Mad about science: The challenges of viking ships

By Brenden Bobby
Reader Columnist

The Vikings were tough. Masters of the sea, conquerors of entire nations, and feared for their brutality and ruthlessness in combat. They were masters of their age in every respect; and, to accomplish all that they achieved over the course of three centuries, they had to utilize every resource at their disposal.

The North Atlantic is one of the most inhospitable environments in the world. There was very little food, no potable water and no warmth without the risk of turning a longboat into a funeral pyre. How did the Vikings not only survive, but thrive in some of the worst conditions on the planet?

Cold was the great killer of the sea. Modern shipping and fishing is far from luxurious, but modern vessels come with many comforts the Vikings critically lacked. Electric and gas heating are chief among these modern luxuries that would have been unthinkable during the Viking Age. Temperatures in the North Atlantic during this era hovered around freezing. Zero degrees Celsius is uncomfortable, but once mixed with water can very rapidly become lethal. Wind and water together pull heat from the human body extremely quickly.

Our sweat works by cooling the body through evaporation and through conduction. Water is a great conductor of heat, absorbing heat and releasing it through the air when the wind blows. In warmer conditions, the energy required to convert sweat into vapor releases the heat energy trapped by the sweat droplets. On the frigid North Atlantic, the water from the sea and sky are too cold to evaporate; so, instead, the wind pulls the heat straight from the water and disperses it into surrounding water as well as the air.

Combating this in a historical period before electric and gas heat was extremely tricky, but not impossible.

The Vikings had an intimate understanding of the principles of conduction. Many had spent generations on the sea and had learned exactly how heat transfer worked. They solved this not by simply layering on clothing, but by building and selecting specific types of apparel for specific weather conditions. They would even mend their clothing daily to keep in the heat.

Vikings also looked to nature for protection. Animals that call Europe’s northern coasts home had everything the Vikings needed to survive the sea. Sheep’s wool coated in beeswax or oil helped wick water away and keep precious heat trapped inside garments. Thick animal furs laid over natural fibers helped further insulate the sailors — reindeer hides in particular were a Viking favorite. 

Reindeer have two layers of fur with a thick layer to trap in body heat and a second guard hair layer that insulates by holding in a layer of air. Seal hides were another source of warmth for Viking sailors, particularly during rough seas or storms when water spray threatened to soak the voyagers to the bone.

Women aboard Viking vessels would aid in mending crews’ clothing daily with thick cord and bone needles. They would sew together layers to create an airtight seal at the wrist, then cover them with gloves to prevent air leaking from the sleeves. Should the threat of battle loom, the sailors would cut the cord to open their sleeves and maximize their mobility. You can see this layering happen in modern ski gear and winter wear, where people will seal the clothing gap from their wrists with gloves.

Little to no heat on a Viking vessel was generated by fire. Fire was a liability on ships as the entire structure was made of wood and stuffed with flammable pitch and animal furs. Even the mast was coated in highly flammable animal fats to keep it waterproof. Instead, the bulk of heat was generated by the Vikings themselves.

Clothing was imperative for survival, but even more important were the two-person sleeping bags made of sheepskin and animal hides that Vikings utilized on sea voyages. These waterproof and nearly airtight bags were a cozy and intimate experience, allowing for communal sleeping that kept sailors up to 20 degrees Fahrenheit warmer than if they were sleeping alone. Being mostly airtight, their faces were exposed to the elements, but also kept safe from unimaginable body odor and the natural digestive results of a North Sea-based diet.

Despite being oceanworthy, Viking vessels weren’t particularly well suited for very long ocean voyages. They were meant to stick close to shores so that the ship’s cook could collect and boil water and serve food up to twice a day. Of course, for longer treks, Vikings could stockpile some food and water, but these open vessels were hardly suited to the weeks or monthslong voyages that massive galleons could commit to during the Age of Sail centuries later.

The open design of Viking ships compared to more enclosed galleons and ships-of-the-line that came later was interesting, as it gave them tremendous visibility and the capability to rapidly board other craft while stockpiling their own materials. However, they were extremely prone to fire, more so even than multi-decked warships of later centuries. Air is fuel for fire, and the more air available to a flame, the faster it will burn. A warship with multiple decks and bulkheads can effectively snuff out a fire with its own smoke, while an open longship could go from freezing to flaming in as little as four minutes.

It’s safe to say that Vikings didn’t roast a lot of s’mores while out at sea.

Stay curious, 7B.