1. Cogs developed from the ancient Celtic flat bottomed boat and did not have a keel. The earliest mention of a Cog is 948 AD near Amsterdam. High sided and heavy the Cog was an ideal cargo vessel. The stern rudder replaced the steering oar in the early 13th century. Add a 'castle' to the stern and/or bow and the Cog become a naval vessel ready for battle. Soldiers and marines used bows, arrows and catapults - later guns also - to soften up the crew on an enemy ship by firing from the cog's 'castle' before boarding.

3. Hulks had upturned stakes which terminated above the waterline. A keel carved from a great log was upturned at both stern and bow. The earliest known Hulk dates from the late 8th century at Utrecht.

4. Carracks were developed in the Mediterranean in the 15th century and had three or four masts and therefore the potential to be larger than any Cog or Hulk. They can be considered a fusion of the Cog, Hulk and Knarr, and a larger and more capable vessel was thereby created. Carracks had high rounded sterns with an aftcastel. Forecastles and bowsprits were also builton many Carracks. Carrack's were square rigged on the foremast, lateen rigged on the mizzenmast. They could handle rough seas, albeit rolling and pitching, and were therefore Europe's first long distance, ocean voyaging ship. The Spanish and Portuguese explored the world in Carracks in the 15th and 16th centuries. Columbus's flagship the Santa Maria was a small Carrack. Henry VIII's famous Mary Rose was a large Carrack built to exacting standards as a naval war ship.