Germanic tribes occupied northern Europe around 500 AD and developed several new types of ships. The typical merchant ship had a wide hull and deep draft design, and initially carried only one mast, which was increased as the ship grew larger. The ancient Scandinavians called this type of ship the Norse. We know more about this type of ship today because the remains of one of the same type were found at the bottom of a harbor in Denmark in the 1960s. Many Anglo-Saxons and Vikings used this type of ship for trade and exploration. The Noel was later developed into a merchant ship and was the most important trading merchant ship of the late Middle Ages. This deep draft line was designed to be easier to navigate and increase cargo capacity.
Ship battles, which took place in northern Europe, were largely an extension of the land battle format. Merchant ships were protected by archery towers at the bow and stern, and had platforms that allowed bowmen to fire. Although the crews of both sides would use their bows and arrows to attack each other as the ships approached each other, the effect was simply to kill or injure the enemy's crew and soldiers. Ships could join forces with each other to engage enemy ships in physical combat, although ships navigating these waters were not capable of ramming. Until the advent of artillery in the fourteenth century, there were no weapons that could cause great structural damage to an enemy ship or sink it, and the Battle of Slolisie in 1340, in which some four hundred English and French merchant-type ships with large numbers of bowmen and foot soldiers took part, can be considered a typical naval battle of the late Middle Ages. These troops were attached to each other and worked in concert for bow and arrow shooting and close combat.
The first guns were mounted on the bow and stern of the ship, with smaller guns mounted on the side to attack the enemy's crew. The English ship HMS Christofta, built in 1406, was the first ship specifically designed to mount guns. It wasn't until near the end of the Middle Ages that ships began mounting side guns to break the hulls of enemy ships.
The great Viking warships were used more for transportation than combat. In fact the Vikings rarely fought from their warships. When they did intend to fight, they would tie their ships together as platforms for physical combat. Before the use of sails began in the eighth and ninth centuries, the great Viking warships were powered by oars. Although these ships may seem fragile and unlike the ships used for sailing, modern replicas prove that they were in fact very seaworthy. The much greater range achieved by the use of sails explains how the Vikings were able to launch their invasions in the ninth century.
The Irish coracle was a small boat used mainly for coastal trade and navigation, but also for deep-sea voyages. They were made of animal hides wrapped around a wooden frame. The leather on the boat is sealed with bitumen to waterproof it. These extremely lightweight boats were propelled by small sails or oars. In bad weather, the leather shells would be closer together to keep the boat's water level tight and less likely to sink. Before the Vikings, Irish monks used these boats to explore the North Atlantic and reach Iceland.
The Crusaders brought northern European ships to the Mediterranean, bringing sailors and shipbuilders from north and south into contact. Southerners began to adopt some of the features of the northern merchant marine, including its large hull and square sails. The northerners, in turn, learned about the manufacture of compasses, stern rudders, and large spinnakers.