib" which could sail closer to the wind, became more widely used. The towers were gradually replaced by the forecastle and sterncastle, as in the carrack "Santa María" of Christopher Columbus. This increased freeboard allowed another innovation: the freeing port, and the artillery associated with it.