The Making of The Eldridge Conspiracy: Ships in the Middle Ages

Note: All photos in this blog are taken from a video of the cog ship Twekamp af Elbogen arriving at Falsterbo canal in September, 2007. Falsterbo is a town located at the south-western tip of Sweden in Vellinge Municipality in Skåne.04-kaye-nov2016-newsletter

“So might Adam have looked back at Eden; Hornblower remembered the stuffy dark midshipsmen’s berth, the smells and the creakings, the bitter cold nights, turning out in response to the call for all hands, the weevilly bread and the wooden beef, and he yearned for them all, with the sick feeling of hopeless longing. Liberty was vanishing over the horizon. Yet it was not these personal feelings that drove him below in search of action. They may have quickened his wits, but it was a sense of duty which inspired him.”

This is a quote from Mr. Midshipman Hornblower by C.S. Forester, the first book in one of my favorite high seas adventure series. And like young Horatio Hornblower, our young protagonist in the Sir Kaye series, Kaye Balfour, is also motivated by a sense of duty and desire to be like his father.

As a kid, I loved a good swashbuckling high seas adventure, like the Hornblower series, and my Sir Kaye series would not be complete without the addition of an ancient sailing ship. And so, The Eldridge Conspiracy, the fourth and final book in the series, features a cog ship in some of its scenes.

What were cog ships and what role did they play in medieval times?


A cog ship, also simply known as a “cog” was a large, spacious transport ship used in the Middle Ages. The first written history of cog ships dates back to 948 AD in Amsterdam.

When cog ships were first created, they had open hulls (the body of the ship) and could only be rowed short distances. The 13th century saw great advancements in technology for cog ships, which resulted in larger ships with decks, raised platforms, bows, and sterns. Additionally, rudders began to appear on cog ships around 1240 AD. Cog ships gradually replaced the traditional Viking ships in northern Europe. The differences made by these beginning technological advances cannot be overstated: exploration, conquest, and military ventures were each only as successful as the ships that carried their adventurers.

Since there was no photography during the Middle Ages, no one is exactly sure what a cog ship looked like back in its day. Our best guesses come from images of the time, including seals that featured cog ships, and from the best-preserved cog ship, the Bremen cog. However, even on the Bremen cog, only the hull is preserved, and the rig (mast and mast machinery) is gone.


When cog ships were first created, they could only travel very slowly and for short periods of time. But gradually refinements and improvements were made, and by the 13th century, cog ships were strong enough to cross even the most dangerous of oceans, and were equipped to be protected from pirates. Some were even used as warships.

By the 14th century, cog ships had reached their capacity and were slowly phased out by hulk ships.

Features that are common for all cog ships include: One single square sail, clinker outer planking at the sides of the hull, straight steep stem and sternposts (opposed to the rounded Viking stem), relatively flat bottoms, and strong cross-beams, usually protruded through the ships’ sides, holding the sides together.

(For those who care to know: Clinker, also known as lapstrake, is a method of boat building where the edges of hull planks overlap, called a “land” or “landing.”)


The cog ship in The Eldridge Conspiracy is a merchant ship called The Triumph. Compared to older ships modeled after Viking vessels, the cog ship was well-suited for a merchant vessel because of its higher capacity for carrying cargo. The Triumph includes all the design advancements made by the 13th century.

Other than very old and rare cog ship wreckage that has been found, there are no actual cog ships still in existence from the time period. However, there are some recreations.

The Hanseatic Cog at Sea video (about 5 minutes) is of the cog ship Twekamp af Elbogen, a true copy of the cog wreck discovered in Skanör, Sweden in 1991. And all photos in this blog are of the ship in the video.

(If you desire some medieval sailing adventure, cog ship sail tours on the Twekamp af Elbogen are available from Malmo, Sweden during the summer.)


The fourth K4 Making of… blog will give a preview of the fantastic K4 illustrations by Dave Allred, including one of the cog ship The Triumph. And you definitely won’t want to miss the fifth and final K4 Making of… blog where you’ll get to see a pre-release preview of the book.

Don’t miss a thing! Follow the Cardboard Box Adventures blog to join in the fun.

If you’re looking for a series of exciting adventure books that helps reluctant readers, take a peek at the award-winning Sir Kaye series published by Cardboard Box Adventures Publishing.