柯克船或寇格船（Cog），是大航海时代北欧体系船只中最为发达的船舶，在北欧航行至十五世纪左右。一般全长约30公尺，宽约8公尺，总重量约100顿到200顿左右。特征是船体最尾端的舵，一般称其为「船尾中央舵」或「中央舵」。船桅只有一根，位于船体中央，用以张开长方形的横帆，垂直于船首与船尾的连接，适合顺风航行。船体的整体形状是细长形，这是种适合划过北海强风大浪的形状。

柯克船采用「搭接式」造船法制造。搭接式是指四世纪到十五世纪时，用于北欧船只外板的造船法，由数片外板交叠铺成，类似屋顶瓦片的叠法。虽然表面会凹凸不平，但船只构造相当坚固。

A cog (or cog-built vessels) is a type of ship that first appeared in the 10th century, and was widely used from around the 12th century on. Cogs were generally built of oak, which was an abundant timber in the Baltic region of Prussia. This vessel was fitted with a single mast and a square-rigged single sail. These vessels were mostly associated with seagoing trade in medieval Europe, especially the Hanseatic League, particularly in the Baltic Sea region. They ranged from about 15 meters to 25 meters in length (49 ft to 82 ft) with a beam of 5 to 8 meters (16 ft to 26 ft), and the largest cog ships could carry up to about 200 tons.